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The development of prosodic contrastivity during the first year of life Fowlow, Patricia J. 1975

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THE DEVELOPMENT OF PROSODIC CONTRASTIVITY DURING THE FIRST YEAR OF LIFE by P a t r i c i a J. Fowlow B.Sc, University of Calgary, 1972 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the Department of Paediatrics D i v i s i o n of Audiology and Speech Sciences We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA July, 1975 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l m a k e i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e H e a d o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 Wesbrook Place Vancouver, Canada V6T 1W5 D a t e .-r?*c^€. =5, /9~A£ ABSTRACT The r e l a t i o n s h i p between the infant's e a r l y vocal develop-ment and subsequent speech and language development has been generally a matter of speculation, l a r g e l y based upon anecdotal evidence, despite the voluminous l i t e r a t u r e on the subject. In-cluded i n the e x i s t i n g data on infant prosodic development are ' descriptions of d i f f e r e n t i a t e d crying behaviour ostensibly ex-pressive of d i f f e r e n t i n t e r n a l states such as pain, hunger and pleasure. Instances of d i f f e r e n t i a l v o c a l i z a t i o n to objects and people have likewise been alluded to i n the l i t e r a t u r e , but no systematic studies of the phenomenon have been made. The present study examines c e r t a i n aspects of vocal d i f f e r -e n t i a t i o n and d i f f e r e n t i a l v o c a l i z a t i o n , p r i m a r i l y with respect to f a m i l i a r environmental objects. Nineteen normal, healthy, ' f i r s t - b o r n ' infants served as subjects. A l l were being raised i n an exc l u s i v e l y monolingual English home environment, where a l l data were c o l l e c t e d at biweekly i n t e r v a l s from f i v e weeks to approximately one year of age. The vo c a l i z a t i o n s of ten of the infants were studied l o n g i t u d i n a l l y over an en t i r e year, the remaining subjects from f i v e weeks to approximately six months. Intonation patterns of non-cry v o c a l i z a t i o n s occurring i n two basic s i t u a t i o n s ( i . e . , infant alone and inf a n t i n the con-text of various objects) were analyzed spectrographically for fundamental frequency, within-utterance range, duration and c o n t o u r . E a c h v a r i a b l e was e x a m i n e d l o n g i t u d i n a l l y a n d i n d i f f e r e n t c o n t e x t s . A number o f age t r e n d s a r e e v i d e n t : D u r a t i o n a n d w i t h i n -u t t e r a n c e r a n g e i n c r e a s e w i t h a g e , w h e r e a s f u n d a m e n t a l f r e q u e n c y r e m a i n s r e l a t i v e l y s t a b l e o v e r t h e f i r s t y e a r . F e m a l e s e x h i b i t a h i g h e r F Q t h a n m a l e s a t a l l age l e v e l s e x a m i n e d . P e a k v a l u e s o f t h e v a r i a b l e s a r e commonly o b s e r v e d a t 4 - 6 , 9 a n d ( t o a l e s s e r d e g r e e ) 1 1 m o n t h s . The RF i n t o n a t i o n c o n t o u r i n c r e a s e s i n f r e q u e n c y o f o c c u r r e n c e d u r i n g t h e f i r s t y e a r , w h i l e t h e o t h e r c o n t o u r s d e m o n s t r a t e l i t t l e c h a n g e . C o n t r a s t s o f u t t e r a n c e s o c c u r r i n g i n d i f f e r e n t c a t e g o r i e s r e v e a l e s s e n t i a l l y no d i f f e r e n c e b e t w e e n c o n t e x t s f o r t h e v a r -i a b l e s s t u d i e d . E x a m i n a t i o n o f t h e d i s t r i b u t i o n s o f t h e d i f -f e r e n t i n t o n a t i o n c o n t o u r s f o r e a c h c o n t e x t i n d i c a t e s t h a t t h e i n f a n t s c o u l d be m a n i p u l a t i n g c o n t o u r d i f f e r e n t i a l l y i n a g i v e n c o n t e x t . I n sum, i t i s f e l t t h a t t h e i n f a n t s e x h i b i t a v e r y r e a l , a l b e i t c i r c u m s c r i b e d , c a p a c i t y f o r v o c a l l y d i f f e r e n t i a t i n g e n -v i r o n m e n t a l e v e n t s . I t i s f e l t t h a t t h e r e e x i s t s s u f f i c i e n t e v i d e n c e t o r e f u t e t h e p a r o c h i a l v i e w t h a t l i n g u i s t i c a c q u i s i t i o n c a n o n l y be r e l e v a n t l y d i s c u s s e d when t h e c h i l d ' s s e g m e n t a l p h o n e t i c o u t p u t b e g i n s t o r e s e m b l e t h a t o f t h e a d u l t s t a n d a r d . The e v i d e n c e p r e s e n t e d c o r r o b o r a t e s t h e h y p o t h e s i s o f c o n t i n u i t y f r o m b a b b l i n g t o s p e e c h . TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS i v LIST OF TABLES ix LIST OF FIGURES x ACKNOWLEDGMENTS x i i Chapter 1: INTRODUCTION > 1 1.1 Introduction 1 1.2 L i t e r a t u r e Review 8 1.21. Receptive capacity of the infant 8 1.22. Productive capacity: The in f a n t larynx 18 1.23. Cognitive development and im i t a t i o n i n the Sensorimotor Period 21 1.24. B i o l o g i c a l l y based theories of infant v o c a l i z a t i o n 26 1.25. Methods used i n the study of infant v o c a l i z a t i o n s 29 1.26. Studies of infant vocal output 32 1.261. Acoustic studies 32 1.262. Intonation studies 39 1.27. Extralingui,stic factors i n language de-velopment 47 1.271. Conditioning studies 47 1.272. Parent-infant studies 51 1.3 Summary and statement of the problem 58 i v V Page Chapter 2: METHOD 61 2.1 Experimental design 61 2.2 Subjects 64 2.21. Sex and age range 64 2.22. Medical h i s t o r y 65 2.23. Home environment and biographical i n f o r -mation on the families 65 2.231. Language, education, occupation and income 65 2.232. Heimler Scale r e s u l t s 66 2.233. Household organization 70 2.234. Maternal care 71 2.3 Procedure 7 4 2.31. Data c o l l e c t i o n 74 2.311. Instrumentation 74 2.312. Taping s i t u a t i o n 74 2.32. Spectrographic analysis 75 2.321. Instrumentation 75 2.322. Selection and c l a s s i f i c a t i o n of utterances 76 2.323. R e l i a b i l i t y of context for the objects 77 2.324. Production of spectrograms .... 77 2.33. Measurement of spectrograms 78 2.331. Measurement of fundamental f r e -quency 78 v i Page 2.332. C a l c u l a t i o n of within-utterance range 79 2.333. Measurement of duration 79 2.34. S p e c i f i c a t i o n of the objects and object categories 79 2.35. C l a s s i f i c a t i o n of the contours 80 2.36. Hotelling's T 2 tests .'. . . 81 2.37. Multiple C l a s s i f i c a t i o n Analysis 82 2.38. Multiv a r i a t e Nominal Scale Analysis .... 87 2.39. Development of the intonation contours with age 88 Chapter 3: RESULTS 89 3.0 Introduction 89 3.1 Hotelling's T 2 contrasts 89 3.11. Contrasts of utterances with a single middle-point 90 3.12. Contrasts of utterances with two middle-points 90 3.13. Contrasts involving the same intonation contours 92 3.131. Intonation contours having one measured middle-point 92 3.132. Intonation contours having two measured middle-points 92 3.14. One middle-point vs two middle-point contrasts 96 3.15. Contrasts of d i f f e r e n t intonation contours 97 v i i Page 3.16. Examination of cases having small sam-ple sizes 98 3.2 Comparison of the age metrics: Chronological Age, Bayley Mental score and Bayley Motor Score 98 3.3 Results of Multiple C l a s s i f i c a t i o n Analysis .. 102 3.31. Age and sex trends of the dependent var-ia b l e s and two re l a t e d indices 102 3.32. The use of CONTEXT as a predictor 109 3.33. Intersubject v a r i a b i l i t y 112 3.4 Intonation contour configurations 113 3.5 Results of M u l t i v a r i a t e Nominal Scale Analysis 114 3.51. Intonation contour d i s t r i b u t i o n s ...... 114 3.511. D i s t r i b u t i o n of contour by age 114 3.512. D i s t r i b u t i o n of contour by sub-j e c t and by sex 116 3.52. Context d i s t r i b u t i o n s 118 3.521. D i s t r i b u t i o n of context by age 118 3.522. D i s t r i b u t i o n of context by sex 123 3.53. D i s t r i b u t i o n of contour by context .... 124 Chapter 4: DISCUSSION 127 4.1 Review of the present r e s u l t s i n r e l a t i o n to theory and previous research 127 4.2 Limitations of the present i n v e s t i g a t i o n 135 4.21. Sample size 135 4.22. C l a s s i f i c a t i o n of utterances according to context 135 4.23. Measurement 136 v i i i P a g e 4.3 I m p l i c a t i o n s f o r t h e o r y a n d f u t u r e r e s e a r c h .. 137 4.4 Summary 138 BIBLIOGRAPHY 140 APPENDIX A 151 APPENDIX B: A v e r a g e d d a t a f o r M u l t i p l e C l a s s i f i c a -t i o n A n a l y s i s 155 APPENDIX C: D i s t r i b u t i o n a l d a t a d e r i v e d f r o m M u l t i -v a r i a t e N o m i n a l S c a l e A n a l y s i s 162 APPENDIX D: M i s c e l l a n e o u s d a t a 168 i LIST OF TABLES Table Page I A Summary of the C h a r a c t e r i s t i c s of Infant Cries 4 II Infant Intonation Patterns and Their Adult Counterparts 44 III Percent Occurrence of Each Intonation Contour for B i r t h , Pain/ Hunger and Pleasure Signals ... 46 IV , Parental Biographical Information 67 V Mothers' Preferred Modes of Stimulation 73 VI S i g n i f i c a n t Contrasts for Utterances Having the Same Number of Middle-points 91 VII Contrasts Involving the Same Intonation Contours 93 ix LIST OF FIGURES Figure Page 1 Maximum possible contrasts occurring when u t t e r -ances are examined according to number of middle-points 83 2 Contour contrasts 84 3 A l l subjects (N=19): Means of F , duration, and within-utterance range with respect to chrono-l o g i c a l age and the mental and motor scores based on the Bayley Scales of Infant Development 100 4 A l l subjects (N=19): Means of F , duration and within-utterance range (11,368 vocalizations) 103 5 Females (N=7): Means of F , duration, and within-utterance range (4,540 vocalizations) ... 104 6 Males (N=12): Means of F , duration, and within-utterance range (6,828 vocalizations) ... 105 7 A l l subjects (N=19): Means of Range to Duration and.of mean F Q x Duration x Range 108 8 Contours and t h e i r development status i n three age categories for a l l subjects 115 9 Developmental trend of frequency of each contour for a l l subjects T.17 10 Percentage d i s t r i b u t i o n of contour frequency for each subject and for a l l subjects 119 11 Percentage d i s t r i b u t i o n of v o c a l i z a t i o n s by con-tour and context for females and males 120 x x i Figure Page 12 Developmental trend of frequency of each context fo r a l l subjects 122 13 Percentage d i s t r i b u t i o n of contours by context for a l l subjects 125 ACKNOWLEDGEMENTS To a l l those who gave so generously of t h e i r time i n helping to make t h i s thesis a r e a l i t y , I should l i k e to express my sincere gratitude. My thanks go e s p e c i a l l y to: Dr. John Delack for his supervision and advice, and for his c a r e f u l revisions of the many d r a f t s ; John G i l b e r t for acting as a committee member; Judy Davis for her part i n the i n i t i a l c o l l e c t i o n of the data, and for the biographical information on the infants and t h e i r f a m i l i e s ; Dale Stevenson and John N i c o l for computer programming and for leading me through the maze of mathematical equations; also to Dale Stevenson for his excellent graphic i l l u s t r a t i o n ; Barbara Purves for spectrographic analysis and standard-i z a t i o n of the data; the many others who have been involved i n the project since i t s inception; my classmates Sharon, Ingrid, Betty, Meralin and Lyn for th e i r comradeship; and my family for t h e i r support and encour-agement. The research reported herein was supported i n part by the Department of National Health and Welfare (Canada), under Federal Public Health Project No. 609-7-324 and Medical Research Council Grant No. MA-5369 (Pri n c i p a l Investigator: Dr. John B. Delack). CHAPTER 1 Introduction 1.1. Introduction '...the wants of an infant are at f i r s t made i n t e l l i g i b l e by i n s t i n c t i v e c r i e s , which a f t e r a time are modified i n part unconsciously, and i n part, as I believe, v o l u n t a r i l y as a means of communication, — by the unconscious expression of the features, — by gestures and i n a marked manner by d i f f e r e n t intonations, — l a s t l y by words of a general nature i n -vented by himself, then of a more precise nature imitated from those which he hears; and these l a t t e r are acquired at a wonderfully quick rate.' (Darwin, 1877, p. 8) I t i s generally agreed that the infant's cry i s a p r i m i t i v e mode of expression. Many people have offered hypotheses re-garding the r o l e of early cry and non-cry utterances i n the continuum of language development, but r e l a t i v e l y few have studied the subject systematically. Those who have undertaken studies of i n f a n t v o c a l i z a t i o n during the f i r s t year of l i f e have been faced with ostensibly insurmountable problems i n data c o l l e c t i o n , analysis, and i n t e r p r e t a t i o n of r e s u l t s . The researcher i s further confronted by a multitude of uncontrollable variables, such as genetic make-up, rate of development, and environmental factors. A l l of these variables must ultimately 1 2 be taken into account i n any theory of language development which claims to be comprehensive. Early investigators i n language a c q u i s i t i o n acknowledged that the i n f a n t cry acquired an expressive function very soon a f t e r b i r t h (Lewis, 1951). The newborn was thought to o s c i l l a t e between two st a t e s : discomfort and i n d i f f e r e n c e : Discomfort was denoted by the cry, i n d i f f e r e n c e by s i l e n c e . Later, a com-f o r t cry would emerge. Comfort and discomfort were d i f f e r e n t i a l l y expressed', while the state of i n d i f f e r e n c e continued to be i n -dicated by s i l e n c e . As the infant grew older, the state of hunger also became d i f f e r e n t i a t e d v o c a l l y . Today, t h i s idea of progressive d i f f e r e n t i a t i o n of the cry i s widely accepted. Not only i s i t compatible with a maturational approach to language a c q u i s i t i o n , but i t can be explained by c e r t a i n learning theory approaches as w e l l . • Wasz-Htickert et a l . (1968) demonstrated that c r i e s a r i s i n g i n d i f f e r e n t s i t u a t i o n s ( v i z . , b i r t h , pain, hunger and pleasure) exhibited d i f f e r e n t acoustic c h a r a c t e r i s t i c s ; c f . Table I. Wolff (1969) discussed t h i s phenomenon of d i f f e r e n t i a l crying at length. In the Wasz-Httckert study, adults who had varying de-grees of experience i n caring for young babies, were asked to judge the d i f f e r e n t types of cry i n a perceptual t e s t . The sub-j e c t s were able to i d e n t i f y d i f f e r e n t cry types, but i t was found that the amount of experience with young babies influenced the number of correct judgments: midwives, children's nurses, and mothers were best able to i d e n t i f y the d i f f e r e n t cry types; 3 pleasure c r i e s were most e a s i l y i d e n t i f i e d , followed by hunger, pain and b i r t h c r i e s i n that order. Insert Table I about here. In contradiction to Wasz-Hockert et a l . , a recent study of cry i d e n t i f i c a t i o n a b i l i t i e s of mothers (Mtiller et a l . , 1974) found that mothers were usually unable to i d e n t i f y the s i t u a t i o n of the cry. Three types of cry-evoking s i t u a t i o n s were examined: pain stimulation ( e l a s t i c band snapped against c h i l d ' s f o o t ) , auditory stimulation (loud clap of wooden blocks) and hunger stimulation (feeding was begun and then suddenly halted). With the exception of the pain stimulation, these cry s i t u a t i o n s are not comparable to those employed by Wasz-Hflckert et a l . The cry produced i n response to auditory stimulation might be described as a form of s t a r t l e response, as might the pain cry. The Wasz-Hockert 'hunger c r y 1 was produced about four hours a f t e r the infant's l a s t feeding; a l l other reasons for discomfort were discounted. The Mtiller 'hunger cry', on the other hand, was e l i c i t e d a f t e r feeding had begun; t h i s cry could thus be i n t e r -preted as a cry of f r u s t r a t i o n or anger rather than hunger. The authors recognized t h i s p o s s i b i l i t y but argued that the term 'hunger stimulation' was operationally defined for the purposes of t h e i r research and that the cry was hunger-related (Mtiller et a l . , p. 92). The four cry categories of Wasz-Hockert et a l . TABLE I A SUMMARY OF THE CHARACTERISTICS OF INFANT CRIES -^Type Features^-^. BIRTH PAIN HUNGER PLEASURE Length approx. 1 sec long; v a r i a t i o n i n length; longer with increase i n age approx. 1 sec approx. 1 sec Melody Level or F a l l i n g F a l l i n g ; Rising-f a l l i n g i s rare more than two-thirds are Rising-f a l l i n g Level - often nasal Tense always usually approximately one-half are tense never G l o t t a l Plosives rare 0-1 mo. - present i n 50% the c r i e s ; decrease with age present; a f t e r 1 mo. occur i n two-thirds of cries rare Vocal Fry rare i n more than half of the c r i e s rare rare Subharmonic Break rare i n about 50% of c r i e s ; increase with age rare occurs i n about o n e - f i f t h of the signals S h i f t present i n approx. 20% of signals often present (30-40%) rare occurs, usually i n R i s e - f a l l Voice 60% voiceless 0- 1 mo. - 65% voiced 1- 7 mo. - 72% voiced 0- 1 mo. - 60% voiced 1- 7 mo. - 68% voiced always Maximum Pit c h 550 ± 70 Hz high; increases with age few marked changes with age more variable p i t c h (based on Wasz-Httckert et a l . , 1968) 5 encompass a wide var i e t y of s i t u a t i o n s . Mtiller's categories could be described as subsets of one major category, namely 'pain 1. I t i s possible that c r i e s within t h i s major category may not be a c o u s t i c a l l y d i f f e r e n t even though t h e i r evoking s t i m u l i may be d i f f e r e n t (e.g. loud noises, br i g h t l i g h t s , pinches, f r u s t r a t i o n ) . Muller et a l . did not include any spectrograms with t h e i r r e s u l t s , and consequently i t i s d i f f i c u l t to judge whether the three types of c r i e s were a c t u a l l y acous-t i c a l l y d i f f e r e n t . Thus f a r we have discussed the infant's a b i l i t y to si g n a l • major i n t e r n a l states by d i f f e r e n t types of utterances. I t appears that changes i n the c h i l d ' s external environment can also be s i g n a l l e d by a change i n the c h i l d ' s vocal output. The vocal behaviour that occurs i n these s i t u a t i o n s has been variously l a b e l l e d 'imitation', 'role-playing', and 'response to a novel s i t u a t i o n ' . Lieberman (1967) c i t e d evidence based on two c h i l d r e n , a 10-month-old boy and a 13-month-old g i r l , both of whom alte r e d t h e i r fundamental frequency i n the presence of a parent. A lower fundamental frequency was used i n the presence of the father than i n the presence of the mother. The boy used a higher fundamental frequency when playing alone than he did when playing with eith e r his father or h i s mother. Unfortu-nately, Lieberman gives no information as to how he obtained the data or how many observations were made, nor does he specify the nature of the adult stimulus i n more than anecdotal fashion. A f t e r studying the babbling of his twin daughters, Cruttenden (1970) was unconvinced that 'meaningful or indeed 6 "delimitative" p i t c h patterns' occurred during the babbling stage (p. 112). Some patterns were imitated and put into use. Both twins experimented with p i t c h r e g i s t e r . One co-twin employed two p i t c h r e g i s t e r s , one very high and the other low and creaky. The author did not note whether these two r e g i s t e r s were being employed i n d i f f e r e n t s i t u a t i o n s . C r y s t a l (1973b) r e f e r s to a c h i l d who employed a f a l s e t t o voice when playing with his rabbit, and a chest voice when playing with his panda; both of 'these were ostensibly toy animals. He suggests that t h i s type of behaviour could be con-strued as role- p l a y i n g . Recently, a study of vo c a l i z a t i o n s i n infants from f i v e weeks to four months of age, was c a r r i e d out (Handford, 1972) i n which i t was found that the ch i l d r e n generally did not a l t e r t h e i r fundamental frequency or within-utterance range (of fundamental frequency) i n response to d i f f e r e n t objects or si t u a t i o n s . However, twenty percent of the s t a t i s t i c a l tests c a r r i e d out were s i g n i f i c a n t , demonstrating that the childre n were at l e a s t capable of a l t e r i n g t h e i r vocal output i n d i f f e r e n t s i t u a t i o n s . The intent of the present study i s to examine, i n ac o u s t i c a l terms, the intonation patterns of non-cry v o c a l i z a t i o n s of the infant i n two basic s i t u a t i o n s : (1) inf a n t alone, and (2) infant ' i n the context of various objects. Ten subjects were studied l o n g i t u d i n a l l y from f i v e weeks to one year of age. An ad d i t i o n a l eight subjects were studied from f i v e weeks to s i x months of age. 7 The r e s u l t s are examined and discussed, keeping i n mind the c h i l d ' s developing physical and cognitive c a p a c i t i e s . 8 1.2. L i t e r a t u r e Review 1.21. Receptive capacity of the infant In any study of an in d i v i d u a l ' s speech and language develop-ment, one i s f i r s t concerned with that person's receptive c a p a b i l i t i e s . How then might the infant be equipped to receive and process the speech signal? What kinds of perceptual tasks can the infant perform? Although we are far from being able to answer these questions, some data are a v a i l a b l e . During the f i r s t two years of l i f e , about s i x t y percent of brain development occurs (Lenneberg, 1967, p. 179). St r u c t u r a l , chemical and e l e c t r o p h y s i o l o g i c a l changes take place at a rapid rate, during which time the in f a n t develops an ever-expanding repertoire of gross and fin e motor s k i l l s . P a r a l l e l i n g t h i s p h y s i c a l growth i s the rapid growth of receptive and expressive language, as well as other cognitive s k i l l s . Myelin, a substance which envelops the axons of many nerve c e l l s i n the body, aids i n accelerating the transmission of nerve impulses. Myelination, the process by which nerve c e l l s acquire a myelin sheath, i s incomplete at b i r t h . In the brain, myelination occurs i n an ordered sequence, and i n the d i r e c t i o n of the pathway concerned. The medulla i s myelinated f i r s t , followed by the basal ganglia, mesencephalon and f i n a l l y the cortex (Peiper, 1963, pp. 539-541; Yakovlev and Lecours, 1967; Lecours, 1972ms). The auditory nerve i s f u l l y myelinated at b i r t h ; however, myelination of the two c l a s s i c a l speech and language areas of the brain, Broca's area and Wernicke's area, 9 takes place more slowly over the f i r s t two years of l i f e . Thus, given the status of the auditory t r a c t , the i n f a n t could r a p i d l y become a sophisticated l i s t e n e r , whereas overt speech and language s k i l l s would emerge more slowly. The asymmetry of the l e f t and r i g h t hemispheres, which i s evident i n most adults and generally indicates hemispheric dominance f o r speech and language, i s demonstrable i n fetuses as early as twenty weeks gestational age (Wada, 1974) . A study by Molfese (1973) indicates that the brain processes speech and music d i f f e r e n t i a l l y at b i r t h : auditory evoked responses to speech, s y l l a b l e s , words, music and speech noise were recorded from the temporoparietal areas i n both the r i g h t and l e f t hemi-spheres i n inf a n t s , c h i l d r e n and adults. In a l l subjects, verbal s t i m u l i e l i c i t e d the greatest amount of AER a c t i v i t y from the l e f t hemisphere, while non-verbal s t i m u l i e l i c i t e d more a c t i v i t y from the r i g h t hemisphere. The structures of the ear are f u l l y developed at b i r t h . T r a d i t i o n a l l y , i t was believed that the middle ear was f i l l e d with mucous at b i r t h . The resultant conductive loss would then i n t e r f e r e with the infant's response to sound. Tympanometry and measurements of the compliance of the tympanic membrane have revealed that neonates have normal middle ear function and that mucous i s not present (Keith, 1974). The few W-shaped tympano-grams (usually i n d i c a t i n g hypermobility of the eardrum but not observed with a 220-Hz probe tone) that were observed were thought to be i n d i c a t i v e of unresolved embryonic connective 10 t i s s u e pressing against a part of the eardrum. Wertheimer (1961) demonstrated auditory l o c a l i z a t i o n i n an inf a n t less than ten minutes o l d . Eisenberg et a l . (1964) reported that neonates were d i f f e r e n t i a l l y responsive to signals within the speech range (250-4000 Hz). Signals below 4000 Hz e l i c i t e d responses two to three times more often than signals above 4000 Hz. High frequency signals tended to cause d i s t r e s s , whereas low frequency signals tended to i n h i b i t i t . Low frequency stimulation evoked gross motor responses when the inf a n t was dozing. High frequency stimulation e l i c i t e d the high-est proportion of arousal and o r i e n t i n g quiet reflexes' and was most e f f e c t i v e when the infants were i n wakeful states. Kearsley (1973) reports that newborns are d i f f e r e n t i a l l y responsive to auditory stimulation. Further, they are capable of integrated o r i e n t i n g and defensive behaviour. The onset of the auditory event i s apparently the most important factor i n determining a response. As with Eisenberg et a l . , the studies of both Kearsley (1973) and Pomerleau-Malcuit and C l i f t o n (1973). recognize the importance of the state of the organism i n i t s response to a stimulus. Pomerleau-Malcuit and C l i f t o n (1973) found less v a r i a b i l i t y i n neonatal response to t a c t i l e , auditory and v e s t i b u l a r stimulation before the infant was fed. , Friedlander (1968) has attempted to examine the l i s t e n i n g preferences of young infants, using an automated behaviour analysis toy which can be attached to a standard playpen. The 11 toy allows the childre n to s e l e c t between p a i r s of auditory s t i m u l i which have been recorded on tape loops. A study of three i n f a n t boys, aged eleven to t h i r t e e n months, demonstrated a preference f o r the mother's voice over music. When presented with a choice of l i s t e n i n g to the mother's monotone voice or a stranger's voice with bright i n f l e c t i o n , the youngest subject showed a preference for the stranger's voice, whereas the 15-month-old subject showed a s h i f t from preference of the stran-ger's voice with bright i n f l e c t i o n to the mother's voice with f l a t i n f l e c t i o n . The t h i r d subject (12-months-old) was given the task of discriminating a sample of his mother's speech i n which she employed f a m i l i a r phrases and a bright i n f l e c t i o n , and a sample of the mother reading i n a f l a t , monotonous voice. At f i r s t , the c h i l d showed a preference for the mother's bright voice, but t h i s was followed by a s h i f t i n preference f o r the monotone version of the mother's voice. This same subject was given a further task involving s e l e c t i o n of speech samples which d i f f e r e d i n message redundancy. The low redundancy message repeated i t s e l f every 240 seconds, while the high redundancy message was a 20-second sample edited from the longer message. During the i n i t i a l sessions, the in f a n t showed a preference for the repeating 20-second message. F i n a l l y , there was a switch to preference f o r the longer message. These r e s u l t s were subse-quently duplicated using 40-second and 120-second repeating messages. In a l a t e r study employing more subjects (Wisdom and Friedlander, 1971), almost one-half of the infants preferred the low-redundancy, high-inforamtion message. Six of the subjects 12 showed a d i s t i n c t s h i f t i n preference from low-information, high redundancy to high-information, low-redundancy. There are p a r a l l e l s between F r i e d l a n d e r 1 s observations of s h i f t i n g preference from the f a m i l i a r to the novel, and observations on i n f a n t v i s u a l behaviour (recorded at a somewhat e a r l i e r age). Infants f i x a t e on complex v i s u a l patterns more than simple patterns, and on complete faces rather than scrambled ones. Wetherford and Cohen (1973) obtained response habituation to a f a m i l i a r pattern at ten to twelve weeks but not at six to eight weeks. The older subjects preferred novel patterns, while the younger ones preferred f a m i l i a r patterns. Evidence to supplement the observations regarding i n f a n t l i s t e n i n g preferences e x i s t s i n the realm of speech perception. At two weeks, infants are capable of discriminating vocal and non-vocal s t i m u l i (Wolff, 1969) . Between two and four months, discrimination of the a f f e c t i v e q u a l i t i e s of voices occurs (Lewis, 1951; Lieberman, 1967; Wolff, 1969). Familiar and unfamiliar voices are also distinguished at t h i s age (Kaplan and Kaplan, 1971). Turnure's (1971) three-month-old subjects exhibited more mouth movements during the presentation of the mother's voice than during the presentation of a stranger's voice. Kaplan (1970) mentioned that, i n preliminary t e s t i n g , four-month-old infants were able to discriminate between a male and a female voice repeating the same utterance: "See the cat." V a r i a b i l i t y i n both heart rate and o r i e n t i n g responses increased when the voice 'changed from male to female, and v i c e versa'(p. 10). 13 Kaplan and Kaplan (1971) suggest that the young in f a n t (under seven months of age) i s more attuned to the suprasegmental components of speech. A f t e r s i x months he/she i s supposedly more aware of segmental information. Several studies have been devoted to the young infant's perception of segmental information. The high amplitude sucking paradigm (HASP) has been used as the response measure i n the majority of these studies. Eimas et al.(1971) found that one- to four-month-old infants were able to discriminate synthesized versions of /b/ and /p/; these sounds had the acoustic properties associated with the s y l l a b l e s /ba/ and /pa/. The r e s u l t s indicated a tendency towards c a t e g o r i c a l perception, i . e . d i s c r i m i n a t i o n across phoneme boundaries rather than within phoneme categories. M o f f i t t (1971) demonstrated d i s c r i m i n a t i o n of /ba/ and /ga/ i n infants from twenty- to twenty-four-weeks of age. Trehub and Rabinovitch (1972) found that infants could discriminate between the synthetic speech s t i m u l i /ba/ and /pa/, as well as the natural speech s t i m u l i /ba/ vs /pa/ and /da/ vs / t a / . The sub-jects i n t h e i r study were between four- and seventeen-weeks old. Morse (1972) tested the a b i l i t y of 40- to 54-day-old sub-je c t s to discriminate cues fo r place of a r t i c u l a t i o n (/ba/ vs /ga/) and intonation (/ba-/ vs /ba+/, where the "-" denotes a f a l l i n g intonation contour and "+" a r i s i n g intonation contour). In addition to the control group which was presented only with /ba-/, there was a non-speech co n t r o l group which was presented with a stimulus consisting of the acoustic cues which 14 d i f f e r e n t i a t e /ba/ and /ga/. The infants were able to discrim-inate the cues for place and intonation. Moreover, a comparison of the non-speech control condition and the place condition indicated that the infants responded to the acoustic cues for place i n a manner that was considered l i n g u i s t i c a l l y relevant. E i l e r s and M i n i f i e (1974) used the HASP to study infants' discrimination of f r i c a t i v e s between four and seventeen weeks of age. The subjects were found to be able to detect differences between / s / and /v/ and between / s / and /s/ , but not between / s / and /z/. One drawback to the HASP and s i m i l a r paradigms i s that the instances i n which the i n f a n t perceives the s t i m u l i to be d i f f e r e n t but does not f i n d the diffe r e n c e r e i n f o r c i n g cannot be d i f f e r e n t i a t e d . Thus, the inf a n t may have perceived a difference between / s / and /z/, but the r e s u l t s of HASP would not neces-s a r i l y demonstrate t h i s . I f the r e s u l t s of HASP experiments do give r e l i a b l e evidence of the infant's d i s c r i m i n a t i v e c a p a c i t i e s , then E i l e r s and M i n i f i e ' s r e s u l t s would indicate that d i s c r i m i -nation i s dependent on the nature of the acoustic cue rather than on the number of cues a v a i l a b l e . Eleanor Kaplan (1970) used a cardiac habituation-dishabit-uation paradigm to measure the a b i l i t y of four- and eight-month-old children to discriminate r i s i n g and f a l l i n g , stressed and unstressed terminal contours of American English. The four-month-old infants apparently could not discriminate between the stressed or the unstressed versions of the contours. The eight-month-old infants were able to discriminate the r i s i n g stressed 15 a n d f a l l i n g s t r e s s e d c o n t o u r s , b u t t h e y w e r e u n a b l e t o d i s c r i m -i n a t e t h e u n s t r e s s e d c o n t o u r s . B o t h t h e HASP a n d t h e h e a r t r a t e p a r a d i g m s (HRP) h a v e a d v a n t a g e s a n d d i s a d v a n t a g e s ( B u t t e r f i e l d a n d C a i r n s , 1974). The HRP r e q u i r e s l e s s a c t i v e p a r t i c i p a t i o n o n t h e p a r t o f t h e s u b j e c t t h a n t h e HASP. The c r i t e r i o n f o r h a b i t u a t i o n i n t h e HASP i s s t r i n g e n t , w h e r e a s t h e HRP c r i t e r i o n m u s t b e d e c i d e d i n a d v a n c e a n d o c c a s i o n a l l y i n v o l v e s a c e r t a i n amount o f a r b i -t r a r i n e s s . C h a n g e s i n t h e s t a t e o f t h e i n f a n t a r e o f c o n s i d e r -a b l e i m p o r t a n c e i n t h e HRP b u t o f l e s s e r i m p o r t a n c e i n t h e HASP. The i n t e n s i t y o f t h e s t i m u l u s i s i m p o r t a n t i n t h e HRP b u t i s o f l e s s c o n s e q u e n c e i n t h e HASP. F u r t h e r m o r e , t h e HRP i s o n l y a p p l i c a b l e t o v e r y y o u n g s u b j e c t s . The HRP m e t h o d h a s b e e n s t u d i e d i n some d e t a i l ; o n t h e o t h e r h a n d , i n f o r m a t i o n r e g a r d i n g t h e HASP m e t h o d i s l i m i t e d , a n d t h e r e f o r e t h e r e s u l t s o f e x p e r i -m e n t s e m p l o y i n g t h i s m e t h o d m u s t be i n t e r p r e t e d w i t h c a u t i o n . T h e r e i s d e b a t e a s t o w h e t h e r i n f a n t s p e r c e i v e s o u n d d i f f e r e n c e s i n a l i n g u i s t i c a l l y r e l e v a n t m a n n e r , a s s u g g e s t e d b y M o r s e (1972). C h i n c h i l l a s h a v e b e e n t r a i n e d t o r e s p o n d d i f f e r -e n t i a l l y t o p r e s e n t a t i o n s o f / i / v s / a / ( B u r d i c k a n d M i l l e r , 1974), / t / v s / d / (Kuh'l a n d M i l l e r , 1974), / p a / v s ' / b a / a n d / g a / v s / k a / ( K u h l a n d M i l l e r , 1975). The m e t h o d e m p l o y e d i n t h e s e e x p e r i m e n t s was a v a r i a t i o n o n t h e HASP t e c h n i q u e , w h i c h r e q u i r e d t h e a n i m a l s t o jump a c r o s s a c a g e a n d l i c k o n a w a t e r t u b e . T h e s e s t u d i e s s u g g e s t t h a t w h a t may b e a c t u a l l y b e i n g t e s t e d i n i n f a n t s i s a n a b i l i t y t h a t i s s o m e t h i n g o t h e r t h a n 16 previously claimed and which somehow re l a t e s to the way i n which the brain processes sound. Another recent study of stop discrimination i n Kikuyu ch i l d r e n (Streeter and Landauer, 1975) casts further doubt on some of the findings of infant speech perception research. The Kikuyu language distinguishes prevoiced and voiced stops but has no stop comparable to the English /p/. Kikuyu c h i l d r e n were able to discriminate not only prevoiced from voiced l a b i a l s , but also voiced from voiceless l a b i a l s , even though the l a t t e r are not phonemically d i s t i n c t i n the Kikuyu language. A f t e r the children received formal teaching i n English, the voiced/voiceless d i s -crimination improved. If experience with a language i s of major importance i n discrimination, then the theory that infants are discriminating voiced and voiceless stops on the basis of voice onset time alone i s l i k e l y to be in c o r r e c t ; i n f a c t there i s evidence to indicate that formant t r a n s i t i o n frequencies and rates are more important than voice onset time. I t would seem that Kaplan and Kaplan's suggestion that the infant's perception of suprasegmental information precedes that of segmental i n f o r -mation i s probably correct. A recent k i n e s i c study purports to demonstrate that neonatal movement i s i n synchrony with adult speech (Condon and Sander, 1974). A frame-by-frame analysis of infant movement occurring as an adult (either l i v e or taped) spoke to the infant was said to reveal correspondences between the movement of the i n f a n t and the sound patterns of the speech of the adult. The authors' 17 conclusions are questionable for a number of reasons: They make no mention of the co a r t i c u l a t o r y e f f e c t s which are present i n speech; simply put, i n connected speech, while one phoneme i s being produced, the a r t i c u l a t o r s are moving into p o s i t i o n for the production of the next phoneme. The phoneme being produced i s thus influenced to a ce r t a i n degree by the succeeding phoneme. As a r e s u l t , i n t e r a l i a , no two phonemes are ever produced i n exactly the same manner. The infant l i s t e n e r i s exposed to a constantly changing stream of speech; changes are occurring not only across but also within phoneme boundaries. The authors' representation of s i m i l a r sounds over several f i l m frames i s therefore not as accurate as i t could have been had a f i n e r t r a n s c r i p t i o n been used. Another c r i t i c i s m of the study involves d i f f e r e n t movement configurations of the i n f a n t and t h e i r re-lat i o n s h i p to the adult speech. In some instances i t appears that movements are sustained over a number of successive sounds, while i n other cases some or a l l of the movements may change i t h each sound. In the one sample presented i n the paper, these changes appear to be of a random nature. For example, the word 'over appears twice i n the sample given: [ o v t r ] f i r s t and [ oveJ ] second. During the presentation of [ o v t r ] , the c h i l d ' s movements change with each phoneme, yet during the next [ o v a J ] , the c h i l d ' s movements remain constant. The r e s u l t s and authors' i discussion leave many questions unanswered and r a i s e others i n addition. An examination of k i n e s i c factors should prove very valuable i n the study of language a c q u i s i t i o n , but the r e s u l t s need to be examined and evaluated more thoroughly than i s the 18 case i n the report by Condon and Sander. 1.22. Productive capacity: The i n f a n t larynx In the previous section we noted that the hearing mechanism i s well developed at b i r t h . On the other hand, as w i l l now be discussed, the vocal apparatus i s not f u l l y developed at b i r t h . Its immature status places some l i m i t a t i o n s on the infant's vocal output but acts b e n e f i c i a l l y i n ways that are important for s u r v i v a l . The i n f a n t larynx can be simply described as a single-tube resonating system rather than as a two-tube responating system (as i s found i n the ad u l t ) . In a recent a r t i c l e , Lieberman, C r e l i n and K l a t t (1972) compared the s k u l l features and vocal t r a c t s of the human neonate, the adult human, the chimpanzee and a reconstruction of Neanderthal man. A number of anatomical features were found to be s i m i l a r i n newborn, chimpanzee and Neanderthal man, but d i f f e r e n t i n the adult human. In the adult human, the posterior t h i r d of the tongue rests i n a v e r t i c a l p o s i t i o n and forms the anterior wall of the pharyngeal cavit y . In the other three vocal t r a c t s , the tongue i s e n t i r e l y within the o r a l c a v i t y when i n i t s neutral p o s i t i o n . At the same time, the hard palate i s r e l a t i v e l y f l a t , whereas i t i i s arched i n the adult human. In the newborn, chimpanzee and Neanderthal man, the e p i g l o t t i s can a r t i c u l a t e with the soft palate. Since the opening of the larynx into the pharynx i s immediately behind the o r a l c a v i t y , there i s v i r t u a l l y no 19 supralaryngeal portion of the pharynx. The high p o s i t i o n of the e p i g l o t t i s makes closure of the o r a l c a v i t y possible during feeding to allow for breathing through the nose. In the adult, there i s no such approximation of the e p i g l o t t i s and s o f t palate, and the opening of the larynx into the pharynx i s such the one-ha l f of the supralaryngeal c a v i t y i s formed by the pharyngeal cavity . At b i r t h , the larynx i s t i l t e d i n a posterior d i r e c t i o n (Kirchner, 1970). With the growth process, i t becomes more>in l i n e with the trachea and more angulated with respect to the nasal passages and the mouth. As these modifications occur, the larynx evolves into a two-tube resonating system. Due to i t s t i l t , the in f a n t larynx i s a c t u a l l y a more e f f i c i e n t r espiratory organ, since the pathway to the lungs i s more d i r e c t than i n the adult. The infant larynx, then, i s not a miniature adult larynx: I t i s softer, more p l i a b l e than the adult larynx and i s proportionately smaller i n r e l a t i o n to the size of other struc-tures i n the body. Moreover, i t i s situated i n a higher p o s i t i o n i n the neck r e l a t i v e to the adult larynx; descent of the larynx begins during embryonic l i f e and continues u n t i l the adult p o s i t i o n i s reached at about ten years of age (Wind, 1970). The vocal f o l d s , which are approximately 3 mm long at b i r t h , reach a length of 5.5 mm by the age of one year. The r a t i o of vocal f o l d length to anteroposterior diameter of the larynx i s 20 1:2.3 i n the infant as compared to 1:1.5 i n the adult female and 1:1.3 i n the adult male (Kirchner, 1970). The adult female r a t i o of 1:1.5 i s reached i n the inf a n t by nine months. The high r a t i o i n the infant indicates that there i s some c o n s t r i c t i o n of a i r flow. When an adult inhales deeply, the opening of the g l o t t i s i s almost equal i n size to the lumen of the trachea; there i s no obstruction of a i r . In the infa n t , the g l o t t a l opening cannot approximate the siz e of the lumen of the trachea during i n s p i r a t i o n . Since the inf a n t can only take i n a small volume of a i r with each breath, the rate of r e s p i r a -t i o n i s rapid. In v o c a l i z a t i o n , only a small area of the vocal folds i s available for v i b r a t i o n . The sounds so produced by the infant are therefore much higher pitched than those of the adult. Further, i t i s possible that u n t i l an approximation of the adult female r a t i o of 1:1.5 i s reached, the a b i l i t y of the infa n t to b u i l d up and release subglottal pressure, as for stop consonants, may be somewhat r e s t r i c t e d . Studies of the motions of the infant vocal t r a c t during crying suggest that mature patterns of movement are very r a p i d l y established and some are present even at b i r t h (Menyuk, 1971, pp. 45-47). The rudiments of c o a r t i c u l a t o r y a c t i v i t y are seen i n the infant's a n t i c i p a t i o n of the cry: the structures are i n p o s i t i o n before the crying begins. The infant gradually learns to use the tongue, l i p s and s o f t palate to modify the configu-r a t i o n of the vocal t r a c t and produce d i f f e r e n t sounds. 21 1.23. Cognitive development and i m i t a t i o n i n the Sensorimotor  Period T r a d i t i o n a l l y , the infant has been regarded as a helpless human being, incapable of any form of i n t e l l e c t u a l a c t i v i t y . Piaget was one of the f i r s t to put f o r t h strong t h e o r e t i c a l notions regarding the infant's cognitive development. Central to his theory i s the idea that i n t e l l e c t u a l development i s a 'continual process of organization and reorganization of struc-ture, each organization integrating the previous one into i t s e l f ( P h i l l i p s , 1969, pp. 10-11). The s t r u c t u r a l units of the theory are known as schemata. Sensory input i s fed into the schemata which are, i n turn, modified by the input. Integral to Piaget's theory are three major periods of cognitive development, roughly delimited as follows: the Sensorimotor Period (birth to 2 years), the Concrete Operations Period (2 to 11 years), and the Formal Operations Period (11 to 15 years). For the purposes of t h i s t h e s i s , we are concerned with the Sensorimotor Period. The Sensorimotor Period i s composed of six stages, each of which i s named for the process which has most recently become operative. I t i s recognized that each c h i l d w i l l pass through these stages at his/her own rate. D The f i r s t stage i s a b r i e f one, l a s t i n g from b i r t h to about one month. During t h i s time, the infant's a c t i v i t y i s l a r g e l y r e f l e x i v e i n nature, whereby the b u i l t - i n schemata are exercised. 22 The second stage, which begins at one month and l a s t s u n t i l about four months, involves egocentric a c t i v i t i e s which are continually repeated. New stimulus patterns are established and incorporated into the e x i s t i n g schemata. At f i r s t , the i n f a n t would appear to respond to a l l objects i n an indiscriminate manner. In time, d i f f e r e n t i a l responses such as smiling at some objects, and touching or sucking others, begin to appear. The behaviour of the infant begins to become object-centered, but there i s no general space or time, and no object permanence; there are only events. In other words, when an object disappears from view, i t no longer e x i s t s for the i n f a n t . In stage three, occurring between four and eight months, there i s continual development and refinement of the schemata developed i n stages one and two. Motor responses become more b r i e f . The action appears to represent the object i t s e l f . This i s motor meaning: the responses that the c h i l d makes to an object are e f f e c t i v e l y , the meaning of that object. New objects are incorporated into the e x i s t i n g schemata. The c h i l d begins to engage i n b r i e f searching for absent objects. This stage then, marks the beginning of object permanence. The fourth stage represents a continual refinement of stage three and a p p l i c a t i o n of r e f i n e d responses to new s i t u a t i o n s . This stage begins when the c h i l d i s about eight months of age and l a s t s u n t i l approximately one year. There i s the beginning of 'context-bound object permanence'. That i s , the r e a l i t y of the object begins to be dependent on the surrounding rather than 23 on the infant's actions. In the realm of c a u s a l i t y , the i n f a n t i s now capable of perceiving agents other than s e l f as causes of events. Between twelve and eighteen months of age (stage five) the in f a n t begins to experiment; he/she manipulates the environment i n order to determine the r e s u l t of his/her actions. Object permanence, space perception, and time perception continue to develop. Means that are found to be i n e f f e c t i v e are dropped, from the e x i s t i n g schemata. The s i x t h and f i n a l stage of the Sensorimotor Period i s a t r a n s i t i o n a l stage to the pre-operational subperiod of the Concrete Operational Period. During the l a t t e r h a l f of the second year of l i f e , the c h i l d increases his/her use of i n t e r n a l symbols. On the basis of past experience he/she invents new methods of dealing with the environment and i s able to ant i c i p a t e the r e s u l t s of his/her actions. S i n c l a i r (1971) puts f o r t h a strong argument for the use of cognitive structures i n explaining language a c q u i s i t i o n rather than the reverse. She states that once the c h i l d has established s p a t i a l displacement and object permanence, he/she i s now an active person. That the c h i l d manifests the a b i l i t y to foresee future r e s u l t s on the basis of present actions i s i n d i c a t i v e of symbolic thought. The features of language which express a f f e c t i v e states (stress, melody, duration and intensity) are present i n the 24 c h i l d ' s language at a very early stage. S i n c l a i r believes that these features are incorporated by im i t a t i o n 'before the f i r s t d i s c r e t e , meaning-bearing elements occur' (p. 126). Piagetian theory attempts to trace the development of imita t i o n which Furth (1969) defines as 'The f i g u r a t i v e correspondence of motor a c t i v i t y to an i n t e r n a l event. Imitation has three stages: (1) sensory-motor i m i t a t i o n , i d e n t i c a l with perceptual accommodation, (2) deferred i m i t a t i o n (gesture) i n the absence of the model, the beginning of symbol formation, (3) i n t e r n a l i z e d i m i t a t i o n , the image'. (p. 261) Although t h i s d e f i n i t i o n encompasses many forms of im i t a t i o n , we are concerned here with the development of vocal i m i t a t i o n . According to Piagetian theory, true i m i t a t i o n i s pure accom-modation. The appearance of 'pseudo-imitation' i n stage two i s thought to be a stage preliminary to the development of 'true' i m i t a t i o n . When an i n d i v i d u a l repeats an action that the c h i l d has j u s t performed and then the c h i l d repeats that action, pseudo-imitation has occurred. In stage three, the infant imitates movements and sounds that are within his/her repertoire and v i s i b l e on his/her own body. Mounoud (1974) c i t e s the work of Olga Maratos, whose four-month-old subjects were able to imitate mouth movements. By stage four, the r e s t r i c t i o n s involving the imitation of only v i s i b l e movements and c e r t a i n sounds are l i f t e d . The infant becomes interested i n novel 25 a c t i v i t i e s and t h e i r i m i t a t i o n . The i m i t a t i o n i n stage f i v e i s of a more precise nature than before; Furthermore, patterns that are less s i m i l a r to the established schemata are reproduced. Stage six marks the beginning of i m i t a t i o n of non-human, even non-living objects, as well as the i m i t a t i o n of absent objects, known as deferred i m i t a t i o n . Imitation of complex actions i s c a r r i e d out with less d i f f i c u l t y than previously. Lewis (1951) c i t e s Guernsey's (1928) study of im i t a t i o n involving 200 c h i l d r e n aged two months to twenty-one months. Using Guernsey's study and observations from f i v e other records, Lewis divides the c h i l d ' s progress into three stages. These stages are, to a c e r t a i n extent, compatible with Piaget's framework of i m i t a t i o n . The f i r s t year i s divided into three stages, the f i r s t one l a s t i n g from b i r t h to four months, the second occurring from four months of age to nine months, and the t h i r d stage beginning at about nine months. During the f i r s t stage, the i n f a n t responds to human speech by making sounds that are within his/her own r e p e r t o i r e . Occasionally, the c h i l d ' s imitated version resembles the intonational and phonetic form of the o r i g i n a l . During stage two, vocal responses to speech either disappear completely or occur r a r e l y , and do not reappear u n t i l stage three. In stage three, the c h i l d seems to focus on the a c t i v i t y of imitation i t s e l f . There i s a gradual change from the imitation of f a m i l i a r to unfamiliar sounds and sound groups. Intonational forms are reproduced i n a more precise manner than previously, since the i n f a n t seems to be attending to p i t c h and stress patterns. 26 1.24. B i o l o g i c a l l y based theories of infant v o c a l i z a t i o n In addition to Piaget's ideas on language development which are c o g n i t i v e l y based, there are theories about the nature and development of speech and language which have a p h y s i o l o g i c a l basis. Lieberman (1967) postulates that the infant's c r i e s have as t h e i r basis a 'hypothetical innate r e f e r e n t i a l breath-group'. The adult counterpart i s the archetypal normal breath-group which produces an intonational pattern that i s c h a r a c t e r i s t i c of the unemphatic dec l a r a t i v e sentence i n English, whereby fundamental frequency and acoustic amplitude f a l l at the end of the sentence; the notation [-BG], designating the unmarked breath-group, i s used to denote t h i s r i s i n g - f a l l i n g pattern. Experimentally, the measurement of esophageal pressure i s used to i n f e r the r e l a t i v e l e v e l of subglottal a i r pressure. When the esophageal pressure f a l l s , s u bglottal pressure f a l l s ; and when esophageal pressure r i s e s , subglottal pressure can also be i n f e r r e d to have r i s e n . The shape of the fundamental frequency contour of the infant's cry approximates that of the t y p i c a l esophageal pressure contour which r i s e s i n i t i a l l y , l e v e l s o f f somewhat and then f a l l s abruptly. In conclusion, 'the gross var i a t i o n s of the fundamental frequency contour thus seem to be a function of the subglottal a i r pressure during infant c r i e s ' (1967, p. .43) . Kim (1968) has strongly c r i t i c i z e d Lieberman 1s hypotheses. He claims that r e s p i r a t i o n i s innate, but that the infant's 27 cry i s not innate to speech. He argues that c o n t r o l l e d sub-g l o t t a l pressure, which can only come about as a r e s u l t of the development of muscular c o n t r o l , i s a prereq u i s i t e to speech phonation. Since the inf a n t does not yet have the a b i l i t y to control subglottal a i r pressure, the inf a n t cry cannot be regarded as a speech phonation. The evidence of Wolff (1969) would tend to refute Kim's claims. In a phonetic study of babbling i n his twin daughters, Cruttenden (1970) noted that h i s r e s u l t s did not support Lieberman's breath-group hypothesis or the f i n a l f a l l of fundamental frequency within the breath-group. He found that as early as three months, f a l l i n g - r i s i n g intonation patterns were included i n the repertoires of both babies; some other variations occurred, but Cruttenden did concede that f a l l i n g patterns predominated. The r e s u l t s of Wasz-Hockert et a l . (1968) lend p a r t i a l support to Lieberman's claims. F a l l i n g and r i s i n g - f a l l i n g contours were the most frequent patterns i n pain and hunger c r i e s , r e s p e c t i v e l y . The b i r t h cry was marked by a r e l a t i v e l y high proportion of f a l l i n g patterns. From one to seven months, the pleasure cry was characterized by l e v e l and r i s i n g - f a l l i n g contours. It i s generally agreed that intonation i s one of the f i r s t features to appear i n children's speech (Shvachkin, 1948; R a f f l e r Engel, 1965; Lewis, 1951; Lenneberg, 1967; Lieberman, 1967; Tonkova-Yampol'skaya, 1969; C r y s t a l , 1972, 1973a, 1973b). The 28 f i r s t patterns are s i m i l a r to those occurring over whole sen-tences (Raffler Engel, 1965; Lenneberg, 1967; Tonkova-Yampol 1skaya, 1969). Later on, patterns, such as may occur over a word, appear (Raffler Engel, 1965). Shvachkin (1948) states that '"the meaning" represented by the complex experience of denotative, a f f e c t i v e , and functional s i m i l a r i t y of perceived objects i s a semantic u n i t of the e a r l i -est c h i l d speech' (p. 93). He c i t e s several instances of the semantic function of intonation i n both comprehension and expression. Rhythm i s said to acquire a s p e c i a l semantic func-t i o n at about s i x months. Lenneberg, Rebelsky and Nichols (1965) suggest that crying and the appearance of cooing are governed by maturational fac-t o r s . A comparison of the vo c a l i z a t i o n s produced by ch i l d r e n of hearing parents and children of deaf parents revealed no essen-t i a l differences up to the age of three months. This was even true of one subject who was l a t e r discovered to be deaf. A wider range of crying behaviour was reported i n the c h i l d r e n of deaf parents. I t was thought that t h i s was l i k e l y a r e f l e c t i o n of the acoustic s t i m u l i present i n the homes of the deaf f a m i l i e s and of the inconsistencies i n the response of the deaf parents to the c r i e s of t h e i r infants. Although a l l of the deaf f a m i l i e s had sound-to-light transducing devices, the arrangement d i f f e r e d from home to home. These devices would cause a l i g h t to f l a s h i f the noises made by the baby were greater than a given inten-s i t y l e v e l . In some homes a l i g h t would f l a s h only i n one room, 2 9 whereas i n one home l i g h t s were set up at d i f f e r e n t places with-i n the house. In two other homes, the l i g h t would f l a s h i l l u -minating the baby's room, as w e l l as h i s face. Ramey and Hieger (1972) discuss the p o s s i b i l i t y of the f l a s h i n g l i g h t acting as a r e i n f o r c i n g stimulus for the babies' v o c a l i z a t i o n s . There are many theories which have been developed to ex-p l a i n why the infant vocalizes (e.g. Mowrer's autism theory, feedback theories). Since there i s l i t t l e d e f i n i t i v e evidence bearing on explanatory p r i n c i p l e s , an examination of these theories w i l l not be attempted here. 1.25. Methods used i n the study of i n f a n t v o c a l i z a t i o n s While some investigators have chosen to theorize about language a c q u i s i t i o n i n the i n f a n t , others have chosen to c o l l e c t data on the subject. Several approaches have been employed i n the past for the c o l l e c t i o n of data on i n f a n t utterances. Early observations were contained i n d i a r i e s (Darwin, 1877; Lewis, 1951). Much of t h i s data i s extremely valuable from a de s c r i p t i v e standpoint; however, i n many cases the author's own c h i l d was involved, and thus some of the accounts are not as objective as they might otherwise have been. , Irwin and Chen (1946) conducted a l o n g i t u d i n a l study of phonemic development i n in f a n t s . The subjects were observed i n t h e i r homes, and vocalizations that occurred on t h i r t y breaths or respirations were transcribed using a modification of the International Phonetic Alphabet. This method was l i k e l y the 30 best possible i n view of the recording equipment that was av a i l a b l e at the time; however, now that e f f i c i e n t , high-quality equipment i s a v a i l a b l e , other methods of data c o l l e c t i o n have become more popular. Furthermore, the study was c r i t i c i z e d by Lynip (1951) for the use of the IPA, a system used to transcribe mature speech, i n describing infant utterances: " . . . i t i s t o t a l l y impractical to t r y to express i n adult sounds an utterance of an infant p r i o r to his speech maturation. Infant utterances are not l i k e any of the well defined values of adult language. They are produced d i f f e r e n t l y and they are shaped d i f f e r e n t l y , t h e i r r e l a t i o n s h i p s with adult sounds are at f i r s t only f o r t u i t o u s . Infant sounds cannot be described except i n terms of themselves. There i s no International Phonetic Alphabet for the utterances of a baby. 1 (p. 226) In order to overcome some of the problems of human error i n the analysis of speech, Lynip used a magnetic tape recorder i n combination with the sound spectrograph for the analysis of one infant's vocalizations throughout the f i r s t year of l i f e . Winitz (1960) contended without reasonable cause or corrobora-t i v e evidence, that Lynip's assumption regarding the use of phonetic t r a n s c r i p t i o n systems and the f a l l i b i l i t y of the human ear was . ' i l l o g i c a l and unwarranted' [sic] (p. 179). Ten graduate students i n speech pathology were asked to transcribe a sample of infant vowel sounds. Thirty-one vowels agreed on by more than seven judges were subjected to spectrographic analysis. 31 Graphic p l o t s of Formant 1 vs Formant 2 revealed a displacement of the thus constructed vowel t r i a n g l e upward and to the r i g h t of the standard adult t r i a n g l e . There was some overlap of formant frequencies of the d i f f e r e n t vowels, and considerable v a r i a t i o n was observed. Winitz appears to have misunderstood Lynip's basic tenet regarding the f a l l a c y of describing i n f a n t s ' sounds i n terms of an adult model. It i s generally recognized by present-day l i n g u i s t s that the production of an IPA for infant utterances i s a formidable task, and many have been experimenting with more d e s c r i p t i v e frameworks (Gruber, 1966; Bullowa, Jones and Bever, 1964; Ringwall, Reese and Markel, 1965; Stark and Rose, 1974; Bush et a l . , 1973). Ring-wall, Reese and Markel (1965) analyzed the v o c a l i z a t i o n s of f o r t y three-day-old infants using d i s t i n c t i v e features: The r e l i a b i l i t y of t h i s method was high (although i t s v a l i d i t y may be suspect), and i t s use appears j u s t i f i e d since i t does not impose a r i g i d adult model on a developing system. Bullowa, Jones and Bever (1964) u t i l i z e d a somewhat d i f f e r e n t method: Developmental observations were made of neurological and sensory responses to v i s u a l , auditory, t a c t i l e and k i n e s t h e t i c s t i m u l i , a l l observations being documented on f i l m . Half-hour sessions of spontaneous.activity of the subjects i n t h e i r homes .. were tape- and film-recorded; an observer d i c t a t e d the f i n e r de-t a i l s of the i n f a n t s ' behaviour that could not be captured by the camera. These data were to have been re-synchronized i n the pro-cessing stage. Additional information regarding recent events oc-curring i n the household and about the i n f a n t s ' condition was c o l -l e c t e d . The authors hoped to determine the development of para-l i n g u i s t i c features such as tone of voice, loudness and rhythm, 32 as well as the development of phonemic features (for which a l i n -g u i s t was devising a notation). They also wished to determine the mutual influence of the mother's and c h i l d ' s patterns of speech. A further aim was to discover whether there were any consistent r e l a t i o n s h i p s between the development of vocal to verbal behaviour and other behaviour patterns. The r e s u l t s of t h i s study have not been published to date; i t appears that such a mass of information was assembled that analysis and ultimate synthesis of the data be-came too formidable, and the study was e s s e n t i a l l y abandoned. The sound spectrograph, as noted e a r l i e r , provides an objec-t i v e method fo r examining speech and i s invaluable for the analy-s i s of infant v o c a l i z a t i o n s . Nevertheless, i t s use with large samples i s laborious and time-consuming. A l t e r n a t i v e l y , computer-ized a n a l o g - t o - d i g i t a l devices have been used suc c e s s f u l l y by Sheppard and Lane (1968) i n the analysis of utterances c o l l e c t e d i n a sound-proof s e t t i n g ; however, t h e i r technique i s not a p p l i c a -ble to data gathered i n a normal home environment, since a v a i l a b l e instrumentation i s incapable of f i l t e r i n g out background noise. 1 . 2 6 . Studies of i n f a n t vocal output Irrespective of method, there i s an ever increasing amount of information a v a i l a b l e on infant v o c a l i z a t i o n s . These studies can be divided into two major categories: (1) acoustic a t t r i b u t e s , and, s p e c i f i c a l l y , (2) intonation patterns. 1 .261 . Acoustic studies A great number of studies have been devoted to the character-i z a t i o n of crying utterances, since i t has been established that the q u a l i t y of the newborn infant cry can be used i n determining the presence or absence of abnormalities such as brain damage 33 and c e r t a i n genetic disorders such as Down's Syndrome and the C r i du Chat Syndrome (Wasz-Httckert et a l . , 1968). Infants who have experienced anoxia at b i r t h also e x h i b i t abnormal crying patterns for some time a f t e r b i r t h . Vuorenkoski et a l . (1971) established a r a t i n g system for inf a n t pain cry responses which could be used to assess the degree of abnormality of the cry. There was a strong correspon-dence between the cry score and diagnosis. Measures of the cry score over time revealed the p o s s i b i l i t y of the use of the r a t i n g system i n following the c l i n i c a l course of c e r t a i n diseases. Fairbanks (1942) analyzed the fundamental frequency charac-t e r i s t i c s of the hunger c r i e s of his i n f a n t son. On each monthly birthdate for the f i r s t nine months of h i s l i f e , the baby was deprived of his regular two o'clock feeding; the ensuing c r i e s were recorded and analyzed. The mean fundamental frequency recorded was 556 Hz, and a range i n frequency from 63 Hz to 2631 Hz was observed over the nine-month period. A rapid increase i n fundamental frequency occurred during the f i r s t h a l f of the nine-month period. This was followed by smaller, i r r e g u l a r changes i n the second half of the observation period. The author plo t t e d frequency d i s t r i b u t i o n s of the fundamental frequencies produced by the infant at each month. The d i s t r i b u -t i o n at one month resembled a normal curve, but the subsequent d i s t r i b u t i o n s were more i r r e g u l a r and of higher v a r i a b i l i t y . In h i s account of the natural h i s t o r y of crying based on observations of eighteen inf a n t s , Wolff (1969) describes a basic 34 cry, from which he contends a l l other cry and non-cry v o c a l i z a -tions evolve. A rhythmical cry, often c a l l e d the hunger cry, i s observable within one-half hour of b i r t h and consists of a cry (600 msec), a period of s i l e n c e (200 msec), a short i n s p i r a t o r y whistle (100-200 msec) of a higher fundamental frequency than the f i r s t cry, and then a b r i e f r e s t before the i n i t i a t i o n of the next cry cycle (p. 82). The fundamental frequency of t h i s cry ranges from 250 to 450 Hz with a strong band of energy between 350 and 400 Hz. Fundamental frequency r i s e s s l i g h t l y at the beginning of the cry and then tapers o f f towards the end. o A v a r i a t i o n on the basic cry i s the 'mad1 or 'angry' cry, which has the same temporal sequence but i s turbulent due to excess a i r being forced through the vocal f o l d s . The pain cry i s characterized by a sudden onset of long, loud crying, and an 'extended'. period of 'breath holding i n e x p i r a t i o n ' , followed by an i n s p i r a t o r y gasp (p. 85). Subsequent c r i e s vary i n duration, and the infant eventually c r i e s according to the basic pattern previously described. The cry of f r u s t r a t i o n , such as may occur following the removal of a p a c i f i e r , i s characterized by a cry ( i n i t i a l l y long and drawn out) followed by an i n s p i r a t o r y whistle. While knowledge of the crying behaviour of infants has advanced considerably over the past decade, the topic of non-crying utterances has been serio u s l y neglected. In an i n v e s t i -gation of speech development i n Japanese i n f a n t s , Murai (1960) noted that the f i r s t non-crying utterances appeared at 1.5 months. Spectrograms of these utterances revealed considerable energy at 35 the lower frequencies, while the higher frequencies sometimes contained no energy whatsoever. The average duration of such utterances was under 400 msec. These early utterances were c l o s e l y r e l a t e d to respiratory rhythms. Later, i n the babbling stage, utterances became shorter i n length and thus somewhat independent of respiratory a c t i v i t y . A study (Nakazima, 1962), involving Japanese and American i n f a n t s , confirmed the appear-ance of non-crying utterances at the age of about one month. The rhythm of phonation was observed to be greater than that of r e s p i r a t i o n with one period of phonation l a s t i n g from 600 to 800 msec, while one period of r e s p i r a t i o n l a s t e d from 400 to 600 msec. Wolff (1969) observed that new non-cry patterns f i r s t appear j u s t before the infant begins to fuss. These patterns are l a t e r practiced when the infant i s i n a contented state, 'but u n t i l at l e a s t the end of the t h i r d month, vocal novelties appear as i f they were discovered only i n the context of moderate discomfort, became autonomous from a p a r t i c u l a r state by repeated p r a c t i c e , and then were incorporated into the ensemble of non-cry v o c a l i -zations' (p. 99). Non- cry v o c a l i z a t i o n s are c h a r a c t e r i s t i c a l l y more complex and of longer duration than rhythmical c r i e s . The fundamental frequency may be doubled or halved i n the middle of the utterance and the terminal portion usually has a l e v e l or a r i s i n g fundamental frequency according to Wolff's d e s c r i p t i o n . Sheppard and Lane (1968) investigated the prosodic features of fundamental frequency, duration and amplitude i n the 36 v o c a l i z a t i o n s of two infants, one male and one female. Con-tinuous recordings of the infants' v o c a l i z a t i o n s were made from the time of b i r t h u n t i l the age of f i v e months. The material c o l l e c t e d was sampled and processed using analog e l e c t r o n i c devices. The fundamental frequency of the male i n f a n t dropped from 438 Hz at b i r t h to 411 Hz at twenty-one days, then rose again to 455 Hz by f o r t y - f i v e days, and s t a b i l i z e d at approximately t h i s value for the remainder of the study. The fundamental frequency of the female in f a n t dropped from 4 01 Hz at b i r t h to 384 Hz at twenty-one days and then rose to 420 Hz by f o r t y - f i v e days, where i t likewise s t a b i l i z e d for the duration of the study. C o e f f i c i e n t s of v a r i a t i o n were computed between and within utterances for each of the prosodic parameters. The c o e f f i c i e n t s of v a r i a t i o n i n fundamental frequency both between and within utterances remained e s s e n t i a l l y constant. Thus, the fundamental frequency of the in f a n t d i d not vary more (or less) between or within utterances with age. In f a c t , approximately two-thirds of the readings of fundamental frequency for a p a r t i c u l a r utterance were within ten percent of the mean value. The average c o e f f i c i e n t of v a r i a t i o n i n amplitude within utterances stayed nearly constant; however, the v a r i a b i l i t y i n amplitude within utterances was greater than the v a r i a b i l i t y i n fundamental frequency within utterances. The arithmetic and geometric means f o r duration were, re s p e c t i v e l y , 550 msec and 290 msec for the male and 552 msec and 286 msec for the female. The 37 differences between the two means for each subject were present ostensibly as a r e s u l t of the highly p o s i t i v e skewness of the frequency d i s t r i b u t i o n s of the utterance durations. The c o e f f i c i e n t of v a r i a t i o n i n duration between utterances decreased with age, i n d i c a t i n g that the average duration of utterances within a sample s t a b i l i z e d with age. The values for the duration of the average utterance reported by Sheppard and Lane correlate f a i r l y well with those of Murai (400 msec) and Nakazima (600-800 msec). Ringwall, Reese and Markel (19 65) found that the average i n f a n t utterance was shorter than 350 msec. Any v a r i a t i o n i n these values i s due to the difference i n age of the subjects and the frequencies of occur-rence of d i f f e r e n t lengths of c r i e s . Handford (19 72) found that the duration of non-cry utterances increased exponentially with age. A drawback to the Sheppard and Lane study i s that the r e -cording environment was not a natural one. The infants were kept i n p l e x i g l a s s a i r c r i b s , since these afforded a more optimal environment i n terms of attenuation of outside noises. Many of the i n t e r a c t i o n a l sequences which might have occurred i n a more normal s i t u a t i o n were therefore not possible to obtain. i Furthermore, since there were only two subjects involved i n the experiment, one must be wary of generalizing with respect to the r e s u l t s . Moreover, no attempt was made i n the computer analysis to d i s t i n g u i s h cry and non-cry v o c a l i z a t i o n s . Yet, i n explaining 38 the possible sources of developmental trends, the authors a t t r i b u t e the i n i t i a l l y high fundamental frequency to the f r e -quency of unconditioned-reflex crying responses. I t i s suggested that t h i s type of crying decreases i n frequency with age, as does the fundamental frequency. Following t h i s , a new class of operant c r i e s appears, c o n t r o l l e d by environmental events. One would have to separate the r e s u l t s for the two types of v o c a l i z a -tions i n order to determine whether t h i s idea i s tenable. A second explanation regarding a possible source of a developmental trend involves the idea that increases i n area, thickness, and length of the vocal folds with age would lead to an i n i t i a l drop i n fundamental frequency. The successive occurrence of an increase i n s u b g l o t t a l pressure with age would r e s u l t i n an increase i n fundamental frequency. Fairbanks (1942) postulated that the increase i n fundamental frequency must be due to 'variation i n vocal f o l d tension rather than of v a r i a t i o n i n length and thickness' (p. 231). He suggests that t h i s may be r e l a t e d to psychological conditions or, those being constant, to an increased c a p a b i l i t y to exert muscular tension i n and adjacent to the larynx. This, he notes, i s i n agreement with the rapid neuromuscular development^ which takes place during the f i r s t year of l i f e . He postulates that the plateau i n fundamental frequency could be a t t r i b u t e d to the negative acceleration of neuromuscular growth coincident with the less negatively accelerated continuation of dimensional growth. In view of what i s known of the mechanisms of laryngeal action and of laryngeal development during early l i f e , any explanation of the f l u c t u a t i o n 3 9 o f f u n d a m e n t a l f r e q u e n c y i n t h e f i r s t y e a r w o u l d h a v e t o b e b a s e d o n a c o m b i n a t i o n o f t h e i d e a s p r e s e n t e d a b o v e . H a n d f o r d ( 1 9 7 2 ) s t u d i e d t h e d e v e l o p m e n t o f f u n d a m e n t a l f r e -q u e n c y , w i t h i n - u t t e r a n c e r a n g e a n d d u r a t i o n i n t h e n o n - c r y u t t e r a n c e s o f s i x f i v e t o 1 5 - w e e k - o l d i n f a n t s . T w o t r e n d s w e r e e v i d e n t i n h e r d a t a : t h e f i r s t w a s a n e x p o n e n t i a l i n c r e a s e o f d u r a t i o n w i t h a g e , a n d t h e s e c o n d w a s a l i n e a r i n c r e a s e o f w i t h i n -u t t e r a n c e r a n g e w i t h a g e . W i t h i n - u t t e r a n c e r a n g e w a s f o u n d t o b e d e p e n d e n t o n t h e a m o u n t o f f l u c t u a t i o n a n d t h e d u r a t i o n o f t h e u t t e r a n c e . A c r i t i c i s m o f t h e s e f i n d i n g s i s t h a t u t t e r a n c e s w e r e a n a l y z e d i r r e s p e c t i v e o f t h e i n t o n a t i o n c o n t o u r w h i c h t h e y e x h i b i t e d . T h i s m a y w e l l h a v e o b s c u r e d s o m e i m p o r t a n t t r e n d s w i t h r e s p e c t t o t h e v a r i a b l e s s t u d i e d a n d t o t h e s t a t i s t i c a l t e s t s ( n o t e d a b o v e ) c a r r i e d o u t . F u r t h e r m o r e , t h e v a r i a b l e o f d u r a t i o n w a s n o t i n c l u d e d i n t h e s t a t i s t i c a l a n a l y s i s ; t h i s v a r i a b l e m a y b e i m p o r t a n t i n t e r m s o f i n f a n t s ' v o c a l r e a c t i o n s t o o b j e c t s . 1 . 2 6 2 . I n t o n a t i o n s t u d i e s T h u s f a r w e h a v e d i s c u s s e d s o m e o f t h e i s o l a t e d a c o u s t i c f e a t u r e s o f t h e s p e e c h s i g n a l o f t h e i n f a n t . G i v e n a c e r t a i n b e h a v i o u r a l c o n t e x t , t h e i n f a n t m o d i f i e s h i s / h e r , v o c a l o u t p u t , s u c h t h a t d i f f e r e n t s t a t e s a p p e a r t o b e c h a r a c t e r i z e d b y s p e c i f i c " g r o u p i n g s ' o f a c o u s t i c f e a t u r e s . I n f o r m a t i o n r e g a r d i n g a c t u a l i n t o n a t i o n c o n t o u r s a n d t h e i r d e v e l o p m e n t d u r i n g t h e f i r s t 40 year of l i f e i s r e l a t i v e l y sparse. C r y s t a l ' s (1973a) review discusses t h i s problem and notes that i n many instances the avai l a b l e information i s anecdotal, at best. Pike (1949) purports to have demonstrated that infants model t h e i r intonation patterns a f t e r the patterns employed by t h e i r parents. Pike and her husband avoided the use of the r i s i n g intonation contour ('baby talk') i n the presence of t h e i r daughter, Barbara, who was 'taught' to produce a f a l l i n g intonation contour on the words 'baby', 'Daddy', 'Mommy', and 'Judy'. The experiment was begun at the time Barbara was 'ready to learn to speak' (p. 22). Since no age i s mentioned, we might assume from the data given that the c h i l d was between nine and f i f t e e n months of age. At one point i n the experiment, the family had occasion to leave Barbara i n the care of neighbours for a period of four days. Because the neighbours were unaware of the experiment, they employed r i s i n g intonations i n t h e i r speech to Barbara, who i n turn began using them i n her own speech. When the parents returned and the experiment resumed, Barbara again employed f a l l i n g intonations i n her speech, although she frequently employed the r i s i n g intonation patterns as we l l . The sit u a t i o n s i n which the d i f f e r e n t patterns were employed were not sp e c i f i e d by the author. This anecdotal account would indicate that children are capable of mimicking p i t c h at a very early age and that those intonation patterns employed by the i n d i v i d u a l s having the most s o c i a l contact with the c h i l d w i l l be learned f i r s t . 41 Weir (1966) notes t h a t the u t t e r a n c e s o f young c h i l d r e n can be segmented i n t o ' s e n t e n c e - l i k e chunks, r e g a r d l e s s o f the i n t e l -l i g i b i l i t y of the u t t e r a n c e to an a d u l t l i s t e n e r 1 and hypothe-s i z e s t h a t i n t o n a t i o n p a t t e r n s are p e r c e i v e d and l e a r n e d e a r l y i n l i f e 'perhaps i n d e p e n d e n t l y of the segmental phonemes' (p. 153). Regarding the e f f e c t o f d i f f e r e n t l i n g u i s t i c environments on language a c q u i s i t i o n , Weir and Maccoby r e c o r d e d f o u r i n f a n t s : one Chinese, two A r a b i c and one American, between s i x and e i g h t months of age. They were a b l e to i d e n t i f y the Chinese i n f a n t on the b a s i s of ' d i s t i n c t p i t c h p a t t e r n s ' but c o u l d not d i s t i n g u i s h the A r a b i c babies from the American baby (p. 155). A f u r t h e r study i n v o l v i n g f i f t e e n b a b i e s ( f i v e C h i n e s e , f i v e Russian and f i v e American) was i n p r o g r e s s a t the time Weir's paper was p r e s e n t e d . P r e l i m i n a r y r e s u l t s i n d i c a t e d t h a t a t 6.5 months of age the Chinese s u b j e c t used a d i f f e r e n t s u p r a -segmental p a t t e r n from the Russian and American b a b i e s : whereas the Russian and American babies showed l i t t l e v a r i a t i o n i n p i t c h over i n d i v i d u a l s y l l a b l e s , the Chinese i n f a n t e x h i b i t e d much v a r i a t i o n over s i n g l e vowels. The p i t c h o f the Russian and American b a b i e s ' u t t e r a n c e s v a r i e d 'over a number of s y l l a b l e s ' (p. 156). In c o n t r a s t , Nakazima (1962, 1966) found no meaningful d i f f e r e n c e s i n the speech o f Japanese and American i n f a n t s b e f o r e the age of one y e a r . During the ' R e p e t i t i v e B a b b l i n g Stage' ( s i x to e i g h t months) the use of whispers and h i g h p i t c h was common, as were v a r i a t i o n s on a s i n g l e sounds. I m i t a t i o n 42 of parental intonation patterns occurred, but there was no p i t c h s h i f t as suggested by Lieberman (1967). Between nine months and one year conversation-like changes i n p i t c h and stress were noticeable. From about one year of age, differences i n intona-t i o n were observed between the Japanese and American in f a n t s . I t was contended that the prosodic system of the parents * speech was beginning to influence the i n f a n t s ' speech development. A cro s s - s e c t i o n a l study on the development of speech i n t o -nation i n the f i r s t two years of l i f e was c a r r i e d out by Tonkova-Yampol'skaya (1969) employing 170 subjects. Utterances were recorded on magnetic tape and analyzed using an intonograph. Each sound intonogram contained a sound oscillogram (with 2-msec time di v i s i o n s ) and tracings of fundamental frequency and inten-s i t y . Behavioural observations made during the data c o l l e c t i o n stage were used as an aid i n the i n t e r p r e t a t i o n of the r e s u l t s . Throughout the f i r s t month of l i f e , c r i e s indicated discomforts such as hunger, pain and wetness. In the second month, comfort and discomfort sounds could be distinguished. During the t h i r d month, sounds of happiness and laughter appeared. From t h i s time u n t i l the s i x t h month, voc a l i z a t i o n s indicated discontent, happi-ness, p l a c i d cooing and laughter. During the second h a l f year of l i f e , new expressional forms appeared, such as exclamatory del i g h t and. calm s a t i s f a c t i o n . Although a requesting form of intonation appeared at about seven.months, a questioning intona-t i o n did not appear u n t i l well into the second year. Since the intonograms of the infants revealed a gradual approximation to adult intonation patterns, i t was decided to 43 compare the infant intonation patterns obtained with those of adults. Four basic adult intonation pattern configurations were c l a s s i f i e d as follows: (1) fundamental frequency and i n t e n s i t y varying together and rhythmically: e.g., offense, remonstration, threat. (2) fundamental frequency r i s e s and then remains at a c e r t a i n l e v e l : i n t e n s i t y increases and then decreases; e.g., assertion, enumeration. (3) fundamental frequency r i s e s , f a l l s and then r i s e s again: i n t e n s i t y f a l l s , r i s e s and then f a l l s again; e.g., surprise, consternation, questioning. (4) fundamental frequency r i s e s sharply, f a l l s abruptly at the end of the sentence; e.g., command, persuasion, i n v i t a t i o n , request based on Tonkova-Yampol 1skaya (p. 131, 1969) Table II shows the i n f a n t intonation patterns and t h e i r adult counterparts. Insert Table II about here. Tonkova-Yampol'skaya claims that the newborn cry, at f i r s t lacking i n meaning, quickly acquires the meaning of discomfort. Fundamental frequency and i n t e n s i t y are i n i t i a l l y undifferen-t i a t e d . The intonation of discomfort i n the c h i l d f u l l y coincides with that of the adult. I t i s further suggested that 44 TABLE II INFANT INTONATION PATTERNS AND THEIR ADULT COUNTERPARTS Infant Intonation Pattern Age of Appearance Adult Counterpart i n d i f f e r e n t 2-7 months assertion / enumeration happiness, d i f f e r -entiated into exclamatory de-l i g h t and con-tented noises before 6 months aft e r 6 months consternation expressive calm cooing 7 months sharp increase i n occurrence at 9 months affi r m a t i o n requesting 7 months to end of 2nd year adult emotional request i n s i s t e n t 10 months occurrence i n -creases with age persuasion, i n s i s t e n t command questioning 2nd year questioning based on Tonkova-Yampol*skaya (1969, p. 133-135) 45 t h i s primary intonation structure may be of a b i o l o g i c a l nature. Adult speech i s characterized by d i f f e r e n t i a t i o n s of fundamental frequency and i n t e n s i t y . That t h i s d i f f e r e n t i a t i o n occurs i s taken as evidence for c o r t i c a l c ontrol of the speech apparatus. Furthermore, since the intonation patterns used by c h i l d r e n appear to be based on those of adults, one could i n f e r the 'establishment of conductive pathways between verbal-auditory and vocal-motor c o r t i c a l analyzers and speech organs' (p. 137). Wasz-Hockert et a l . (1968) c l a s s i f i e d t h e i r data into f i v e d i f f e r e n t intonation contours: r i s e - f a l l , f a l l , r i s e , l e v e l and f a l l - r i s e . Ah add i t i o n a l category c a l l e d 'no form' was added for c l a s s i f i c a t i o n of those c r i e s which were v o i c e l e s s , or contained g l o t t a l plosives or sounds of less than 4 00 msec duration. The intonation contours were defined.by a 'change i n the p i t c h l e v e l , when exceeding 10 percent of the p i t c h during more than 10 percent of the length of the cry' (p. 10). Table III shows the percentage of each type of contour which appeared for the d i f f e r -ent cry types. Insert Table III about here. I t should be evident that the studies mentioned above vary considerably with respect to age of the subjects and parameters examined. In the present study we hope to e i t h e r v e r i f y or re-fute the claims made by researchers i n previous studies 46 TABLE III PERCENT OCCURRENCE OF EACH INTONATION CONTOUR FOR BIRTH, PAIN, HUNGER AND PLEASURE SIGNALS Age 0 - 1 month 1.-7 months Cry type B i r t h Pain Hunger Pain Hunger Pleasure Contour RF 13 23 78 18 81 31 F 31 62 1 77 4 10 R 3 8 - 2 - 8 L 36 2 11 3 1 46 FR - - - - 6 No form 16 5 9 - 14 -based on Wasz-Hockert et a l . (1968, p. 40) 47 regarding fundamental frequency and duration. I t w i l l not be possible to d i r e c t l y compare our r e s u l t s for s p e c i f i c intonation contours with those of past studies, since we have not defined our contours i n the same manner as e i t h e r Tonkova-Yampol'skaya or Wasz-HOckert et a l . , for example; c f . Chapter Two. I t should, however, be possible to compare the r e s u l t s of our study with these l a t t e r studies i n a general fashion. 1.27. E x t r a l i n g u i s t i c factors i n language development 1.271. Conditioning studies There have been a number of studies concerned with the s o c i a l and non-social conditioning of i n f a n t v o c a l i z a t i o n s . Rheingold,. Gewirtz and Ross (1959) showed that vocal behaviour i n three-month-old, i n s t i t u t i o n a l i z e d infants could be condi-tioned by simultaneously smiling, clucking, and touching the infant's abdomen af t e r each v o c a l i z a t i o n . These three a c t i v i t i e s combined, acted as a r e i n f o r c i n g stimulus which very quickly raised the rate of v o c a l i z a t i o n above the baseline l e v e l . The disappearance of the r e i n f o r c i n g stimulus during e x t i n c t i o n caused the rate of v o c a l i z a t i o n to return to the baseline l e v e l . As a sequela to Rheingold's study, Weisberg (1963) demon-strated the e f f e c t s of contingent and non-contingent s o c i a l and non-social reinforcement on rates of v o c a l i z a t i o n i n three-month-old i n s t i t u t i o n a l i z e d i n f a n t s , whereby he c o n t r o l l e d for the presence of the experimenter (E). The r e s u l t i n g six experimental groups were: [ (1) No E present, (2) E present but expressionless, 48 (3) non-contingent s o c i a l stimulation, (4) non-contingent non-s o c i a l stimulation, (5) contingent s o c i a l stimulation, and (6) contingent non-social stimulation. A door chime served as the non-social r e i n f o r c i n g stimulus, whereas s o c i a l r e i n f o r c e -ment consisted of E rubbing the infant's chin, smiling and say-ing "yeah". Conditioning occurred i n the two groups which had undergone contingent reinforcement, with the s o c i a l l y reinforced group being the most vocal. Todd and Palmer (1968) reinforced i n f a n t v o c a l i z a t i o n s using a tape-recorded message. In one group, conditioning was ca r r i e d out with an adult present, while i n the other group no adult was present. Both groups showed s i g n i f i c a n t increases i n the rate of v o c a l i z a t i o n ; however, e x t i n c t i o n was more pronounced i n the 'adult present' group. Thus i t was demonstrated that although the presence of a human increases the effectiveness of vocal reinforcement, i t i s not a necessary p r e r e q u i s i t e . Con-trar y to the r e s u l t s of Todd and Palmer, Ramey and Ourth (1971). found no difference i n the rate of v o c a l i z a t i o n , whether or not the experimenter was present. They argue that since Todd and Palmer obtained baseline r e s u l t s with no experimenter present, ' i t was impossible to determine from t h e i r data i f the presence of an adult would, i n and of i t s e l f , tend to increase the rate of v o c a l i z a t i o n during the conditioning phase' (p. 296). Routh (1969) conducted a study involving both home-reared and i n s t i t u t i o n a l i z e d infants between the ages of two and seven months. Consonants and vowels were s e l e c t i v e l y reinforced using 49 the procedure of Rheingold et a l (1959) . The three groups — (1) consonants only reinforced, (2) vowels only reinforced, and (3) vowels and consonants reinforced — a l l showed an increase i n v o c a l i z a t i o n . More s i g n i f i c a n t l y , however, the groups which were s e l e c t i v e l y reinforced for a p a r t i c u l a r sound category showed an increase i n the production of the sounds i n the r e i n -forced category. Ramey and Ourth (1971) examined the e f f e c t of delay of reinforcement on rate of v o c a l i z a t i o n i n infants aged three months, s i x months and nine months. Infants were randomly assigned to one of three delay of reinforcement i n t e r v a l s : 0 sec, 3 sec, and 6 sec. Only the 'no delay' condition was ef-fe c t i v e i n producing an increase i n the rate of v o c a l i z a t i o n at a l l ages. There was no developmental trend i n the a b i l i t y of the infants to cope with a delay of reinforcement. Several people have attempted to determine the effectiveness of the various components of reinforcement employed i n these conditioning studies. In a study by Schwartz et al.(1970), v i -sual, t a c t i l e and auditory stimulation were examined separately, i n combinations of two, and a l l together. Although conditioning occurred, there were no s i g n i f i c a n t differences among the groups, i n d i c a t i n g that no one event was more r e i n f o r c i n g than another. Ramey and Watson (1970; c i t e d i n Ramey and Hieger, 1972) used ei t h e r a l i g h t alone or a l i g h t plus a one-kHz tone as r e i n f o r -cers of vocal behaviour i n ten- and sixteen-week-old i n f a n t s . At ten weeks, no change from the baseline occurred. At sixteen 50 w e e k s , t h e r e w a s a s i g n i f i c a n t i n c r e a s e i n m e a n v o c a l i z a t i o n w h i c h w a s f o u n d t o b e l a r g e l y a r e s u l t o f t h e m a l e s ' r e s p o n s e t o t h e l i g h t ; f e m a l e s w e r e n o t c o n d i t i o n e d i n e i t h e r c a s e . A s t u d y b y W a t s o n (1969) i n v o l v i n g a d i f f e r e n t m o d a l i t y , v i s i o n , i n d i c a t e d t h a t m a l e s c o n d i t i o n u n d e r v i s u a l r e i n f o r c e m e n t w h i l e f e m a l e s c o n d i t i o n u n d e r a u d i t o r y r e i n f o r c e m e n t . H u t t (1972) n o t e d t h a t , i n h e r e x p e r i e n c e , f e m a l e s u b j e c t s w e r e m o r e i n t e r e s t e d i n a u d i t o r y p a t t e r n s , w h i l e m a l e s w e r e m o r e i n t e r e s t e d i n v i s u a l p a t t e r n s . A l t h o u g h t h e r e a r e s o m e d i s c r e p a n c i e s ( s u c h a s e x i s t s b e t w e e n t h e S c h w a r t z e t a l . s t u d y a n d R a m e y a n d H i e g e r ' s s t u d y ) a m o n g t h e s t u d i e s m e n t i o n e d , t h e r e a r e a l s o s o m e i n t e r -e s t i n g c o n s i s t e n c i e s ( s u c h a s t h e m a l e s ' r e s p o n s e t o v i s u a l s t i m u l i n o t e d a b o v e ) . I t w o u l d b e o f i n t e r e s t t o d e t e r m i n e w h e t h e r a n y o f t h e s e f i n d i n g s w o u l d b e b o r n e o u t i n t h e c h i l d ' s p r e f e r e n c e f o r c e r t a i n t o y s . F o r e x a m p l e , i f f e m a l e s a r e m o r e i n t e r e s t e d i n a u d i t o r y p a t t e r n s , p e r h a p s t h e y w o u l d p r e f e r t o p l a y m o r e w i t h n o i s e m a k e r s , s u c h a s r a t t l e s o r s q u e a k e r s . M a l e s , b e i n g m o r e v i s u a l l y o r i e n t e d , m a y s h o w a p r e f e r e n c e f o r t o y s w h i c h a r e v i s u a l l y s t i m u l a t i n g , s u c h a s m o b i l e s . A t t e m p t s h a v e b e e n m a d e t o d e t e r m i n e w h e t h e r m a l e o r f e m a l e v o i c e s a r e d i f f e r e n t i a l l y r e i n f o r c i n g f o r y o u n g i n f a n t s . B a n i k i o t e s e t a l . (1972) f o u n d n o s i g n i f i c a n t . d i f f e r e n c e i n e i t h e r n u m b e r o r f u n d a m e n t a l f r e q u e n c y o f v o c a l i z a t i o n s , b e t w e e n v o c a l i z a t i o n s t h a t w e r e r e i n f o r c e d b y a t a p e d m a l e v o i c e a n d v o c a l i z a t i o n s t h a t w e r e r e i n f o r c e d b y a t a p e d f e m a l e v o i c e . A n i n s p e c t i o n o f s u p p r e s s i o n o f i n f a n t v o c a l i z a t i o n s a s a f u n c t i o n 51 of parental voice s e l e c t i o n revealed that the preferred voice brought about a greater suppression of v o c a l i z a t i o n than d i d the non-preferred voice (Barrett-Goldfarb and Whitehurst, 1973). There were no s i g n i f i c a n t differences i n the s e l e c t i o n of the father's or the mother's voice, except i n one subject who chose the father's voice i n twelve out of f i f t e e n sessions. The sub-jects i n t h i s study were one year of age. 1.272. Parent-infant studies Jones and Moss (19 71) state that at two weeks the amount of infa n t v o c a l i z a t i o n i s p o s i t i v e l y r e l a t e d to the amount of maternal speech, whereas at three months i t i s p o s i t i v e l y related to the amount of maternal speech following the v o c a l i z a t i o n s . This r e l a t i o n s h i p i s also dependent on the infant's state. There was an increase i n the amount of v o c a l i z a t i o n with age, with more voc a l i z a t i o n s occurring when the i n f a n t was i n an active state: i f the i n f a n t was i n an active state, he/she vocalized more alone than i n the presence of the mother. These findings are s i m i l a r to those of Nakazima (1962, 1966), who also found that his sub-ject s tended to vocalize more when they were alone. Jones and Moss (1971) suggest that the change i n the r e l a -tionship between infant and maternal v o c a l i z a t i o n s that occurs from two weeks to three months may be rela t e d to the increase i n frequency of v o c a l i z a t i o n with age (p. 1029). At two weeks, the infa n t vocalizes r e l a t i v e l y . i n f r e q u e n t l y . The occurrence of v o c a l i z a t i o n i s novel, and the mother responds v o c a l l y . The 52 infant may vocalize more i n order to e l i c i t more responses from the mother. By three months, the novelty e f f e c t has abated. Further, both the infant and the mother may e l i c i t vocal respon-ses from each other by the use of non-vocal, as well as vocal s t i m u l i . Bateson (1971) observed that mother and i n f a n t t y p i c a l l y vocalize by turns: the mother vocalizes and waits fo r her i n f a n t to respond before v o c a l i z i n g again. The r e s u l t s of Jones and Moss (1971) seem to indicate that t h i s type of conversational s i t u a t i o n occurs at three months of age, when the degree of s o c i a l i z a t i o n between mother and infant has increased. The l o c a t i o n of the infant i n the home environment has been shown to have a s i g n i f i c a n t e f f e c t on the amount of v o c a l i z a t i o n (Lewis and Freedle, 1973). Vocalizations occurred most often when the i n f a n t was free of physical r e s t r a i n t (e.g., i n the playpen, on the f l o o r , or i n an infant seat). Fewer v o c a l i z a -tions occurred when the infants were on t h e i r mothers' laps, i n t h e i r c r i b s , on changing tables, or i n the bathtub. The mothers' r e l a t i v e v o c a l i z a t i o n s were greatest when the i n f a n t was on the f l o o r , on the changing table, i n the bathtub, or on the sofa, and least when the infant was i n the playpen, c r i b or jumper. I t i s worth noting that while the mother vocalized l e a s t when the infant was i n the playpen, the infant vocalized most i n that l o -cation. This s i t u a t i o n i s non-social and conforms with the findings of Jones and Moss (1971) and Nakazima (1962) , whose subjects tended to vocalize more i n s i m i l a r non-social situations. 53 The q u a l i t y of maternal care i s another s i g n i f i c a n t variable i n the c h i l d ' s development. Beckwith (1971) found that infants whose mothers r e s t r i c t e d environmental exploration and gave le s s verbal and physical contact, scored lower on the C a t t e l l Scale and Motor Gesell Scale than infants who were given much verbal and physical contact and freedom to explore. Those infants who had more s o c i a l contact with people other than t h e i r parents tended to have higher scores on the C a t t e l l Scale. The a l e r t and s e n s i t i v e mother tends to have the more re-sponsive baby and vice-versa (Osofsky and Danzger, 1974). These researchers found consistencies i n i n f a n t state and behavioural measures across s i t u a t i o n s . Similar r e s u l t s were obtained by Eckerman and Rheingold (1974). A comparison of the responses of ten-month-old infants to a passive person and to a responsive person revealed that the l a t t e r was p h y s i c a l l y contacted by the i n f a n t more frequently. Moss (1967), who observed the i n t e r a c t i o n of mother and f i r s t - b o r n i n f a n t over the f i r s t three months of l i f e , remarks that the 'state of the infant a f f e c t s the quantity and q u a l i t y of maternal behavior 1 (p. 34). As the i n f a n t matured, there tended to be a decrease i n feeding behaviour and close physical contact and an increase i n attending and a f f e c t i o n a t e behaviour on the part of the mother. A number of sex differences were noted i n both the infant and maternal variables studied, but when contr o l was made for the state of the i n f a n t , most of the d i f f e r -ences were no longer s i g n i f i c a n t . Moss notes that infant's 54 cry seemed to determine the mother's behaviour. There was a r e l a t i v e i n s t a b i l i t y i n the mother-infant system over the three-month period which was thought to r e f l e c t the uncertainty of mothers of f i r s t - b o r n c h i l d r e n . With time, the mother's c o n f i -dence increased as she became more f a m i l i a r with her i n f a n t and attachment behaviours began to develop. C r o s s - c u l t u r a l studies of caretaking s t y l e s have borne out some i n t e r e s t i n g claims with respect to language development. C a u d i l l (1972) compared the caretaking behaviours of Japanese and American mothers, the l a t t e r of whom responded more quickly to t h e i r babies, i r r e s p e c t i v e of the type of v o c a l i z a t i o n , and encouraged a c t i v i t y and vocal responsiveness i n t h e i r babies. Consequently, the American babies uttered many more 'happy' sounds than did the Japanese babies. Japanese mothers, on the other hand, were more concerned with soothing and quieting t h e i r babies; they tended to view t h e i r babies as an extension of them-selves and placed more importance on physical contact and less importance on v o c a l i z a t i o n than did the American mothers, who tended to view t h e i r infants as p o t e n t i a l l y independent beings. Although the role of the mother i n the vocal development of the infant has gathered a considerable amount of attention, the ro l e of the father has been neglected. In a study of , infants up to three months of age, Rebelsky and Hanks (19 71) found that the average father spent 37.7 seconds per day i n contact with his i n f a n t . During t h i s time, a mean of 2.7 vocal i n t e r a c t i o n s took place. Although large i n d i v i d u a l differences were observed, even 55 the father with the most interactions spent only about 10.5 minutes per day with his c h i l d . Just over one-half of these interactions occurred during caretaking a c t i v i t i e s . In view of the r e s u l t s of Rebelsky and Hanks (1971) , i t does not seem surprising that the father has been ignored, given his minimal r o l e i n the c h i l d ' s early l i f e . However, an observation made by Friedlander et a l . (1972) cautions against overlooking the father's role no matter how minimal i t may seem. In a study of' infants' natural language environment i n the home, i t was noted that one female subject ultimately learned Spanish as a r e s u l t of her father's speaking only Spanish i n her presence; the sub-je c t ' s mother spoke to her i n English. The language environment of t h i s family had been sampled from 7 AM to 9 PM every day for a week, r e s u l t i n g i n a 3-hour recording. The c h i l d ' s exposure to her father accounted for only f i v e percent (351 sec) of the t o t a l language l i s t e n i n g opportunities. In terms of d i r e c t address, the c h i l d was exposed to her mother 59 percent of the time and her father only 37 percent of the time. No figures are reported for the actual length of time that the c h i l d was d i r e c t l y addressed by her father, but we do know that i t could only be a portion of the 351 seconds o v e r a l l exposure to the father's speech. We must also assume that the sample obtained was t r u l y representative of the c h i l d ' s exposure to her father's speech. In spite of the comparatively small amount of time that the c h i l d was exposed to her father, she had developed a grasp of Spanish by one year of age. In an informal follow-up session six months l a t e r , the c h i l d was able to name objects, follow 56 simple d i r e c t i o n s , answer questions and could carry on a simple conversation i n Spanish. Observations such as Friedlander's cause one to question the emphasis on mother-infant i n t e r a c t i o n i n c h i l d language a c q u i s i -t i o n research. I t i s apparent that for Friedlander's subject, the minimal exposure to the father was very important. In many fa m i l i e s , the father i s away from home during the c h i l d ' s waking hours. His presence therefore becomes novel to the c h i l d . In t h i s event, the c h i l d may be more attentive to his/her father during the l i m i t e d time that the father i s a v a i l a b l e for i n t e r -action. This explanation i s i l l u s t r a t i v e of the 'discrepancy p r i n c i p l e ' discussed by Kagan (1971) whereby: '...an event that i s moderately discrepant from the one that generated a schema (e.g., a l t e r a t i o n s i n the temporal and s p a t i a l configuration of the o r i g i n a l stimu-lus) w i l l e l i c i t longer f i x a t i o n s than mini-mally discrepant events or events that bear no r e l a t i o n to the schema. A c u r v i l i n e a r r e l a t i o n i s hypothesized between f i x a t i o n time, on the one hand, and degree of discrep-ancy between the perception of an encountered event and the schema for the o r i g i n a l event, on the other...' (p. 62) The father i n Friedlander's study could be equated to a d i s -crepant stimulus. The discrepancy p r i n c i p l e may account for f i x a t i o n time on the part of the i n f a n t but i t does not explain the quantity or q u a l i t y of learning that occurs while the i n f a n t i s attending to the stimulus. This would be valuable information 57 i n terms of language a c q u i s i t i o n as well as other forms of cogni-t i v e development. This section has attempted to describe some of the s a l i e n t e x t r a l i n g u i s t i c factors which are thought to influence language development. I t i s contended that some of these factors such as type of object (e.g. v i s u a l or auditory), or whether an object i s novel to the c h i l d , may be of importance i n the ultimate explanation of the r e s u l t s of t h i s study. Although the aspects of parent-child i n t e r a c t i o n are not being s p e c i f i c a l l y examined here, they may influence some of the r e s u l t s of t h i s study and w i l l be discussed as deemed appropriate. 58 1.3. Summary and statement of the problem The l i t e r a t u r e regarding the so- c a l l e d p r e l i n g u i s t i c stage of development includes a number of studies concerning the devel-ft opment of the c h i l d ' s phonemic system. Since we are primarily concerned with suprasegmental development, these studies were not discussed i n t h i s review. In contrast, information regarding the development of intonation and the influence of the c h i l d ' s ecosystem on t h i s development i s scarce and i n many cases anec-d o t a l . Studies of the crying behaviour of infants have shown that these l a t t e r areas deserve exploration, since many of the findings could be of value i n diagnostic procedures, as well as providing additional information on language a c q u i s i t i o n and the development of communicative competence i n general. Linguists have t r a d i t i o n a l l y applied the adult terms 'phoneme*, ' s y l l a b l e ' and 'word1 to infant utterances, even r though these terms have l i t t l e relevance to inf a n t speech (Cr y s t a l , 1973b). A concern with the a r t i c u l a t o r y correlates of speech has led many students of c h i l d language to ignore any developmental trends occurring i n the realm of intonation and meaning. The tendency to dismiss the whole f i r s t year as the ' p r e l i n g u i s t i c ' stage has meant that many important milestones i n language development may have gone unrecognized. We have yet to adequately explain why, by the end of the f i r s t year, the in f a n t appears to have mastered many of the prosodic nuances of his/her language. Furthermore, many questions with regard to semantic development i n the f i r s t year remain unanswered. 59 The process of vocal d i f f e r e n t i a t i o n i n the infant has been described by several researchers, notably Lewis (1951) and Wolff (1969), but only i n r e l a t i o n to i n t e r n a l states such as hunger, pain and pleasure. Instances of d i f f e r e n t i a l v o c a l i z a t i o n i n response to objects and people have been mentioned i n the l i t e r -ature, but no systematic studies of the phenomenon have been made. The intent of the present study i s to examine the c e r t a i n aspects of vocal d i f f e r e n t i a t i o n i n the infant's response to objects i n his/her environment. For the purposes of t h i s t h e s i s , the term 'vocal d i f f e r e n t i a t i o n ' i s defined to be the develop-mental process by which the i n f a n t comes to represent d i f f e r e n t states or events by d i f f e r e n t types of utterances; ' d i f f e r e n t i a l v o c a l i z a t i o n ' , on the other hand, i s defined to be an act which occurs when the infant's vocal output d i f f e r s s i g n i f i c a n t l y from one s i t u a t i o n to another. The goal of t h i s thesis i s to determine i f the infant modi-f i e s his/her vocal output i n any way, i n response to an object. The context of subject v o c a l i z i n g alone (S) w i l l be used as a baseline or control condition i n order to determine i f there are s i g n i f i c a n t differences i n the subject plus object condition (SO). I f d i f f e r e n t i a l v o c a l i z a t i o n occurs, then the next step i s to examine i t s change over time, which may be due to the influence of developmental' f a c t o r s . In the examination of the infant's response to objects, i t w i l l also be determined whether or not the infant's vocal r e-sponse varies from object to object, and, i f t h i s i s the case, 60 whether such d i f f e r e n t i a t i o n can be demonstrated over time. The contrasts of the d i f f e r e n t s i t u a t i o n a l contexts w i l l be c a r r i e d out by comparing intonation contours that occur i n the d i f f e r e n t contexts. The duration and within-utterance range of fundamental frequency w i l l also be taken into account i n the comparisons. An attempt to assess any developmental changes that may be occurring with respect to the variables mentioned above w i l l be made using chronological age, i n addition to mental and motor scores (as measured by the Bayley Scales of Infant Development), as covariates. CHAPTER 2 Method 2.1. Experimental design The present i n v e s t i g a t i o n i s based on a larger study of the development of speech sound production i n the infant and the ontogenesis of the sound-meaning c o r r e l a t i o n . In the larger study, nineteen infants (twelve males and seven females) served as subjects. A l l were normal, ' f i r s t - b o r n ' , f u l l - t e r m infants who were referred to E by l o c a l physicians. One of the infants had an older, adopted s i b l i n g . In the main study, E v i s i t e d each i n f a n t i n i t s home, be-ginning at the age of f i v e weeks and proceeding on a biweekly basis u n t i l the infant reached approximately one year of age. At each v i s i t , a fifteen-minute tape recording was made of the infant's v o c a l i z a t i o n s . In order to provide a measure of each infant's developmental status, the Bayley Scales of Infant Development (1969) were administered every three months, be-ginning at the age of three months. Each infant's home environ-ment was evaluated at four-month i n t e r v a l s using the Heimler Scale of So c i a l Functioning (Rev. I I , 1967); the f i r s t i n t h i s series of tests was administered around the time of the c h i l d ' s b i r t h . In addition, the parents kept records on t h e i r c h i l d ' s health status and development. The v o c a l i z a t i o n data included the infant's spontaneous utterances, as well as i n t e r a c t i v e sequences with adults or 61 62 objects. In the analysis, every utterance was categorized according to the s i t u a t i o n i n which i t occurred; i . e . , i n f a n t alone; i n f a n t v o c a l i z i n g to mother, father, adult female, adult male; and inf a n t v o c a l i z i n g i n the context of an object. Utter-ances were sampled from each of these categories and subjected to both perceptual and instrumental analyses. Two of the s i t u a t i o n a l categories mentioned above are exam-ined i n the present study: i n f a n t alone (S), and inf a n t vocal-i z i n g i n the context of various objects (SO). The context of infant alone served, for comparative purposes, as a pseudo-base-l i n e condition. The utterances produced i n the context of ob-jects were contrasted with each other and with those utterances produced i n the inf a n t alone condition. The contrasts were carri e d out using a computerized multivariate analysis program, i n which the variables of fundamental frequency of beginning-(BEGIN), middle- (MP), and end-points (END), duration (DUR), within-utterance range (RANGE) and contour were examined simul-taneously. The e f f e c t of each variable could be determined, as well as the combined e f f e c t s of the d i f f e r e n t v a r i a b l e s . Con-t r a s t s were examined for each subject both within and across age l e v e l s . In order to resolve some of the a n a l y t i c problems encoun-tered with small sample size the SO-data was recoded into four major categories, the c h a r a c t e r i s t i c s of which would appear to correspond with the sensory modalities by which the objects would be pri m a r i l y , or at lea s t most l i k e l y , apprehended: 63 V i s u a l (mobiles, tape recorder, microphone, p i c t u r e s , r e f l e c t i o n s , e t c . ) , Auditory + V i s u a l (music box, radio, e t c . ) , T a c t i l e + V i s u a l (stuffed toys, blankets, blocks, e t c . ) , and Auditory + T a c t i l e + V i s u a l ( r a t t l e s , b e l l s , 'squeaky' toys, e t c . ) . A technique known as Multiple C l a s s i f i c a t i o n Analysis (MCA; c f . Andrews et a l , 1967) was used to determine whether there was any difference among the object groups themselves, or between the S_ and various SO groups, across a l l v a r i a b l e s . The MCA program was also used to examine developmental trends with respect to the v a r i a b l e s . Each v a r i a b l e was con-sidered with respect to three separate measures of development: chronological age, Bayley Mental Score, and Bayley Motor Score. Intersubject differences were also examined v i a MCA. In addition, the d i s t r i b u t i o n s of the various contexts and contours were determined, as well as the development of the intonation contours over time. The vocalizations of eighteen subjects were examined i n t h i s study. Subject 108-M from the larger study was rejected because i t was thought that the c l a s s i f i c a t i o n of h i s utterances with respect to context was u n r e l i a b l e ; i n addition, t h i s subject was unavailable for an interim 6-month period and therefore his data are l o n g i t u d i n a l l y incomplete. He constantly kicked at a r a t t l e which was suspended over his c r i b . The tapes of these sessions amount to r a t t l e noise interspersed with v o c a l i z a t i o n s . According to the c r i t e r i a established f o r the c l a s s i f i c a t i o n of utterances with respect to context, a l l of the utterances from 64 these tapes should be classed as i n f a n t i n the context of an ob-j e c t (SO). In f a c t , many of the utterances were classed as vo-c a l i z a t i o n s i n the context of a r a t t l e even when there were other toys present i n the c r i b . There were also a number of utterances i n the SO category which should have been classed i n the S cate-gory had the r a t t l e noise not occurred. Two of the eighteen subjects i n t h i s study: 114-M and 201-M, exhibited no utterances i n the SO category. Of the s i x -teen subjects who did have utterances i n the SO category, the number of utterances varied, as did the number of d i f f e r e n t ob-j e c t s . Therefore, some subjects may have only vocalized i n the context of two d i f f e r e n t objects, while other subjects had as many as eleven d i f f e r e n t objects i n the SO category. 2.2. Subjects 2.21. Sex and age range The subjects for t h i s study were nineteen in f a n t s , reduced to eighteen -- eleven males and seven females — by the exclusion of 108-M for reasons discussed e a r l i e r . The v o c a l i z a t i o n s of ten subjects (101-F through 111-M), four females and six males, were analyzed between 5 weeks and 52 weeks. The remainder of the sub-ject s (112-M through 201-M) were studied from 5 weeks to between 24 and,26 weeks. Of the eighteen subjects, two exhibited no vo-c a l i z a t i o n s to objects, as mentioned e a r l i e r . The data of these two infants w i l l therefore be examined only with respect to the subject alone (S) condition. 65 2.22. Medical h i s t o r y The mothers of the infants were referred to E by l o c a l physicians on the basis of uneventful pregnancy, and no family h i s t o r y of gross physical or psychological disorders. A l l but three of the mothers had had no previous pregnancies. One i n -fant had an older adopted s i b l i n g . The infants were a l l judged to be normal, healthy babies at b i r t h . The average Apgar score was 8 (range 6 to 10). The, Apgar score i s a rat i n g system used to determine the immediate post-partum status of the i n f a n t . At one minute a f t e r b i r t h , the following signs are rated on a scale of 0 (unfavorable) to 2 (favorable): heart rate, r e s p i r a t o r y e f f o r t , muscle tone, re-f l e x i r r i t a b i l i t y and color. The maximum score obtainable i s 10. Generally, a score between 8 and 10 indicates a healthy post-partum status. Ongoing medical and parental reports throughout the study indicated that the majority of the children remained normal and healthy. Exceptions were 107-M, 114-M and 115-F who had ongoing medical problems, and 101-F, 103-M, 104-F, 111-M, 112-M, 113-M and 201-M who had tr a n s i t o r y health problems such as measles, f l u and b r o n c h i o l i t i s . 2.23. Home environment and biographical information on the  families 2.231. Language, education, occupation and income The parents of the children i n t h i s study were native speakers of English and were representative of the l o c a l 66 population i n terms of education, occupation and accomodation (see Table IV), as well as income, r e l i g i o n and i n t e r e s t s . Insert Table IV about here. The average income (1970) of the f a m i l i e s was $11,500. This figure was calculated on the basis of sixteen f a m i l i e s since three of the families had incomes which were not t y p i c a l of the o v e r a l l sample. The incomes of these f a m i l i e s were: $2,600, $27,000 and $65,000. During the course of the study, two fathers changed jobs, and two of the fathers who had been students obtained f u l l - t i m e jobs. Table IV indicates each mother's occupation before the b i r t h of the c h i l d . Only seven of the mothers returned to work a f t e r the b i r t h of t h e i r c h i l d . Of these, one (117-M's mother) returned immediately, while the remaining six (from the families of 101-F, 102-F, 103-M, 106-F, 112-M and 116-F) did not return to work u n t i l t h e i r babies were si x months of age or older. The mother of 106-F was the only one of these six mothers who worked f u l l - t i m e ; the others worked only sporadically or part-time at the most. 2.232. Heimler 'Scale r e s u l t s As mentioned e a r l i e r , the Heimler Scale of S o c i a l Function-ing (Rev. II) was administered at i n t e r v a l s throughout the study. This scale gives an index of an i n d i v i d u a l ' s subjective view of 67 TABLE I V PARENTAL BIOGRAPHICAL INFORMATION SUBJECT ID PARENT AGE E D U C A T I O N ( y r s ) s e c / v o c / i i n i v OCCUPATION ACCOMMODATION 1 0 1 - F M o t h e r 2 5 3 / 2 / 0 p r a c t i c a l n u r s e 1 B.R. a p t . F a t h e r 3 3 3 . 5 / 4 / 0 t o o l a n d d i e m a k e r * 1 0 2 - F M o t h e r 2 3 5 / 1 / 0 d e p a r t m e n t a l s t o r e manager 3 room b a s e -ment s u i t e F a t h e r 2 4 6 / 0 / 1 i n s u r a n c e i n s p e c t o r 1 0 3 - M M o t h e r 2 7 4 / 0 / 0 s e c r e t a r y h o u s e F a t h e r 2 9 5 / 1 . 5 / 0 w a r e h o u s e m a n 1 0 4 - F M o t h e r 2 4 4 / 0 / 1 s e c r e t a r y 2 B.R. a p t . F a t h e r 2 4 4 / 0 / 7 s t u d e n t 1 0 5 - M M o t h e r F a t h e r 2 8 2 7 2 / 1 / 0 4 / 3 / 0 s e c r e t a r y f i r e m a n 1 B.R. a p t . ( 1 2 ) c o n d o m i n i u m (2 4 ) h o u s e 1 0 6 - F M o t h e r 2 8 4 / 0 / 3 t e a c h e r 3 B.R. h o u s e F a t h e r 3 0 4 / 1 / 4 s a l e s s p e c i a l i s t 1 0 7 - M M o t h e r 2 4 4 / 2 / 0 s e c r e t a r y s u i t e ( 2 8 ) -F a t h e r 2 3 3 . 5 / 0 / 0 b a n d s a w o p e r a t o r h o u s e 1 0 8 - M M o t h e r 2 5 4 / 1 / 0 n u r s i n g a s s i s t a n t 2 B.R. a p t . F a t h e r 2 5 4 / 0 / 3 c h a r t e r e d a c c o u n t a n t 1 0 9 - M M o t h e r 2 3 4 / 0 / 3 s a l e s c l e r k 2 B.R. a p t . F a t h e r 2 4 4 / 0 / 5 b u y e r 68 TABLE IV (continued) SUBJECT ID u PARENT AGE EDUCATION(yrs) sec/voc/univ OCCUPATION ACCOMMODATION 110-M Mother 26 5/0/1 teacher house(24) Father 26 4/0/4 forest e r house 111-M Mother 32 4/5/0 nurse condominium Father 34 4/2/0 carpenter 112-M Mother 28 4/3*/0 secretary house Father 29 5/5*/0 engineer 113-M Mother 21 4/0/1 housewife apartment Father 29 5/0/3 student 114-M Mother 28 4/3/1 nurse house Father 31 4/1/0 foreman 115-F Mother 22 4/0/3 teacher house Father 23 4/0/4 Junior Administrator 116-F Mother Father 20 21 4/0/0 4/0/0 f i l e c l e r k machine operator apt.(11X house 117-M Mother 32 4/0/7 lawyer apt.(44) Father 46 4/0/8 doctor apt. 118-F Mother 27 2/0/0 cler k house Father 31 2/3/0 o f f i c e machine engineer 201-M Mother 28 4/0/0 housewife house Father 35 4/0/3 l insurance ( c l e r i c a l ) A l l information regarding age and occupation was c o l l e c t e d at the beginning of the study, before the b i r t h of the baby. ( ) refer s to moves made during the course of the study; the num-ber i n parentheses indicates the approximate age of the baby i n weeks at the time of the move. * = part-time schooling. 69 t h e s a t i s f a c t i o n s and f r u s t r a t i o n s w i t h i n h i s / h e r l i f e . I t i n d i c a t e s how p o s i t i v e l y t h e s i t u a t i o n s o f work, f i n a n c e s , mar-r i a g e , f a m i l y l i f e , and f r i e n d s h i p s a r e v i e w e d . I t a l s o r e v e a l s t h e degree t o w h i c h a c t i v i t y i s i n h i b i t e d by f a t i g u e o r d e p r e s -s i o n ; what escape r o u t e s , i f any, a r e r e l i e d on ( d r u g s , a c t i n g -o u t b e h a v i o u r , e t c . ) ; and how e f f e c t i v e t h e p e r s o n f e e l s him-s e l f / h e r s e l f t o be w i t h i n h i s / h e r e n v i r o n m e n t . I n our s t u d y , a l l s c o r e s ( w i t h 4 i n d i v i d u a l e x c e p t i o n s ) were h i g h as e x p e c t e d from e s s e n t i a l l y s t a b l e m i d d l e - c l a s s f a m i l i e s . The d a t a on each p a r e n t u s u a l l y c o n s i s t e d o f 4 H e i m l e r s c h e d u l e s a d m i n i s t e r e d a t i n t e r v a l s o f a p p r o x i m a t e l y 4 months. The f i r s t was most u s u a l l y done p r e - n a t a l l y , and on r a r e o c c a -s i o n s s h o r t l y a f t e r the b i r t h o f t h e baby. Two t r e n d s appeared i n t h e d a t a . The m a j o r i t y o f t h e f a t h e r s d e m o n s t r a t e d more p o s i t i v e p e r c e p t i o n s o f t h e i r l i v e s a t t h e end o f t h e f i r s t y e a r t h a n a t t h e i n i t i a l i n t e r v i e w ( e i t h e r p r e - o r p o s t - n a t a l ) . The m a j o r i t y o f t h e mo t h e r s , on t h e o t h e r hand, showed h i g h e r p o s i t i v e s a t t h e f i r s t i n t e r v i e w and l o w e r s c o r e s a t t h e end o f t h e f i r s t y e a r . F u l l - y e a r s c o r e s f o r f a t h e r s t h a t c o u l d be c h a r a c t e r i z e d as r i s i n g i n p o s i t i v e o u t l o o k o r m a i n t a i n i n g a h i g h i n i t i a l l e v e l o c c u r r e d i n 9 c a s e s . I n 3 c a s e s t h e r e was a s t e a d y de-c r e a s e o f p o s i t i v e assessment o f l i f e s i t u a t i o n . There were f l u c t u a t i o n s w i t h i n t h e r e m a i n i n g s e r i e s o f s c o r e s . S i x o f t h e s e showed t h e t r e n d o f low f i r s t s c o r e and h i g h f i n a l r e p o r t , two remainded l e v e l , and one showed a drop i n p e r c e i v e d 70 p o s i t i v e s during the course of the year. None of the mothers maintained an o v e r a l l l e v e l score for the series of schedules. Six showed consistent decline i n scores, while only two increased c o n s i s t e n t l y . The remaining 11 mothers exhibited f l u c t u a t i n g scores for the se r i e s ; 7 of these ended with lower scores than on the f i r s t schedule. There were only four schedules i n the ent i r e body of data which evinced a ' c r i s i s ' situation'(these represent 2 fathers and 2 mothers); continuing contact with the four families dem-onstrated the passing nature of the d i f f i c u l t i e s i n a l l but one case. One mother was very depressed for several months due to a combination of anaemia, probably post-partum depression, and a very tenuous f i n a n c i a l s i t u a t i o n . She showed marked improve-ment by the end of the f i r s t year. None of the c r i s e s were severe enough to warrant professional intervention other than the routine services of the family physician. 2.233. Household organization The majority of the households i n the study were organized along conventional l i n e s . The husband was responsible for sup-porting the family f i n a n c i a l l y , while the wife attended to household tasks and cared for the baby. The degree of involve-ment of the father i n household a c t i v i t i e s varied with each family. S l i g h t l y more than h a l f of the fathers took an active part i n caring for the baby. With the exception of 117-M, whose mother worked, the children were r a r e l y l e f t with caretakers 71 other than members of the extended family (e.g. grandparents). Although 201-M was the only c h i l d who had a s i b l i n g , 107-M's five-year-old aunt stayed with that family from the time that the baby was about four months old u n t i l the end of the study. Pets kept i n four households (107-M, 112-M, 115-F and 201-M) were occasionally present during the taping sessions. The major o r i e n t a t i o n i n most of the homes was toward family- and social-centered a c t i v i t i e s . Only the family of 107-M tended to be child-centered. In two f a m i l i e s (111-M and 117-M), business a c t i v i t i e s played a dominant r o l e . The fathers of 103-M and 104-F were both students, and thus much of those f a m i l i e s ' l i v e s revolved around the fathers' schoolwork. The father of 104-F joined the work force about midway through the study, thus changing the o r i e n t a t i o n of that family. 2.234. Maternal care The mothers were generally consistent i n the way that they cared for t h e i r infants but there were exceptions. The mother of 101-F was anxious and would lose patience with the baby. This s i t u a t i o n improved a f t e r the c h i l d was about f i v e months old. The mother of 113-M had some problems i n deciding how to handle her baby. Table V shows each mother's preferred mode of stimulation of the c h i l d (cf. Clarke-Stewart, 1973) , as t h i s may have some bearing on the c h i l d ' s involvement or lack of involve-ment with objects i n i t s environment. This information i s based on observations of the mother-child i n t e r a c t i o n over the e n t i r e 72 study as well as maternal utterance counts. Where no strong preference f o r one mode was evident, the two most predominant methods of stimulation are noted. Insert Table V about here. Most of the infants were free to explore t h e i r environ-ments. There was a general concern on behalf of the mothers that t h e i r c h i l d r e n would not be involved i n s i t u a t i o n s that might cause bodily injury, but only the mother of 113-M tended to be over-protective of her c h i l d . Only 106-F was p h y s i c a l l y r e s t r i c t e d to her playpen i n the l i v i n g room, and l a t e r to the kitchen or recreation room. Portions of 107-M's home were blocked o f f . Most of the children had an abundance of stimulating play-things, both purchased and homemade. The mothers varied i n t h e i r a b i l i t i e s to use objects i n the environment to advantage: some were very creative while others were not. They also varied i n t h e i r understanding of t h e i r own c h i l d ' s functioning and t h e i r a b i l i t y to determine what a c t i v i t i e s would be stimu-l a t i n g for the c h i l d . i TABLE V MOTHERS1 PREFERRED MODES OF STIMULATION SUBJECT MODE ID 101-F material 102-F verbal 103-M verbal/physical 104-F verbal/material 105-M material/verbal 106-F material/verbal 107-M verbal 108-M physical/material 109-M material 110-M physical/material 111-M physical/material 112-M verbal 113-M physical 114-M verbal/material 115-F verbal/material 116-F material 117-M verbal 118-F physical/verbal 210-M verbal/physical 74 2.3. Procedure 2.31. Data c o l l e c t i o n 2.311. Instrumentation A Nagra IV-D portable tape recorder, AKG D202E d i r e c t i o n a l microphone and Ampex 434 low-noise tape were used i n the c o l -l e c t i o n of data. The tape recorder was c a l i b r a t e d to give a f l a t response (± 2 dB) over a frequency range of 50-10,000 Hz. Every attempt was made to place the microphone approximately 36" from the infant's mouth throughout recording sessions. 2.312. Taping s i t u a t i o n The biweekly recordings were made i n the in f a n t s ' homes. Every e f f o r t was made to preserve the natural home s e t t i n g . Any alt e r a t i o n s made were only for the purpose of reducing noise which would i n t e r f e r e i n the anal y s i s . Where there was heavy t r a f f i c outside the infant's home, recording was c a r r i e d out i n the quietest room. Radios, TVs and noisy appliances were turned o f f . In order to obtain as much v o c a l i z a t i o n data as possible, each mother was consulted as to the times during the day when her infant was most active. Every attempt was made to schedule recording sessions during these active periods. E f f o r t s were made to carry out recording sessions when both parents were at home; however, as most childrens' active periods occurred when the father was out of the home, the mother was usually the only parent present during recordings. Although E and the tape 75 recorder remained out of sight i n many of the sessions, E did occasionally i n t e r a c t with the i n f a n t s . The goal of each taping session was to obtain a f i f t e e n -minute recording of the infant's v o c a l i z a t i o n s under various conditions. The tape recorder was turned o f f i f the infant en-gaged i n inappropriate vocal behaviour (e.g., hiccoughing, coughing, fussing, or crying for long periods), or i f the l e v e l of the ambient noise became too high (e.g., trucks nearby, planes overhead, construction noises, noisy neighbours). The f i f t e e n -minute recording, then, did not always represent f i f t e e n con-secutive minutes. I f the c h i l d was obviously too fussy or too sleepy for a good recording to be obtained, E would reschedule the taping session. E kept records regarding the time and lo c a t i o n of the tape sessions, people, objects and animals ( i f any) present, the baby's mood at the time of recording, and the d i f f e r e n t i n t e r -actions that took place. 2.32. Spectrographic analysis 2.321. Instrumentation The tapes were reproduced on an Ampex 44OB tape recorder which was ca l i b r a t e d to give playback response c h a r a c t e r i s t i c s i e s s e n t i a l l y i d e n t i c a l to the Nagra IV-D tape recorder. Spec-trographic analysis was ca r r i e d out on a Kay Sonagraph, Model 7029A, with a frequency range of 80-8,000 Hz. 76 2.322. Selection and c l a s s i f i c a t i o n of utterances In the early phases of data analysis, a l l audible, harmonic portions of non-crying utterances were analyzed i n which there was no overlap of another person's voice and/or background noise. Since the production of spectrograms i s a time-consuming process and since there was a large amount of data to be analyzed, a sampling procedure was introduced. Under t h i s method, a maximum of f i f t e e n cind a minimum of f i v e utterances were analyzed per tape for each context. Every utterance was c l a s s i f i e d according to the context i n which i t occurred. These contexts were determined from comments on the tape and from E's record of the recording s i t u a t i o n . They were defined as follows: (1) C h i l d alone - S_: c h i l d v o c a l i z i n g with no apparent referent (2) C h i l d with object - SO: c h i l d v o c a l i z i n g while f i x a t e d v i s u a l l y on, or touching an object; i f the object was a noisemaker, an utterance emitted within 3 seconds of the noisemaker was classed as SO. Utterances were analyzed for a maximum of 3 objects per session: SOI, S02 and S03. (3) C h i l d with adult - SA: subcategorized into c h i l d with mother - SM, c h i l d with father - SF, c h i l d with adult f e -male - SAF, c h i l d with adult male - SAM. In order for an utterance to be classed i n t h i s category the c h i l d had to vocalize within 3 seconds of the adult's v o c a l i z a t i o n . Although c r i t i c i s m of the d e f i n i t i o n s i n (3) i s not unwarranted, i t was thought that a broader d e f i n i t i o n such as c h i l d i n the presence of an adult would produce more erroneous c l a s s i f i c a -tions of utterances, since one adult was usually present during 77 taping. Also, d i f f e r e n t i a l responses, i f such occurred would be obscured by such a c l a s s i f i c a t i o n . In the i n i t i a l phase of the i n v e s t i g a t i o n , the maximum i n t e r v a l between v o c a l i z a t i o n s of adult and c h i l d was 5 seconds. As the c h i l d ' s attention can s h i f t even within t h i s time i n t e r v a l , a shorter i n t e r v a l of 3 seconds was adopted. 2.323. R e l i a b i l i t y of context for the objects The r e l i a b i l i t y of the object context presented a problem with c e r t a i n subjects. A few of the mothers gave good commen-t a r i e s on the a c t i v i t i e s of t h e i r c h i l d r e n with the objects i n the environment; other mothers gave few comments. In the ab-sence of d i r e c t i v e comments on the tapes, the c l a s s i f i c a t i o n of utterances as SO was often subjective. This may have resulted i n some utterances being classed as SO when they should have been classed otherwise. In the same manner, some utterances which should have been classed as SO may have been included un-der some other context. However, i t seems u n l i k e l y that the data are skewed i n any given d i r e c t i o n . 2.324. Production of spectrograms Narrow-band spectrograms (45-Hz bandwidth f i l t e r ) were pro-duced for each utterance. A 500-Hz c a l i b r a t i o n tone was included on each spectrogram. The record, reproduce and mark l e v e l s were adjusted for each spectrogram. In t h i s manner, background noise and signal d i s t o r t i o n could be minimized. The gain control was adjusted such that the peak reading of the VU meter was between 78 0 a n d -2 dB. S p e c t r o g r a m s o f t h e r e f e r e n c e t o n e w e r e made a t 3- h o u r i n t e r v a l s t o e n s u r e t h a t t h e m a c h i n e was f u n c t i o n i n g c o n -s i s t e n t l y . 2.33. M e a s u r e m e n t o f s p e c t r o g r a m s 2 . 331. M e a s u r e m e n t o f f u n d a m e n t a l f r e q u e n c y F u n d a m e n t a l f r e q u e n c y was m e a s u r e d a t e i t h e r t h r e e o r f o u r p o i n t s i n e a c h u t t e r a n c e : b e g i n n i n g - p o i n t ( B E G I N ) , f i r s t m i d d l e -p o i n t ( F M P ) , s e c o n d m i d d l e - p o i n t (SMP) a n d e n d - p o i n t (END). BEGIN a nd END w e r e d e f i n e d , r e s p e c t i v e l y a s t h e o n s e t a n d d i s -a p p e a r a n c e o f a t l e a s t t h e t h i r d h a r m o n i c . MP was d e f i n e d a s a c h a n g e i n s i g n o f t h e s l o p e o f t h e f u n d a m e n t a l f r e q u e n c y ( F Q ) c o n t o u r . When two o r more c h a n g e s o c c u r r e d , t h e two c h a n g e s t h a t w e r e c o n s i d e r e d t h e m o s t c h a r a c t e r i s t i c w e r e c h o s e n f o r m e a s u r e m e n t . I f t h e r e was no f l u c t u a t i o n i n t h e F 0 c o n t o u r , t h e MP v a l u e was t a k e n a s t h e a v e r a g e o f t h e BEGIN a n d END v a l u e s . I n t h e m e a s u r e m e n t o f t h e a c o u s t i c a l p r o p e r t i e s o f a d u l t u t t e r a n c e s , t h e c a l c u l a t i o n o f F Q i s u s u a l l y b a s e d o n t h e mea-s u r e d v a l u e o f t h e t e n t h h a r m o n i c . M e a s u r e m e n t e r r o r a t t h i s l e v e l i s u s u a l l y m i n i m a l . I n i n f a n t u t t e r a n c e s , m e a s u r e m e n t o f F D b a s e d o n t h e t e n t h h a r m o n i c i s o f t e n n o t p o s s i b l e s i n c e t h i s h a r m o n i c i s n o t p r e s e n t i n m o s t c a s e s . I n o r d e r t o m i n i m i z e m e a s u r e m e n t e r r o r , t h e h i g h e s t v i s i b l e h a r m o n i c ( g e n e r a l l y t h e ' f i f t h ) was c h o s e n f o r m e a s u r e m e n t i n t h i s s t u d y . V The d i s t a n c e b e t w e e n t h e b a s e l i n e a n d t h e c h o s e n h a r m o n i c was m e a s u r e d w i t h c a l i p e r s . T h i s d i s t a n c e was t h e n r e a d a g a i n s t a t e m p l a t e ( b a s e d on a c a l i b r a t i o n t o n e o f 500 Hz) i n o r d e r t o d e t e r m i n e t h e v a l u e 79 o f t h e m e a s u r e d h a r m o n i c . T h e v a l u e o b t a i n e d w a s t h e n d i v i d e d b y t h e n u m b e r o f t h e h a r m o n i c i n o r d e r t o o b t a i n t h e f u n d a m e n t a l f r e q u e n c y . T h e s t a n d a r d e r r o r u s i n g t h i s m e t h o d w a s f o u n d t o b e ± 3 0 H z . 2 . 3 3 2 . C a l c u l a t i o n o f w i t h i n - u t t e r a n c e r a n g e T h e v a l u e . o f w i t h i n - u t t e r a n c e r a n g e w a s e q u a l t o t h e d i f -f e r e n c e b e t w e e n t h e m a x i m u m a n d m i n i m u m v a l u e s o f F D f o r e a c h u t t e r a n c e . T h i s v a r i a b l e i s d e n o t e d a s R A N G E t h r o u g h o u t t h e r e s u l t s a n d d i s c u s s i o n s e c t i o n s . 2 . 3 3 3 . M e a s u r e m e n t o f d u r a t i o n T h e d u r a t i o n ( d e n o t e d a s D U R ) o f a n u t t e r a n c e w a s e q u a l t o t h e d i s t a n c e b e t w e e n t h e B E G I N a n d E N D . I t w a s d e t e r m i n e d b y l a y i n g a c l e a r p l a s t i c t e m p l a t e o v e r t h e s p e c t r o g r a m . O n t h e t e m p l a t e , 1 . 2 3 c m = 1 0 0 m s e c . A c c u r a c y u s i n g t h i s m e t h o d w a s w i t h i n 5 0 m s e c , e x c e p t w h e n t h e u t t e r a n c e r e q u i r e d m o r e t h a n o n e s p e c t r o g r a m ( i . e . , w h e n t h e u t t e r a n c e w a s l o n g e r t h a n 2 . 4 s e c ) . M e a s u r e m e n t a c c u r a c y w a s n o t a s g o o d f o r t h e s e l o n g e r u t t e r a n c e s . 2 . 3 4 . S p e c i f i c a t i o n o f t h e o b j e c t s a n d o b j e c t c a t e g o r i e s A p p e n d i x A c o n t a i n s a l i s t o f a l l t h e o b j e c t s t h a t o c c u r r e d i n t h e a n a l y s i s o f e a c h s u b j e c t . S i n c e s u b d i v i d i n g e a c h o b j e c t c a t e g o r y a c c o r d i n g t o i n t o n a t i o n c o n t o u r r e s u l t e d i n m a n y g r o u p s h a v i n g a v e r y s m a l l s a m p l e s i z e , a c l a s s i f i c a t o r y s c h e m e w a s d e -v i s e d f o r t h e o b j e c t s w h e r e b y t h e s a m p l e s i z e c o u l d b e m a d e l a r g e e n o u g h f o r s t a t i s t i c a l a n a l y s i s . A s m e n t i o n e d e a r l i e r , 80 the SO-data were recoded into four major categories: V i s u a l (SV), Auditory + V i s u a l (SAV), T a c t i l e + V i s u a l (STV), and Auditory + T a c t i l e + V i s u a l (SATV). The r e c l a s s i f i c a t i o n of each object i s noted i n Appendix A. 2.35. C l a s s i f i c a t i o n of the contours A computer program was used to determine the intonation contour of each utterance. I f the fundamental frequency did not fluctuate more than ±5 Hz throughout the utterance, then that utterance was classed as l e v e l (L). An increase of more than 5 Hz from one measured point to the succeeding point was classed as a r i s e , while a decrease of more than 5 Hz from one point to the succeeding point was c l a s s i f i e d as a f a l l . Thus the follow-ing contours could be generated: r i s e (R), f a l l (F), r i s e - f a l l (RF), f a l l - r i s e (FR), r i s e - f a l l - r i s e (RFR), and f a l l - r i s e - f a l l (denoted as FRF). At each age l e v e l , a l l utterances were grouped (within each context) according to the intonation contour that they exhibited. Mean values and standard deviations of the variables BEGIN, FMP, SMP, END, RANGE and DUR were calculated for each contour.type. Since the contours R, F, L, RF and FR involve the measurement of one middle-point (with a few exceptions which are included i n the two middle-point category), the utterances having these contours were grouped and new means and standard deviations of the variables were calculated for each context. These averages constitute the IMP category. S i m i l a r l y , the RFR and FRF con-tours, which require a minimum of two middle-points for t h e i r 81 c l a s s i f i c a t i o n , were grouped and new means and standard deviations were calculated. Occasionally R, F, FR and RF contours appear under the two middle-point category because two middle-points were measured i n these utterances. In addition to the summary s t a t i s t i c s j u st described, o v e r a l l mean values and standard deviations of each variable i r r e s p e c t i v e of intonation contour or number of middle-points, were also c a l c u l a t e d f o r each context. 2 2.36. Hotelling's T tests 2 The Hotelling's T s t a t i s t i c can be used to t e s t the as-sumption that two samples a r i s e from the same population and have the same means on a given set of variables (Bjerring and Seagraves, 1972). One assumption made by t h i s t e s t i s that there i s homogeneity of covariances i n the two populations. In 2 addition to the T s t a t i s t i c , a confidence i n t e r v a l (1-a) x 100% i s calculated for the difference i n population means for each pair of corresponding v a r i a b l e s . Each confidence i n t e r v a l con-s t i t u t e s a univariate t e s t for that v a r i a b l e . I t must be re-membered that the univariate tests do not take i n t o account the covariances among the variables (Winer, 1971). , 2 In t h i s study, the Hotelling's T s t a t i s t i c was used to determine, for a given subject at a given age l e v e l , whether there were s i g n i f i c a n t differences between contexts — for both s i m i l a r and d i f f e r e n t types of utterances, and within contexts — for d i f f e r e n t types of utterances. Contrasts were c a r r i e d out on two l e v e l s : utterances classed according to the number of middle-points measured, and utterances classed according to 82 i n t o n a t i o n contour. A t o t a l of f i v e or more u t t e r a n c e s per con-t e x t was r e q u i r e d i n o r d e r f o r a c o n t r a s t t o be c a r r i e d out. Given a maximum o f t h r e e o b j e c t s per s e s s i o n , F i g u r e 1 shows the maximum p o s s i b l e types o f c o n t r a s t s t h a t c o u l d be performed (assuming a l a r g e enough sample) when u t t e r a n c e s are c l a s s e d a c c o r d i n g to the number of m i d d l e - p o i n t s measured. F i g u r e 2 o u t l i n e s the p o s s i b l e c o n t r a s t s i n v o l v e d i n comparing both s i m i -l a r and d i f f e r e n t i n t o n a t i o n c o n t o u r s . I n s e r t F i g u r e s 1 and 2 about here. 2.37. M u l t i p l e C l a s s i f i c a t i o n A n a l y s i s A computerized M u l t i p l e C l a s s i f i c a t i o n A n a l y s i s (MCA) p r o-gram (which i s p a r t of the OSIRIS I I I package a t the U n i v e r s i t y o f B r i t i s h Columbia) was used to f u r t h e r a n a l y z e the d a t a . V i a t h i s a n a l y t i c technique a s i n g l e v a r i a b l e can be r e l a t e d to sev-e r a l independent v a r i a b l e s or ' p r e d i c t o r s ' . The u n d e r l y i n g mathematics o f the MCA assume t h a t the d a t a f i t an a d d i t i v e model: Y. ., = Y + a. + b. + c. + ... l j k I j k where Y i s the grand mean of the dependent v a r i a b l e , and a^, b j , and c^, e t c . are n u m e r i c a l c o e f f i c i e n t s r e p r e s e n t i n g the main e f f e c t s due t o the independent v a r i a b l e s ( p r e d i c t o r s ) P , P^, P , e t c . c' 83 1 MP vs 1 MP S x SOI S x S02 S x S03 SOI x S02 501 x S03 502 x S03 2 MP vs 2 MP S 1 x SOI' S 1 x S02 1 S" x S03 1 SOI 1 x S02 1 SOI' x S03' S02' x S03' 1 MP vs 2 MP S x S' S x SOI 1 S x S02' S x S03' SOI x S' SOI x SOI 1 SOI x S02' SOI x S03 1 S02 x S 1 S02 x SOI* S02 x S02' , S02 x S03 1 S03 x S' S03 x SOI' S03 x S02' S03 x S03' Figure 1. Maximum possible contrasts occurring when utterances are examined according to number of middle-points. 84 RF x RF FR x FR R x R F x F L x L RFR x RFR FRF x FRF The above contrasts could be performed for each of the following contexts: S x SOI SOI x S02 S x S02 SOI x S03 S x S03 S02 x S03 Contrasts of d i f f e r e n t intonation contours could be performed across contexts (as described above) and within contexts: S x S 501 x SOI 502 x S02 503 x S03 The following contrasts are po s s i b l e : RF x FR FR x F R x FRF RF x R FR x L F x L RF x F FR x RFR F x RFR RF x L FR x FRF F x FRF RF, x RFR R X F L x RFR RF x FRF R x L L x FRF FR x R R x RFR RFR x FRF Figure 2. Contour contrasts. 85 The output of the MCA program shows the e f f e c t s of each predictor both before and a f t e r the e f f e c t s of the other v a r i -ables have been taken into consideration. We can thus observe the trends of the actual data, as well as the goodness-of-fit of the predicted data to the actual data. Where the f i t of the predicted curve i s good, the additive model can be said to apply to the data. Where the f i t of the predicted curve to the actual data i s poor, we can conclude that e i t h e r the additive model does not apply, or that the variance i s not t o t a l l y explained by the predictors under consideration. In the l a t t e r case, the addition of other factors might improve the f i t of the curve i f indeed the data f i t an additive model. Another factor which could contribute to the poor f i t of any predicted curve could be the categories of data being analyzed. I f the data have not been grouped appropriately then the predicted curve probably w i l l not show an optimal f i t . Other features of the MCA program i n -clude the advantage of using either i n t e r v a l , o r d i n a l or nominal scales of the data. Equal numbers of observations i n each cate-gory are not required. One r e s t r i c t i o n i s that there should be many more cases than degrees of freedom i n the p r e d i c t i v e model — where df - (the sum of the number of categories for each of the predictors) — ( t o t a l number of p r e d i c t o r s ) . A disadvantage of the MCA program i s that i t does not take interactions among the dependent variables into account (Andrews et a l . , 1967). For the present study the independent variables used i n the MCA were age, context and subject. Chronological age, Bayley Mental score and Bayley Motor score were examined separately as 86 age metrics. Due to r e s t r i c t i o n s i n the MCA program involving the number of categories and the number of cases per category the data were grouped into a number of age i n t e r v a l s . These i n t e r v a l s were defined such that trends of the data observed i n weekly or biweekly i n t e r v a l s would not be obscured. Chrono-l o g i c a l age was analyzed i n ten age i n t e r v a l s of f i v e weeks each. The f i r s t and tenth i n t e r v a l s were s l i g h t l y greater, i n order to accommodate cases at the extreme ends of the age scale. The following i n t e r v a l s were examined ( a l l numbers r e f e r to age i n weeks): 0-10, 11-15, 16-20, 21-25, 26-30, 31-35, 36-40, 41-45, 46-50 and 51-60. The Bayley Mental scores were analyzed i n eleven age i n t e r v a l s of ten points each as follows: 0-10, 11-20, 21-30, 31-40, 41-50, 51-60, 61-70, 71-80,.81-90, 91-100, and 101-110. The Bayley Motor scores were analyzed i n eleven i n t e r v a l s of f i v e points each as follows: 0-5, 6-10, 11-15, 16-20, 21-25, 26-30, 31-35, 36-40, 41-45, 46-50 and 51-55. A t o t a l of seven contexts were examined — S, SM, SOP, SV, SAV, STV and SATV. The SM and SOP contexts were included for purposes of the larger study and t h e i r r e s u l t s w i l l be examined where appropriate. Preliminary analysis indicated that grouping the SF, SAM, and SAF contexts into a new category c a l l e d S plus other person (SOP) would not obscure r e l a t i o n s h i p s between these contexts. The data from 108-M were included since separate MCA runs made both omitting and including t h i s subject were found to show l i t t l e difference i n terms of the grand means. The dependent variables employed i n the analysis were DUR, RANGE, mean F , and two indices R/D and mean F x D x R. The 87 variable mean F Q was used rather than analyzing BEGIN, FMP, SMP and END separately since preliminary analysis showed l i t t l e d i f -ference among the four variables of F . For utterances having one measured middle-point the F Q was taken as (BEGIN + FMP + END)/3. The mean F Q for utterances having two measured middle-points was calculated as (BEGIN + FMP + SMP + END) /4. R/D and mean F Q x D x R were index values created from the dependent variab l e s . Using chronological age, context and subject as pre-d i c t o r s the variables RANGE, DUR and mean F Q were analyzed for a l l subjects, and then for males only and females only. The Bayley age metrics were employed as predictors along with con-text and subject for a l l subjects only. The indices of R/D and mean F Q x D x R were analyzed for a l l subjects using chronolog-i c a l age, context and subject as pre d i c t o r s . The r e s u l t s for each analysis were graphed showing both the actual and predicted data curves. 2.38. M u l t i v a r i a t e Nominal Scale Analysis The M u l t i v a r i a t e Nominal Scale Analysis (MNA) i s the nominal scale version of the MCA program. Unlike the MCA, t h i s program does not work on the p r i n c i p l e of an additive model. The MNA program was employed i n order to obtain frequency d i s -t r i b u t i o n s of the intonation contours and the various contexts according to chronological age (in ten age l e v e l s as previously described), subject and sex. A d i s t r i b u t i o n of the intonation contours i n each context was also generated. 88 2.39. D e v e l o p m e n t o f t h e i n t o n a t i o n c o n t o u r s w i t h age A p r o g r a m known a s FMEANS (a one-way a n a l y s i s o f v a r i a n c e p r o g r a m w h i c h i s a l s o a p a r t o f t h e O S I R I S I I I p a c k a g e ) was u s e d t o c o m p u t e t h e means a n d s t a n d a r d d e v i a t i o n s o f t h e v a r i a b l e s B EGIN, FMP, SMP, END, DUR and RANGE i n t h r e e g r o s s a g e c a t e g o r i e s (0-21 w e e k s , 22-38 w e e k s , a n d 39-60 w e e k s ) i n o r d e r t o show t h e g e n e r a l c h a n g e s t h a t o c c u r r e d w i t h i n e a c h c o n t o u r o v e r t i m e . The means w e r e c a l c u l a t e d i r r e s p e c t i v e o f c o n t e x t . CHAPTER 3 Results 3.0. Introduction This section includes the r e s u l t s of the following s t a -2 t i s t i c a l analyses: Hotelling's T contrasts (3.1), Multiple C l a s s i f i c a t i o n Analysis (3.2 and 3.3), FMEANS (3.4), and M u l t i v a r i a t e Nominal Scale Analysis (3.5). 2 3.1. Hotelling's T contrasts The r e s u l t s reported here represent only a portion of the possible contrasts that could have been c a r r i e d out had there not been a constraint on sample size of the data with respect to the computer programs a v a i l a b l e . In order for a Hotelling's contrast to be c a r r i e d out, each context under comparison must contain at l e a s t f i v e utterances. An a d d i t i o n a l constraint on the data i s that i f the solution to the equation : (n^ + - 2) - p + 1 where n^ = number of utterances for context (1) = number of utterances for context (2) p = number of variates i s less than 8, the F - p r o b a b i l i t y cannot be computed. A t o t a l of 666 Hotelling's contrasts were calculated. Of these, 432 (or 64.9%) were s i g n i f i c a n t beyond the 5% l e v e l . The incidence of s i g n i f i c a n t tests depended on the type of con-t r a s t being performed, as w i l l be seen below. In addition to 89 90 the value, F-value and F - p r o b a b i l i t y , (1-a) x 100% (where a = 0.05) confidence i n t e r v a l s were computed for each p a i r of corresponding variables; t h i s constituted a univariate t e s t for each variable under examination. 3.11. Contrasts of utterances with a single middle-point A t o t a l of 95 Hotelling's tests were performed to determine whether the combined data for those intonation contours i n which only one middle-point was measured d i f f e r e d for the subject alone and subject plus object conditions, or for utterances produced i n the context of d i f f e r e n t objects. Only 19 (or 20% of the total) contrasts were s i g n i f i c a n t at the f i v e percent l e v e l or bettwe, i n d i c a t i n g that there was l i t t l e d i fference between the contexts when the contours were grouped i n t h i s manner (cf. Table VI). Only one univariate t e s t (FMP of S x RATTLE for 104-F at 9 weeks was s i g n i f i c a n t . Insert Table VI about here. 3.12. Contrasts of utterances with two middle-points Since the majority of the intonation contours produced by the infants involved the measurement of only one middle-point, only nine contrasts could be performed for those utterances i n which two middle-points were measured. One of these contrasts was s i g n i f i c a n t (see Table VI), and none of the univariate tests 91 TABLE VI SIGNIFICANT CONTRASTS FOR UTTERANCES HAVING THE SAME NUMBER OF MIDDLE-POINTS ID AGE (wks) CONTRAST (IMP x IMP) df T 2 F uni-var. L02-F 54 54 S (IMP) x KEYS (IMP) S(1MP) x SLIPPER(IMP) 12,7 12,6 21.54 23.01 3.400* 3.580* L04-F 9 16 16 20 24 24 26 S(1MP) x RATTLE(IMP) S(1MP) x MOBILE(IMP) MOBILE(IMP) x MIKE(IMP) S(1MP) x GREEFROG(IMP) S(1MP) x EATINCUP(IMP) HAIRDOLL(IMP) x EATINCUP(IMP) S(IMP) x EATINCUP(IMP) 91,64 15,15 15,29 52,28 8,21 21,21 19,21 20.00 16.76 30.65 13.84 17.00 32.77 19.46 3.897** 2.905* 5.573*** 2.629* 2.932* 5.930*** 3.503* FMP 105-M 53 DUCK(IMP) x TAPERECR(IMP) 8,9 22.10 3.380* 106-F 50 S(1MP) X TOYMOUSE(IMP) 11,10 23.38 3.785* L07-M 23 S(1MP) x SQUDUCK(IMP) 6,7 27.31 3.781* L09-M 32 41 44 S(IMP) x TOYBOATS(IMP) S (IMP) x MIKE (IMP) S(IMP) x JUMPROPE(IMP) 8,7 9,15 15,9 24.86 19.05 18.37 3.645* 3.176* 3.062* 111-M 14 18 28 40 S(1MP) x BLUBUNNY(IMP) RAGDOLL(IMP) x ELEPHANT(IMP) S(1MP) x BLUBUNNY(IMP) S(1MP) x BOWL(IMP) 7,10 9,11 7,8 9,8 23.88 20.25 35.84 25.49 3.652* 3.239* 5.257* 3.899* ID AGE CONTRAST (2MP x 2MP) df rj>2 F 104-F 24 HAIRDOLL(2MP) x EATINCUP(2MP) 18,15 29.13 4.120** * £ < .05 ** p < .01 *** p_ < .001 92 were s i g n i f i c a n t . Again, the r e s u l t s indicated that there was l i t t l e or no difference between contexts based on t h i s c l a s s i f i -cation of the utterances. 3.13. Contrasts involving the same intonation contours 3.131. Intonation contours having one measured middle-point Table VII presents the r e s u l t s of 57 Hotelling's tests involving pairwise comparisons of s i m i l a r intonation contours which occurred i n d i f f e r e n t contexts. Nine of these tests (or 15%) were s i g n i f i c a n t at the f i v e percent l e v e l or better, i n -dicating that the subjects generally did not v o c a l l y d i f f e r e n -t i a t e between the S and SO states; only two univariate tests were s i g n i f i c a n t . I t can be seen that the majority of the con-t r a s t s involved RF contours. The RF contour was the most f r e -quently occurring contour for a l l subjects and accounted for over f o r t y percent of the utterances. The sample siz e of the other intonation contours i n t h i s category (FR, R, F and L) was not usually large enough for Hotelling's contrasts to be con-s i s t e n t l y c a r r i e d out. Insert Table VII about here. 3.132. Intonation contours having two measured middle-points Due to problems i n sample s i z e , only three contrasts ( a l l involving 104-F) for RFR and FRF contours could be performed 9 3 TABLE VII CONTRASTS INVOLVING THE SAME INTONATION CONTOURS ID AGE (wks) CONTRAST df T2 F uni-var. 102-F 41 S(RF) x SNOOPY(RF) 9,7 11.72 1.758 50 S (RF) x CANDLE (RF) 9,5 3.303 .4719 54 S(RF) x KEYS(RF) 11,6 16.90 2.585 54 S(RF) x SLIPPER(RF) 11,6 20. 64 3.156* 54 KEYS(RF) X SLIPPER(RF) 6,6 1.149 .1532 103-M 22 S(RF) X BELLS(RF) 18,7 4.355 .7316 104-F 7 ' S(RF) x PINKTEDD(RF) 10,5 3.532 .5180 7 S(F) x PINKTEDD(F) 7,11 13.37 2.079 9 S(FR) x RATTLE(FR) 16,14 30.13 5.222** FMP/ END 9 S(R) x RATTLE(R) 16,13 6.537 1.127 9 S(F) X RATTLE(F) 28,17 3.645 .6642 14 SNOOPY(RF) x CLOWN(RF) 7,20 1.270 .2164 14 SNOOPY(F) x CLOWN(F) 10,32 2. 294 .4150 16 S(RF) x MIKE(RF) 9,20 7.325 1.263 20 S(RF) x GREEFROG(RF) 20,17 19.75 3.523* 20 S(RFR) X GREEFROG(RFR) 9,5 14.50 1.554 20 S(FRF) X GREEFROG(FRF) 8,14 3.822 .4922 24 S(RF) x HAIRDOLL(RF) 4,16 3.210 .5136 24 S(RF) x EATINCUP(RF) 4,17 11.49 1.861 24 HAIRDOLL(RF) x EATINCUP(RF) 16,17 28.01 4.923** 1 24 HAIRDOLL(RFR) X EATINCUP(RFR) 10,10 14.37 .1668 26 S(RF) x EATINCUP(RF) 11,20 8.763 1.526 105--M 23 S(RF) x BOOKS(RF) 19,4 1.674 .2766 106--F 18 S(RF) x LION(RF) 18,6 8.862 1.477 24 S(RF) x PUPPY(RF) 7,6 6.185 .9436 28 S(RF) x YELORATT(RF) 6,9 4.042 .6457 94 TABLE VII (continued) ID AGE (wks) CONTRAST df T2 F uni-var. 106 -F 50 S (RF) X BLOCKS(RF) 10,4 16.41 2.345 50 S (RF) X TOYMOUSE(RF) 10,4 15.72 2.246 54 S (RF) X BLANKET(RF) 8,4 10.54 1.405 109 -M 13 S (RF) X MOTHRING(RF) 11,4 3.782 .5547 35 S (RF) X BALL(RF) 14,4 5.476 .8518 41 S (RF) X MIKE(RF) 8,8 14.64 ,2.196 44 S (RF) X JUMPROPE(RF) 13,5 10.92 1.699 110 -M 41 S (RF) X MIKE(RF) 8,5 2.243 . 3105 111 -M 12 MOBILE(RF) x TEDDY(RF) 6,8 12.72 1.818 14 S (RF) X RAGDOLL(RF) 7,9 12.89 1.934 14 S (RF) X TEDDY(RF) 7,6 18.86 2.611 14 S (RF) X BLUBUNNY(RF) 7,10 23.88 3.652* 14 RAGDOLL(RF) x TEDDY(RF) 9,6 3.105 .4554 14 RAGDOLL(RF) x BLUBUNNY(RF) 9,10 5.006 .7904 14 TEDDY(RF) X BLUBUNNY(RF) 6,10 .2569 .3854 E-01 15 S (RF) X RAGDOLL(RF) 6,9 12.75 1.870 15 S (RF) X BLUBUNNY(RF) 6,10 13.16 1.975 -15 RAGDOLL(RF) x BLUBUNNY(RF) 9,10 12.58 1.987 18 S (RF) X RAGDOLL(RF) 8,9 8.029 1.228 18 S (RF) X BLUBUNNY(RF) 8,11 12.48 1.971 18 S (RF) X ELEPHANT(RF) 8,11 9.280 1.465 18 RAGDOLL(RF) x BLUBUNNY(RF) 9,11 4.952 .7924 18 RAGDOLL(RF) x ELEPHANT(RF) 9,11 20.25 3.239* 18 BLUBUNNY(RF) x ELEPHANT(RF) 11,11 4.659 .7624 24 S (RF) X RADIO (RF) 7,6 8.560 1.185 28 S (RF) X BLUBUNNY(RF) 5,8 32.22 4.462* 28 S (RF) X PLUTODOG(RF) 5,12 11.27 1.724 28 BLUBUNNY(RF) X PLUTODOG(RF) 8,12 3.493 .5588 32 S (RF) X MOBILE(RF) 6,6 8.322 1.110 95 TABLE VII (continued) ID AGE (wks) CONTRAST df T2 F uni-var. 111-M 40 S (RF) x BOWL (RF) 7,6 30. 86 4.273* 115-F 24 S(RF) x POOH(RF) 7,10 3. 912 .5983 116-F 22 S(RF) x RABBIT(RF) 8,6 37.38 5.339* 118-F 19 S(RF) x GUNK(RF) 7,10 12.65 1.935 * £ < .05 ** p < .01 96 (see Table VII). None of these contrasts was s i g n i f i c a n t , nore were there any s i g n i f i c a n t univariate t e s t s . 3.14. One middle-point vs two middle-point contrasts Of the 164 Hotelling's contrasts performed i n t h i s category, 82 (or approximately 50%) were s i g n i f i c a n t at the f i v e percent l e v e l or better. There were only 33 s i g n i f i c a n t univariate tests out of a possible 820 which were performed. Two-thirds of these s i g n i f i c a n t univariates involved the variable DUR. An ad d i t i o n a l eight involved the va r i a b l e RANGE. In a l l instances, when a univariate test was s i g n i f i c a n t f o r RANGE or DUR, the mean value of the variable concerned was higher for the two middle-point utterances than for the one middle-point utterances under comparison. It was previously reported by Handford (1972) that the duration of utterances having two measured middle-points was s i g n i f i c a n t l y longer than that of utterances having one measured middle-point. The within-utterance range for two middle-point utterances was also found to be greater than that of one middle-point utterances. The present data confirm Handford's findings. Since h a l f of the contrasts for one vs two measured middle-points were s i g n i f i c a n t , any amalgamation of data from these two categories (as i n Handford, 1972) should be ser i o u s l y questioned. Our r e s u l t s indicate that these two types of utterances are d i f -ferent, e s p e c i a l l y with respect to range and duration. Grouping these two types of utterances together obscures not only t h e i r / 97 differences but also any developmental changes that may be occurring. 3.15. Contrasts of d i f f e r e n t intonation contours The argument for analyzing the data separately according to number of middle-points measured or intonation contour i s further 2 supported by the r e s u l t s of Hotelling's T contrasts for d i f f e r e n t intonation contours. A t o t a l of 347 contrasts of d i f f e r e n t i n -tonation contours, occurring i n ei t h e r the same context or d i f -ferent contexts, were performed; of these, 320 (or 92.2%) were s i g n i f i c a n t at the f i v e percent l e v e l or better; many were s i g -n i f i c a n t beyond the one percent l e v e l . These r e s u l t s would seem to suggest that grouping the utterances according to intonation contour i s a more reasonable way to examine the data than group-ing i r r e s p e c t i v e of contour. The r e s u l t s of the contrasts of sim i l a r intonation contours indicate that the contours them-selves are r e l a t i v e l y uniform; otherwise one would have observed more s i g n i f i c a n t contrasts i n t h i s category. One proviso must be made, however, with regard to those few instances i n which two middle-points were measured for RF, FR, R and F contours. These utte::ances are generally longer than t h e i r one middle-point counterparts, and therefore a grouping of these two types of utterances would be suspect. i A t o t a l of 136 univariate tests were s i g n i f i c a n t at the f i v e percent l e v e l . Well over half ( 83 ) of the tests were s i g n i f i c a n t for the variables BEGIN, FMP and END, and 47 of these s i g n i f i c a n t tests were a t t r i b u t a b l e to differences i n FMP. 98 In the majority of these s i g n i f i c a n t contrasts, F Q increased i n one contour and decreased i n the other (e.g., as i n RF x FR or RF and FRF which accounted f o r 30/47 s i g n i f i c a n t contrasts of FMP). Contrasts of one vs two middle-point contours accounted for 10/16 s i g n i f i c a n t univariate tests for the variable RANGE and 31/37 s i g n i f i c a n t univariate tests for the variable DUR. 3.16. Examination of cases having small sample sizes 2 Where the sample size was too small for the Hotelling's T s t a t i s t i c and associated p r o b a b i l i t i e s to be computed, the data were otherwise inspected to determine whether the mean values of the variables d i f f e r e d s i g n i f i c a n t l y . Only s i m i l a r intonation contours were compared since these contrasts were of prime i n -te r e s t i n t h i s study. Given the rather large standard deviations, there was generally no difference between e i t h e r the means for the S_ and SO conditions or between d i f f e r e n t SO conditions, at the same age l e v e l . Those substantial differences that were ob-served were usually associated with sample sizes of one or two utterances; consequently, i t i s d i f f i c u l t to assess whether they were a c t u a l l y i n d i c a t i v e of d i f f e r e n t i a l v o c a l i z a t i o n . I t would seem more l i k e l y that these differences are a r t i f a c t s of small sample s i z e . 3.2. Comparison of the age metrics: chronological age, Bayley  Mental score and Bayley Motor score Figure 3 shows the r e s u l t s of analyzing the changes of mean F , DUR.and RANGE over time using three d i f f e r e n t age metrics: chronological age, Bayley Mental score and Bayley Motor score. 99 I t i s evident that changing the metric only s l i g h t l y a l t e r s the configuration of the graph. Insert Figure 3 about here. A peak i n mean F Q (370 Hz) i s observed at 28 weeks chrono-l o g i c a l age, and at scores of 65 on the Bayley Mental scale and 28 on the Bayley Motor scale. The Bayley Mental score i s equi-valent to a chronological age of 24 weeks, while the Bayley Motor score has an age equivalent of 26 weeks. Since the,age values used are midpoints of predefined i n t e r v a l s , the peaks of the three graphs are tantamount to equivalent. Peak values i n DUR are found to occur at 23 weeks (760 msec), 38 weeks (865 msec) and 48 weeks (755 msec) chronological age. Using Bayley Mental score as an age metric, DUR peaks at scores of 65 (760 msec) and 85 (830 msec). The Mental scores correspond to chronological ages of 24 and 39 weeks re s p e c t i v e l y . Peaks on the Bayley Motor score graph occur at 18 (695 msec), 28 (755 msec) and 38 (820 msec). The motor scores correspond to chronological ages of 19, 2 6 and 3 9 weeks respe c t i v e l y . Since the three age classes span s l i g h t l y 1 d i f f e r e n t i n t e r v a l s , t h e i r maximum values w i l l not necessarily coincide, but i t i s evident that the values do not d i f f e r to a great extent. For example, at approximately 38 weeks values of 865 msec, 830 msec and 820 msec are observed 7 13 18 23 28 33 38 43 48 53 AGE (MIDPOINTS OF 5-WK INTERVALS) 5 15 25 35 45 55 65 75 85 95 105 BAYLEY MENTAL SCORE (MIDPOINTS OF 10-PT INTERVALS) 2.5 125 22.5 32.5 425 525 BAYLEY MOTOR SCORE (MIDPOINTS OF 5-PT INTERVALS) FIGURE 3. A l l Subjects (N =19): Means of F c, duration, and within-utterance range with respect to chronological age and the mental and motor scores based on the Bayley Scales of Infant Development. Solid l i n e s re-present the averaged data; dashed l i n e s are predicted curves based on the MCA additive model; horizontal l i n e s correspond to the o v e r a l l means. o o 101 for chronological age, Bayley Mental score and Bayley Motor score respectively. RANGE i s observed to peak at 28 (102 Hz), 38 (106 Hz) and 48 weeks (100 Hz) chronological age. Using the Bayley Mental score, peak values occur at 35-45 (98 Hz) and 65 (196 Hz). The f i r s t i n t e r v a l corresponds to a chronological age of 13-17 weeks while the second score i s equivalent to 24 weeks. Maximum values of RANGE are observed at Motor scores of 18 (99 Hz), 28 (103 Hz) and 38 (105 Hz) The age equivalents of these peaks are 19, 26 and 39 weeks. The best f i t s of the MCA predicted curves (see dashed l i n e s , Figure 3) are observed when chronological age i s used as the age metric. The predicted curves for mean F Q have the best f i t of a l l the Bayley score curves. Predicted curves for RANGE and DUR vs Bayley scores do not f i t the measured data as w e l l . This i s e s p e c i a l l y true for the extreme low and high Bayley scores. The poor f i t for the low Bayley scores may be a t t r i b u t a b l e to the r e l a t i v e l y poor r e l i a b i l i t y of the r e s u l t s of psychological tests i n very young i n f a n t s . I t must also be noted that the averages of the variables i n both end classes of the Bayley score graphs do not necessarily represent equal numbers of subjects, and therefore the predicted curves deviate somewhat at these points. The use of the Bayley scores as measures of development does not appear to provide any a d d i t i o n a l information to that furnished by chronological age, nor does i t improve p r e d i c t i v e power. For these reasons, chronological age i s used as the age metric i n the 102 remainder of t h i s study. No attempt has been made to examine the actual Bayley te s t items i n r e l a t i o n to the r e s u l t s but i t i s possible that c e r t a i n of the observations, e s p e c i a l l y those regarding the peaking behaviour of the va r i a b l e s , coincide with the successful completion of c e r t a i n items on the Bayley Scales. A factor a n a l y t i c study would be needed to e l i c i t such trends. 3.3. Results of Multiple C l a s s i f i c a t i o n Analysis 3.31. Age and sex trends of the dependent variables and two  related indices As can be seen i n Figure 4, the average F Q centers around 355 Hz for a l l subjects and does not vary appreciably with age, except for a s l i g h t peak between 26 and 30 weeks. The peaking behaviour i s s t i l l observed when the data are subdivided according to the sex of the subject (Figures 5 and 6) except a broader peak (21-30 weeks) i s observed i n the case of the f e -males. The mean F Q for the female subjects (370 Hz) i s con-s i s t e n t l y 25 ± 20 Hz higher than that of the males (345 Hz). The mean F Q of the females r i s e s from an i n i t i a l value of 365 Hz to a peak value of 380 Hz, and then decreases to 370 Hz by the end of the f i r s t year of l i f e . The males' mean F r i s e s from 350 Hz u o at b i r t h to a peak value of 360 Hz and then drops to 325 Hz by about one year of age. Insert Figures 4, 5 and 6 about here. z 200- - " < UJ 01 i i i i I i i i i i i i I I _ I i i i i L _ J i i i i i i i i i i i Ol i I I I I i i i i i i i I i i i i i i i i i i i i — i — i i i i — i — i 7 13 18 23 28 33 38 43 48 53 S SM SOP SV SAV STV SATV 2 4 6 8 10 12 14 16 18 AGE (MIDPOINTS OF 5-WK INTERVALS) CONTEXT SUBJECT FIGURE 4. A l l Subjects (N = 19): Means of F D, duration, and within-utterance range (11,368 v o c a l i z a t i o n s ) . Solid l i n e s represent the averaged data; dashed li n e s are predicted curves based on the MCA additive model; horizontal lines correspond to the ov e r a l l means. 200 0 13 800-% E -z o < 400-cc nl i • i i i i i i — _ J 1 I 1 1 1 L 7 13 18 23 28 33 38 43 48 53 AGE (MIDPOINTS OF 5-WK INTERVALS) SM SOP SV SAV STV SATV CONTEXT 4 6 15 SUBJECT 16 18 FIGURE 5. Females (N = 7): Means of F Q, duration, and within-utterance range (4,540 voc a l i z a t i o n s ) . Solid l i n e s represent the averaged data; dashed li n e s are predicted curves based on the MCA additive model; horizontal l i n e s correspond to the ov e r a l l means. cc 5Cf Ol i • • • • i • • • i I i i i i i i i I i i — i — i — i — i — i — i — i — i — i — i 7 13 18 23 28 33 38 43 48 53 S SM SOP SV SAV STV SATV 3 5 7 8 9 10 11 12 13 14 17 19 AGE (MIDPOINTS OF 5-WK INTERVALS) CONTEXT SUBJECT FIGURE 6. Males (N = 12): Means of F Q, duration, and within-utterance range (6,828 voc a l i z a t i o n s ) . Solid l i n e s represent the averaged data; dashed li n e s are predicted curves based on the MCA additive model; horizontal l i n e s correspond to the ove r a l l means. 106 A l l graphs of DUR vs AGE show an increase i n DUR with age (Figures 4, 5 and 6). The average DUR of an utterance i s 660 msec for a l l subjects; when sex i s considered, the averages are 635 msec f o r females and 675 msec for males. The males' utterances are longer i n duration from b i r t h to 25 weeks, whereas the duration of the females' utterances has the higher value from 26 weeks to about one year (with one exception at 4 6-50 weeks where males' and females' utterances are e s s e n t i a l l y equal i n length). The average difference i n length between males' and females' utterances i s never larger than 130 msec which, i n view of the standard deviations observed for DUR (averaging 500 msec), may not be large enough to i n f e r a sex difference i n the sample'. The average DUR of the females' utterances increases from 375 msec at b i r t h to a peak value of 775 msec between 26 and 30 weeks; a second peak value of 900 msec i s observed between 36 and 40 weeks. The DUR then decreases to 645 msec by approximately one year of age. In the case of the males, DUR increases from 430 msec at b i r t h to a peak value of 805 msec at 26-30 weeks. A second peak value (815 msec) i s observed at 36-40 weeks, and a t h i r d peak (755 msec) occurs at 46-50 weeks. The male in f a n t s ' average utterance i s about 605 msec by one year of age. The graph of DUR vs AGE for a l l subjects (Figure 4) exhibits three peaks at the same age l e v e l s as were observed for the males. Since there were more male subjects and thus more male utterances, the graph f o r a l l subjects i s l i k e l y weighted i n favor of the male subjects. 107 The within-utterance range of the females' utterances (Figure 5) exhibits a gradual increase (with some fluctuation) from 80 Hz at b i r t h to 110 Hz by one year of age. The males, on the other hand, exhibit an increase i n RANGE from 85 Hz at b i r t h to 105 Hz at 36-40 weeks, and then a decrease to 80 Hz by one year (see Figure 6). Since the terminal portions of the graphs for males and females are changing i n opposite d i r e c t i o n s , the graph of RANGE vs AGE for a l l subjects (Figure 4) exhibits a r i s e i n i t i a l l y , followed by a r e l a t i v e l y l e v e l terminal portion. The graph showing the change i n the r a t i o of RANGE to DUR (R/D) with age (Figure 7) i s bowl-shaped, beginning at a high value (0.26) at 0-10 weeks, decreasing to a minimum at 36-40 weeks (0.16) and then increasing i n i t s terminal portion. The shape of the graph indicates that RANGE and DUR are r e l a t i v e l y independent v a r i a b l e s . The change of the second index -7 mean Fo x D x R (x 10 ) with age i s also graphed i n Figure 7. This index value increases with age, peaking at 21-25 weeks (3.45), 36-40 weeks (4.06) and 46-50 weeks (3.04). This graph rather dramatically shows the peaking behaviour observed with the i n -d i v i d u a l v a r i a b l e s . (See Appendix B for the actual values of the variables on which Figures 4, 5, 6 and 7 are based.) _ ^ . = = — --- i Insert Figure 7 about here. FIGURE 1. A l l Subjects (N = 19): Means of Range to Duration and of mean F Q x Duration x Range. Solid l i n e s represent the averaged data; dashed li n e s are predicted curves based on the MCA additive model; horizontal l i n e s correspond to the ove r a l l means. o oo 109 3 . 3 2 . The use of CONTEXT as a predictor Mean values of the three v a r i a b l e s : mean F , DUR and RANGE, i n addition to the two ind i c e s : R/D and mean F Q x D x R, were calculated for each of the contexts (see Figures 4 , 5 , 6 and 7 ) . In t h i s manner i t could be determined whether the c h i l d was a l t e r i n g his/her vocal output i n a p a r t i c u l a r manner depending on the context of the utterance. The graphs of mean F Q vs CONTEXT are seen to be essen-t i a l l y unremarkable, with a l l values l y i n g close to the grand mean. The predicted curves f i t the actual data with the ex-ception of a s l i g h t discrepancy i n the SAV context for males and females. This would indicate that the additive model can be applied to the data but i n the case of the SAV context i t does not explain a l l of the variance. This context a c t u a l l y played a minimal r o l e i n t h i s study because i t contained few objects and very few utterances. I t i s possible that the objects could have been placed i n a more appropriate category or categories. The mean F Q for the SV and SAV categories i s , on the average, 20 Hz lower than the grand mean. The SATV category i s noted to be 30 Hz below the mean for the females' utterances. These values are within the range of measurement error for spectro-g r a p h s analysis (Lindblom, 1 9 6 2 ). They are also associated with r e l a t i v e l y low sample size s . Generally, the S_, SM and SOP contexts l i e close to the grand mean for DUR, while the SO contexts tend to deviate somewhat. A l l values are well within one standard deviation of the mean. 110 The STV category i s usually closer to the grand mean than the other categories. This category also had the large s t number of observations and therefore the deviations of the remaining SO contexts from the mean may be a r e f l e c t i o n of low sample s i z e . The mean DUR for the SV context i s con s i s t e n t l y lower than the grand mean for a l l contexts f o r males, females and a l l subjects. Such consistencies are not noted with the other two object con-texts: the values of the SAV and SATV contexts are consistently higher than the grand mean fo r males and lower than the grand mean for females. The S, SM and (for the most part) STV contexts are close to the grand mean i n a l l graphs of RANGE vs CONTEXT. The average RANGE of the SOP category i s consistently higher than the grand mean. The mean values of the SV, SAV and SATV contexts a l l l i e below the grand mean of RANGE for the females, with the SAV and SATV contexts showing the largest deviations from the grand mean. In the case of the males, the SO categories a l l e x h i b i t a s l i g h t l y lower mean RANGE than the grand mean. For both males and females the deviations observed are well within one standard deviation (75 Hz) of the mean. The graphs of R/D and mean F q x D x R vs CONTEXT (see Figure 7) are e s s e n t i a l l y mirror images of each other. One would expect t h i s behaviour knowing the mathematical nature of these two in d i c e s . The S, SM and STV categories are generally close to the grand mean while the SOP and remaining SO categories usually show a deviation from the grand mean. I l l The MCA predicted curves for DUR, RANGE, R/D and mean F Q x D x R vs CONTEXT generally show a good f i t for the S, SM and SOP contexts and a poor f i t for the SO contexts. I t seems that the additive model may not apply for CONTEXT as a predictor. I t i s also possible that the data may have been i n -appropriately c l a s s i f i e d i n terms of the four object contexts chosen; likewise, an additive model may not be - appropriate for predicting data classed according to context. The l a t t e r seems rather u n l i k e l y given the r e l a t i v e l y good f i t of the model to the S, SM and SOP contexts. One requirement of the MCA (or any v. other s t a t i s t i c a l procedure f o r that matter) i s that there must be enough cases i n each category to provide stable estimates of the means. The SAV category contains only 32 observations and therefore the l i k e l i h o o d of obtaining reasonable estimates of the means for t h i s category i s remote. The STV category con-tained the l a r g e s t number of observations f o r a l l subjects and for the females; t h i s context was generally c l o s e r to the grand mean for a l l the variables than were the other object cate-gories. We do not know the exact number of cases needed i n order to give a stable picture of what i s occurring i n each of the categories. This would require repeating the MCA and experi-menting with d i f f e r e n t numbers of observations; i t could give some in s i g h t into what i s occurring with respect to the object contexts. 112 3 . 3 3 . Intersubject v a r i a b i l i t y The MCA was performed using SUBJECT as a predictor for the variables mean F , RANGE, DUR and the indices R/D and mean F x D x R. The predicted curves f i t the actual data i n o most cases, i n d i c a t i n g that the additive model applied for t h i s predictor. From Figure 4 i t can be observed that the mean F Q of about one-half of the subjects was close to the grand mean. The re- , mainder of the subjects showed a larger deviation from the grand mean with 1 0 9 - M having the lowest mean F o and 1 1 4 - M having the highest F . In the case of the females, those subjects deviating from the grand mean ( 1 1 5 - F , 1 1 6 - F and 1 1 8 - F ) were only analyzed up to six months of age. Since mean F Q does not seem to change appreciably with age the differences are l i k e l y at-tr i b u t a b l e to small sample s i z e . In the case of the males, deviations from the grand mean cannot be explained wholly by low sample size since two of the subjects ( 1 0 5 - M and 109-M) involved r e l a t i v e l y large numbers of utterances. The v a r i a b i l i t y i n the males' F q i s l i k e l y due to i n d i v i d u a l p h y s i c a l or environmental differences. On v i s u a l inspection, the graph of DUR vs SUBJECT (Figure 4 ) exhibits a considerable amount of intersubject v a r i a b i l i t y which , i s not e n t i r e l y due to small sample s i z e . Despite the v a r i a b i l i t y , the values for a l l subjects were within 1 5 0 msec of the grand mean. Given the large standard deviations observed f o r DUR ( 5 4 0 msec for females, and 4 7 5 msec for males), the data appear 113 uniform. Subject 104-F exhibited the shortest average DUR, while 201-M exhibited the longest. The graph of RANGE vs SUBJECT evinces rather less v a r i a b i l i t y than that for DUR ju s t described. Those females deviating from the grand mean (115-F and 118-F) were only analyzed up to six months. The exceptional cases for the males, which again cannot be t o t a l l y ascribed to low sample s i z e , include 103-M who ex-hi b i t e d the lowest average RANGE for a l l subjects, and 114-M who exhibited the highest average RANGE for a l l subjects. The graphs of R/D and mean F q x D x R (Figure 7) also ex-h i b i t considerable intersubject v a r i a b i l i t y . In the graph of R/D those subjects who exhibited values somewhat lower than the mean tended to be males, while those subjects having large excursions above the mean were females. No such sex trend was observed i n the mean F x D x R vs SUBJECT graph. Since both indices are o — based on the dependent variables described e a r l i e r , those sub-je c t s who tended to be ' o u t l i e r s ' were often the same subjects whose index values varied condiserably from the means for R/D and mean F x D x R. o 3.4 Intonation contour configurations The configurations of the various intonation contours i n three d i f f e r e n t age categories are shown i n Figure 8. Since mean F was found to remain stable across contexts, the means o for each variable were calculated i r r e s p e c t i v e of context. In general, the changes of BEGIN, FMP, SMP, END and RANGE with time 114 are minimal. Occasional large f l u c t u a t i o n s of DUR with age are noted but these reach s i g n i f i c a n e (at the 1% level) only f o r the RF, F and RF'R contours. A l l contours do, however, show an i n -crease i n DUR with age. Insert Figure 8 about here. The L utterances are t y p i c a l l y the shortest utterances, having an average DUR of about 300 msec. By operational d e f i -n i t i o n mean F does not fluctuate and therefore RANGE i s zero o (± 5 Hz c f . 2 .35) . The R and F utterances average approximately 4 25 msec i n length and have an average RANGE of about 68 Hz. -In terms of numerical values of mean F Q the two contours are mirror images: BEGIN of the R and END of the F are approxi-mately equal, as are END of the R and BEGIN of the F. The RF and FR utterances have an average DUR of about 68 0 msec and an average RANGE of aobut 100 Hz. RFR and FRF have the longest DUR (985 msec) and the largest RANGE (118 Hz) of a l l of the contours. 3.5. Results of Multiva r i a t e Nominal Scale Analysis 3.51. Intonation contour d i s t r i b u t i o n s 3.511. D i s t r i b u t i o n of contour by age Figure 9 shows the d i s t r i b u t i o n of the intonation contours by age i n ten i n t e r v a l s of f i v e weeks each. I t can be seen that only the d i s t r i b u t i o n of RF contours changes appreciably with age, and that t h i s change i s occurring i n a p o s i t i v e d i r e c t i o n 115 DURATION (msec) FIGURE 8. Contours and t h e i r development status i n three age categories for a l l subjects. 116 (40% at 5 weeks to 55% at one year). On the average, RF contours account for approximately 4 3% of the data, followed by the F and FRF contours which each account for about 13% of the data; RFR, R, FR and L account for 11%, 10%, 7% and 2.5% res p e c t i v e l y . Insert Figure 9 about here. The d i s t r i b u t i o n of the RFR contour, observably peaks at 21-25 weeks and 36-40 weeks, while the d i s t r i b u t i o n of the FRF contour peaks at 16-20 weeks, 26-30 weeks, and 46-50 weeks. The variable DUR and the mean F Q x D x R index were observed to peak at 26-30 weeks, 36-40 weeks and 46-50 weeks. Part of t h i s peaking behaviour may then be a r e s u l t of the c h i l d ' s production of a larger proportion of the RFR and FRF contours which charac-t e r i s t i c a l l y e x h i b i t longer durations than the other intonation contours. 3.512. D i s t r i b u t i o n of contour by subject and by sex It i s evident i s Figure 10 that the d i s t r i b u t i o n s of the d i f f e r e n t intonation contours are r e l a t i v e l y uniform across sub-j e c t s . The RF contour always accounts for the largest proportion of the utterances, while the L contour occurs the l e a s t often. The subjects who were analyzed only up to six months tend to show a larger proportion of the RFR and FRF contours. This trend may be due to the larger proportion of 2MP contours observed at six months. I t could also be an a r t i f a c t of small sample s i z e . The 117 01 L. RISE-FALL N =4845 j i_ FALL-RISE N =844 60 " 40 -20 -0 RISE N = 1119 FALL N =1490 60 p 60 r RISE-FALL-RISE N = 1278 0 I i i 1 1 LEVEL N =280 FALL-RISE-FALL N =1512 J L. J I I 1 7 13 18 23 28 33 38 43 48 53 AGE (MIDPOINTS OF 5-WK INTERVALS) 7 13 18 23 28 33 38 43 48 53 AGE (MIDPOINTS OF 5-WK INTERVALS) FIGURE 9. Developmental trend of frequency of each contour for a l l subjects. 118 data for 108-M are included, from which i t w i l l be noted that the shape of the d i s t r i b u t i o n of contours f o r t h i s subject de-viates from that of the majority of the subjects. Insert Figure 10 about here. When the data are grouped according to the sex of the sub-j e c t (Figure 11), the d i s t r i b u t i o n s of contour for males and females are found to be the same: The shape of the two d i s t r i -butions i s e s s e n t i a l l y s i m i l a r to that observed for the i n d i -vidual subjects, and for a l l subjects. Insert Figure 11 about here. 3 . 5 2 . Context d i s t r i b u t i o n s 3 . 5 2 1 . D i s t r i b u t i o n of context by age Figure 12 shows the d i s t r i b u t i o n s of the various contexts over the f i r s t year of l i f e . The S context, although f l u c t u a t i n g quite dramatically, exhibits an o v e r a l l increase with age, with peaks i n frequency at 1 6 - 2 5 weeks and 3 6 - 4 0 weeks. Of i n t e r e s t , the SM category shows a complementary decrease with age, but shows an increase near the end of the f i r s t year. While the d i s t r i b u t i o n i n the SOP category appears moderately random i n 119 C O N T O U R FIGURE 10. Percentage d i s t r i b u t i o n of contour frequency for each-subject and for a l l subjects. 120 FEMALES N = 4540 MALES N =6828 60 r 40 h 20 h RF FR R F L RFR FRF CONTOUR RF FR R F L RFR FRF CONTOUR % S SM SOP SV SAV STV SATV CONTEXT SM SOP SV SAV STV SATV CONTEXT FIGURE 11. Percentage d i s t r i b u t i o n of vocal i z a t i o n s by contour and context for females and males. 121 nature, a few i n t e r e s t i n g trends are apparent i n the object categories. Insert Figure 12 about here. The SV category i s shown to occur more frequently at 11^15 weeks and 41-45 weeks. Between these two peaks the graph remains at a r e l a t i v e l y low l e v e l , i n d i c a t i n g few utterances i n the SV context at other age l e v e l s . During the f i r s t months of l i f e the SV category consisted l a r g e l y of utterances produced i n the context of c r i b mobiles which many of the c h i l d r e n possessed. Since the i n i t i a l taping sessions were often c a r r i e d out with the c h i l d i n i t s c r i b , those children who had c r i b mobiles tended to v o c a l l y express great i n t e r e s t i n these toys and therefore the majority of the utterances produced were categorized as SO. It can also be noted that the SATV category exhibited a larger percentage of utterances at the younger age l e v e l s . This would be due to the large numbers of utterances produced i n the context of c r i b toys such as r a t t l e s , squeakers, and noisemaker mobiles (cf. Appendix I) which were not only v i s u a l l y but a u d i t o r i l y i n t e r e s t i n g . i As the infants became older and more a c t i v e , they were less l i k e l y to be r e s t r i c t e d to t h e i r c r i b s and more l i k e l y to be playing with items such as stuffed toys, blocks and stacking rings. This accounts for the higher percentage of STV utterances 122 60 h 40 20 0 60 40 20 FIGURE 12. SAV N= 32 SATV N =665 STV N =884 7 13 18 2 3 2 8 33 38 43 48 53 AGE (MIDPOINTS OF 5-WK INTERVALS) 13 18 23 28 33 38 43 48 53 AGE (MIDPOINTS OF 5-WK INTERVALS) Developmental trend of frequency of each context for a l l subjects. 123 at the age l e v e l s between 26 and 40 weeks, where the SV, SATV and SAV categories show a low frequency of occurrence. The r e l a t i v e l y high incidence of the SV category at 41-45 weeks i s l i k e l y a r e f l e c t i o n of the c h i l d ' s i n t e r e s t i n learning about his/her environment. Many of these l a t e r sessions included sequences of the c h i l d gesturing or somehow expressing i n t e r e s t i n a d i s t a n t object, and the mother naming or describing that object. For at lea s t one subject (102-F) t h i s a c t i v i t y became a game. The objects referred to were included i n the SV category because they were not auditory and the c h i l d generally did not touch them. Also included i n t h i s category were utterances pro-duced i n the context of the microphone, an object which proved highly i n t r i g u i n g to many of the ch i l d r e n . Utterances produced by the c h i l d i n response to seeing his/her r e f l e c t i o n i n glass or a mirror were also c l a s s i f i e d as SV. 3.522. D i s t r i b u t i o n of context by sex The d i s t r i b u t i o n s of context according to sex (Figure 11) are v i r t u a l l y i d e n t i c a l i n a l l but the SM and STV categories. The males e x h i b i t a much higher percentage of utterances i n the SM category than do the females, while the females e x h i b i t a s l i g h t l y higher percentage of utterances i n the STV category than the males. I t appears that the females' lower percentage , of utterances i n the SM context i s r e f l e c t e d by a higher per-centage i n the STV category, while the reverse i s true for the males. 124 3.53. D i s t r i b u t i o n of contour by context Subdividing the data according to context r e s u l t s i n d i s -t r i b u t i o n s of the intonation contours that are s i m i l a r i n shape to those of SEX vs CONTOUR and SUBJECT vs CONTOUR. A few s l i g h t differences among the contexts are noted and these differences become s l i g h t l y more v i s i b l e when graphs of percent d i s t r i b u t i o n vs CONTEXT are produced f o r the seven contours (see Figure 13). Insert Figure 13 about here. While the frequencies remain much the same across contexts, de t a i l e d inspection of the d i s t r i b u t i o n s reveals differences s u f f i c i e n t to warrant a c l a s s i f i c a t i o n on the basis of contour expectancy. Although s t a t i s t i c a l evaluation finds that only the contour d i s t r i b u t i o n s of the SAV, STV and SATV categories d i f f e r s i g n i f i c a n t l y from the mean, examination of r e l a t i v e l y substantial deviations from the mean (as an index of d i s t r i b u t i o n a l anomaly) indicates that each context may be described by a unique con-s t e l l a t i o n of contours, i n terms of t h e i r greatest deviations (both p o s i t i v e and/or negative). Any p r e d i c t i v e power achieved should not be overrated, however, since some of i t may be due to i a n a l y t i c a r t i f a c t s (such as contextual categorization procedures). In the following l i s t , and i n order of magnitude, reference i s made ex c l u s i v e l y to contours whose frequency i s su b s t a n t i a l l y above (positive) or below (negative) the mean f o r a given context. 125 RISE-FALL FALL-RISE RISE N =1119 FALL N = 1490 J L. _l U 60 r 60-40 RISE-FALL-RISE N = 1278 -o— J I 1 L LEVEL N =280 —o i FALL-RISE-FALL N =1512 J L J L S SM SOP SV SAV STV SATV CONTEXT S SM SOP SV SAV STV SATV CONTEXT FIGURE 13. Percentage d i s t r i b u t i o n of contours by context for a l l subjects. 126 CONTEXT CONTOUR S SM SOP SV SAV STV SATV Po s i t i v e FR, R RF FRF, F F RF, L RF FR, R, F, L Negative RF FR, R R, RFR RF FR, F FR, R, F RF, FRF I t i s i n t e r e s t i n g to note that the d i s t r i b u t i o n s of contour i n the S_ and SM contexts are complementary when examined on such an index. By the same token, S_ and SATV ex h i b i t v i r t u a l l y the same patterning, a l b e i t with more v a r i a t i o n i n the l a t t e r , with ( r e l a t i v e l y speaking) most vo c a l i z a t i o n s r i s i n g i n t h e i r terminal portion. In a l l other cases, f a l l i n g contours predominate on the po s i t i v e end of the scale. Further reseach involving a more uniform sample of utterances i s needed i n order to determine whether an index, such as the one described, can be used to describe various contexts of v o c a l i z a t i o n more vi a b l y . CHAPTER 4 Discussion 4.1. Review of the present r e s u l t s i n r e l a t i o n to theory and  previous research As noted i n the l i t e r a t u r e review, very l i t t l e research has been c a r r i e d out on infant non-cry v o c a l i z a t i o n s . Consequently, i t i s d i f f i c u l t , but not impossible, to assess our r e s u l t s i n the l i g h t of past research. We found that the mean P Q remains f a i r l y stable over the f i r s t year, averaging about 355 Hz. A recent study of infant crying v o c a l i z a t i o n s (Prescott, 1975) f a i l e d to show any con-s i s t e n t developmental change i n F q from b i r t h to nine months; FQ values of 385 Hz (0-10 days) and 415 Hz (6-9 months) were c i t e d . These values are higher than those reported i n the pres-ent study because of the disparate nature of the utterances i n -volved. Sheppard and Lane (1968) found that the FQ of t h e i r two subjects decreased i n i t i a l l y (up to 21 days) and then increased (by 45 days), whereupon i t s t a b i l i z e d u n t i l 5 months of age when the study was terminated. Both cry and non-cry utterances were examined i n that study, with the consequence that the values of F Q c i t e d are 50-100 Hz higher than those found i n the present study. Sheppard and Lane's r e s u l t s also take into account the f i r s t few weeks of l i f e , a period which was not examined here. In the Sheppard and Lane study, the single male subject's F O was c o n s i s t e n t l y about 25-35 Hz higher than the female's F . 127 128 The reverse was found to be true i n the present study: the mean F Q of the females was observed to be 25 ± 20 Hz higher than that of the males. This d i s p a r i t y may well be due to Sheppard and Lane's small subject sample; intersubject v a r i a b i l i t y i n our sample shows i n d i v i d u a l trends of s i m i l a r proportions. However, i n view of what i s known of the anatomy and physiology of the infant's vocal t r a c t , one would not expect to observe sex d i f f e r -ences at such an early age. One would expect to see a s l i g h t drop i n F Q over the f i r s t year, due to the lengthening of the vocal f o l d s . Such a decrease was not immediately apparent i n the data. An increase i n length of the vocal folds may be counterbalanced by other e f f e c t s , such as increased muscle con-t r o l over laryngeal a c t i v i t y . I t i s equally possible that cer-t a i n psychological variables are operating that r e s u l t i n the observed sex differences and perhaps obscure the changes that one might expect to occur as a r e s u l t of p h y s i o l o g i c a l changes i n the larynx. Moss (1967) found that mothers of females were more l i k e l y to imitate t h e i r infants than were mothers of males; the most l i k e l y ( a l b e i t unspecified) parameter i n t h i s regard would be F -mimicry. This intimates that mothers of female i n -o J fants may employ a s l i g h t l y higher-pitched voice when speaking to t h e i r infants which the i n f a n t would, i n turn, imitate. Lewis and Freedle (1973) noted that mothers responded to i n f a n t -i n i t i a t e d v o c a l i z a t i o n s more often with male infants than with female infants (except by means of vocal i n t e r a c t i o n ) . Infant v o c a l i z a t i o n i n response to maternal behaviour was more l i k e l y for females than males. If these observations are accurate, then i t would appear that more vocal i n t e r a c t i o n takes place between 129 female infants and t h e i r mothers than between male infants and t h e i r mothers. This could account for the precocity of the speech and language development of female childr e n which has often been c i t e d i n the l i t e r a t u r e . The project under which the present research was c a r r i e d out i s c u r r e n t l y undertaking .an i n -tensive i n v e s t i g a t i o n of t h i s purported phenomenon. A drop i n the females' mean F Q of 15 Hz can be observed at 41-45 weeks. This drop may be related to p h y s i o l o g i c a l changes, but i t i s immediately followed by a mean increase of 15 Hz. For the males i n our study, the F Q remains r e l a t i v e l y stable u n t i l 30 weeks, when i t begins to decrease; an o v e r a l l drop of 35 Hz i s observed by the end of the f i r s t year. This decrease may be mostly a t t r i b u t a b l e to p h y s i o l o g i c a l changes, but i t may have a psychological component inasmuch as the male in f a n t may be low-ering his p i t c h because of i m i t a t i o n of, or i d e n t i f i c a t i o n with the father, towards the end of the f i r s t year. Such behaviour has been observed with a 1.0-month-old male infant (Lieberman, 1967). In the present study, DUR was found to increase from approxi-mately 400 msec to 700 msec over the f i r s t year. Since the f i r s t age i n t e r v a l encompassed measurements from 4-10 weeks, the be-ginning estimate of DUR may be s l i g h t l y high. Graphs of DUR vs AGE for each subject revealed that DUR was i n i t i a l l y about 250 msec, and therefore increased about 450-500 msec from b i r t h to one year. Our r e s u l t s at the e a r l i e r age l e v e l s are s i m i l a r to those obtained for the duration of non-cry vocalizations by Murai (400 msec) and Ringwall, Reese and Markel (350 msec). 130 Nakazima (1962) reported a more exaggerated duration (600-800 msec) for one-month-old subjects. In the Sheppard and Lane (1968) study, the arithmetic mean of duration was about 550 msec, which i s comparable to the r e s u l t s reported here, except that Sheppard and Lane included c r i e s i n t h e i r study. They also re-4. ported geometric mean durations, but t h i s was not calculated i n the present i n v e s t i g a t i o n , since no v i a b l e meaning can be ascribed to such a c a l c u l a t i o n . Prescott (1975) measured the durations of c r i e s ; the values c i t e d i n that study are much higher than those obtained here and were noted to increase with age. S i g n i f i c a n t differences i n that study were found between age l e v e l s (0-10 days, and 6-9 months), and between subjects at the e a r l i e r age l e v e l s only; v a r i a b i l i t y was greater at the e a r l i e r age l e v e l . Our r e s u l t s indicate that the v a r i a b i l i t y (qua standard deviation) i n duration increased as the duration increased. In the present study, within-utterance range was found to increase with age. I t was noted that while the RANGE for f e -males increased consistently with,age, that for males increased u n t i l about 40 weeks and then decreased. Studies such as those of Prescott (1975) and Sheppard and Lane (1968) have examined within-utterance v a r i a b i l i t y , but do not define t h e i r terms. Prescott (1975) noted that within-utterance F Q v a r i a b i l i t y was consistently greater at the advanced age l e v e l (6-9 months) for four of the subjects, than i t was from b i r t h to 10 days. Sheppard and Lane (1968) computed c o e f f i c i e n t s of v a r i a t i o n i n 131 fundamental frequency, both between and within utterances, and found no change with age. Prescott (1975) also tested but d i d not bear out the hy-pothesis that within-utterance F Q v a r i a b i l i t y covaried with duration. RANGE and DUR were thought to covary i n the present study, but graphs of RANGE vs DUR, and R/D vs AGE (cf. 3.31) did not evince any consistent r e l a t i o n s h i p s between the two varia b l e s . As mentioned e a r l i e r , RF contours accounted for about 43% of the data. Considered together, the three contours which f a l l i n t h e i r terminal portions, RF, F and FRF, account for about 70% of the data. These r e s u l t s lend credence to Lieberman's (1967) hypothesis concerning the f a l l of F Q at the end of an utterance. The o v e r a l l percentage d i s t r i b u t i o n s of the contours agree, to a c e r t a i n extent, with those of Wasz-Hockert et a l . (1968) for pleasure c r i e s . The percentage d i s t r i b u t i o n s of the F, R and FR contours are very s i m i l a r . A larger difference i s noted for RF which accounted for 31% of the Wasz-Hfickert data; RFR and FRF contours were not described i n that study. The main d i s -crepancy occurs i n the d i s t r i b u t i o n of L contours which accounted 'for 2.5% of the present study, as opposed to 46% i n the Wasz-Hockert study. The difference l i e s i n the operational d e f i n i t i o n of L used i n the two studies. For the purposes of the present study, a l e v e l utterance exhibited l i t t l e or no change i n F Q , whereas i n the Wasz-Hockert study a much larger deviation i n F^ 132 was required. The use of the L contour i n the present study implies that considerable control i s being exercised over the vocal apparatus; since muscular control i s not f u l l y developed i n the infant, one would not expect to see many L utterances. It i s more d i f f i c u l t to compare the present r e s u l t s with those of Tonkova-Yampol'skaya (1969). Her study involved a q u a l i t a t i v e d e s c r i p t i o n of the intonation contours which was more concerned with the 'meaning' attached to the contour. One s i m i l a r i t y i s evident between the R of t h i s study and the .infant intonation of expressive calm cooing i n Tonkova-Yampol'skaya's investi g a t i o n which would be described as R i n terms of our study. The incidence of t h i s pattern i s found to increase at nine months i n both studies. The peaking behaviour of the graphs, which i s commonly ob-served at 4-6, 9, and (to a lesser degree) 11 months, i s remini-scent of Bever's (1961) findings upon reanalysis of Irwin and Chen's data concerning phonemic development i n i n f a n t s . VJhile Bever interpreted the peaks as d i s c o n t i n u i t i e s (as per the maturational approach), i t would appear that t h i s i s not neces-s a r i l y the case. I f concomitant peaks are occurring when both segmental and suprasegmental phenomena are considered, i t would seem that t h i s would demonstrate a continuity i n the system which has otherwise been ignored. As suggested by Bever (1961) and Tonkova-Yampol'skaya (19 69), t h i s peaking behaviour may be cor-related with the advent of c o r t i c a l control and organization of vocal output. 133 Moreover, descent and growth of the larynx, as well as the concomitant readjustment of the supralaryngeal vocal t r a c t and i t s growth may be of import here (cf. Wind, 1970; Kirchner, 1970). I t was noted e a r l i e r that the adult female r a t i o of vocal f o l d length to the diameter of the lumen of the trachea ( viz . 1 : 1.5) i s reached by nine months of age. This coincides with the most commonly observed nine-month peak. I t i s also around t h i s time that more precise imitation of both segmental and suprasegmental phenomena,are noted and 'role-playing' or i m i t a t i o n of adult models occurs (Lewis, 1951; Lieberman, 1967; Piaget and Inhelder, 1966). In general, the d i s t r i b u t i o n s of CONTEXT vs AGE r e f l e c t e d the subjects' i n t e r e s t s i n t h e i r surroundings, and to some ex-tent, a r t i f a c t s i n our sampling procedures. The d i s t r i b u t i o n s of CONTEXT vs SEX did not indicate any c l e a r - c u t preferences for ce r t a i n types of objects by one sex or the other. I t was not found, for example, that males were more v i s u a l l y oriented and females were more a u d i t o r i l y oriented, as has been suggested i n the l i t e r a t u r e . There was a higher percentage of STV utterances for. females than males which balanced the lack of utterances i n the SM category. The higher percentage of SM utterances for the males i s a more curious fi n d i n g , i n view of the r e s u l t s of Moss (1967) and Lewis and Freedle (1973). Perhaps i f the mothers of females vocalize more often to t h e i r i n f a n t s , the females have less of a chance to vocalize i n turn; or i f the females do vo-c a l i z e , there could be some overlap with the mother's utterance which would mean that the c h i l d ' s utterances could not be 134 analyzed spectrographically. A l t e r n a t i v e l y , the finding may be correlated with Lewis and Freedle's (1973) observation that the female infants tended to be more r e s t r i c t e d than the males i n terms of muscular a c t i v i t y . Perhaps t h i s r e s t r i c t i o n extends to vocal a c t i v i t y as well. 2 The r e s u l t s of the Hotelling's T tests indicate that d i f -f e r e n t i a l v o c a l i z a t i o n i s not occurring with respect to the v a r i -ables examined. The MCA r e s u l t s also indicate l i t t l e d i fference 'between contexts. The s l i g h t differences that are observable are, generally not consistent from one context to the next. I t i s possible that other variables not examined — such as amplitude, harmonic structure, or temporal factors such as the time at which a change ( i . e . middle-point) occurs i n an utterance — may be of importance i n d i f f e r e n t i a t i n g environmental events. In addition, a more s p e c i f i c s i t u a t i o n a l analysis regarding the antecedent and subsequent events with respect to infant vocal-i z a t i o n would e l i c i t some valuable information. I t i s not known, for example, what reinforces an act of d i f f e r e n t i a l v o c a l i z a t i o n , i f and when such an act does occur. Again, research into t h i s problem i s currently i n progress within the framework of the more comprehensive project of which t h i s study i s a part. An inspection of the sequences of utterances i n the data reveals that on occasion, infants repeat s i m i l a r intonation patterns i n successive utterances; such behaviour i s also known to occur at the segmental l e v e l . I t i s not known at t h i s time whether t h i s type of a c t i v i t y takes place i n some situ a t i o n s more than i n others. There i s some evidence i n the r e s u l t s of 135 CONTOUR vs CONTEXT to suggest that the infants may u t i l i z e con-tour v o l i t i o n a l l y (rather than the i n d i v i d u a l parameters of F , DUR and RANGE) to indicate the s i t u a t i o n of v o c a l i z a t i o n . If th i s i s the case, then non-significant r e s u l t s from a s t a t i s t i c a l 2 t e s t such as the Hotelling's T would be expected, as found. 4.2. Limitations of the present i n v e s t i g a t i o n 4.21. Sample size A major problem encountered i n t h i s experiment was that of sample s i z e . The SO categories tended to have fewer utterances than the S_ and the i n c i d e n t a l l y examined SM and SOP categories. The accuracy of our res u l t s depends on the s t a b i l i t y of the mean values calculated. Furthermore, the MCA predicted model i s of no use when there are only a few observations i n each c e l l . Consequently, a large number of utterances are needed, or f a i l i n g that, each avai l a b l e utterance must be t y p i c a l of a p a r t i c u l a r category. Analysis of the utterances according to intonation contour was often impossible because most s t a t i s t i c a l procedures require at l e a s t f i v e utterances per category, and t h i s condition was often not s a t i s i f i e d by our corpus of data. 4.22. C l a s s i f i c a t i o n of utterances according to context Some d i f f i c u l t i e s were encountered i n the i n i t i a l , rather ad hoc c l a s s i f i c a t i o n of the i n f a n t s 1 utterances i n terms of the contexts i n which they occurred. Without a video tape and an ongoing des c r i p t i o n of the events occurring during the recording sessions, we cannot be ce r t a i n of the precise events that resulted 136 i n a given infant's v o c a l i z a t i o n . Despite such problems, we believe that the c l a s s i f i c a t i o n scheme used was consistent enough that c e r t a i n behaviours, i f they occurred, could be examined systematically. Due to the problems with sample s i z e , i t was necessary to group the objects into gross categories. In s e l e c t i n g the categories and assigning objects to these categories we have necessarily imposed an adult judgement as to which a t t r i b u t e s of the objects the infants would f i n d most s a l i e n t . We cannot be c e r t a i n that the four designated object categories were neces-s a r i l y c o rrect or appropriate i n terms of the infant's i n t e r e s t s / motivations. Categories such as STV c o n s i s t of a potpouri of objects which should probably have been subcategorized, were i t not for constraints on the a n a l y t i c procedures employed. Ideally, a uniform sample of objects should have been used for a l l subjects. In t h i s manner more valuable intersubject comparisons could have been made. This was not of major import i n the c o l l e c t i o n of the data and therefore remains a desideratum for future study. 4.23. Measurement Due to the laborious and time-consuming work involved i n spectrographic analysis and measurement, we were forced to l i m i t our measurements of fundamental frequency (and necessarily i n t o -nation contour) to a maximum of four points per utterance. Measurements at more points would have given a more accurate 137 p i c t u r e o f t h e c o n t o u r ; however such an u n d e r t a k i n g a w a i t s more s o p h i s t i c a t e d i n s t r u m e n t a t i o n f o r use w i t h r e c o r d i n g s o b t a i n e d i n a n a t u r a l ( i . e . , n o n - l a b o r a t o r y ) s e t t i n g . 4.3. I m p l i c a t i o n s f o r t h e o r y and f u t u r e r e s e a r c h The f i n d i n g s o f t h i s s t u d y answer a few o f t h e q u e s t i o n s c o n c e r n i n g p r o s o d i c development and p r o s o d i c c o n t r a s t i v i t y i n t h e f i r s t y e a r o f l i f e , b u t as e x p e c t e d , r a i s e even more q u e s t i o n s . D e v e l o p m e n t a l o b s e r v a t i o n s o f t h e d i f f e r e n t a c o u s t i c p a r a m e t e r s (F , RANGE, DUR and CONTOUR) i n d i c a t e t h e i r complex i n t e r d e p e n d e n t n a t u r e . A s a t i s f a c t o r y e x p l a n a t i o n o f t h e be-h a v i o u r o f t h e s e p a r a m e t e r s i n p h y s i o l o g i c a l terms i s n o t pos-s i b l e , g i v e n t h e l a c k o f i n f o r m a t i o n c o n c e r n i n g t h e development o f r e s p i r a t o r y f u n c t i o n and t h e a c t i o n o f t h e l a r y n g e a l m u s c l e s i n young i n f a n t s . There i s s t i l l no adequate d e s c r i p t i o n o f the i n f a n t ' s p s y c h o l o g i c a l development d u r i n g t h e f i r s t y e a r , n or i s enough known o f t h e i n f a n t ' s p e r c e p t i o n o f h i s / h e r v o c a l o u t p u t and how t h i s r e l a t e s t o speech development. Moreover, how t h e s e p a r a m e t e r s a r e c o r t i c a l l y c o n t r o l l e d r emains a m y s t e r y . E a r l i e r , remarks were made c o n c e r n i n g t h e p e a k i n g b e h a v i o u r o b s e r v e d i n t h i s s t u d y and t h e c o i n c i d e n t peaks o b s e r v e d when segmental b e h a v i o u r has been s t u d i e d . T h i s seems t o i n d i c a t e t h e r e l a t i v e i n s e p a r a b i l i t y o f segmental, and s u p r a s e g m e n t a l phenomena i n e a r l y l i f e . S i n c e s u p r a s e g m e n t a l development i s known t o be c o n t i n u o u s w i t h l a t e r speech development, b a b b l i n g and e x p e r i -m e n t a t i o n a t t h e segmental l e v e l must a l s o be r e c o g n i z e d as b e i n g o f i m p o r t and i n c o n t i n u i t y w i t h l a t e r speech development. 138 The p r e s e n t s t u d y a l s o shows t h e i m p o r t a n c e o f u s i n g c o n -t e x t u a l i n f o r m a t i o n i n a n y s t u d y o f s p e e c h a n d l a n g u a g e d e v e l o p -m ent. F u t u r e r e s e a r c h s h o u l d be d e s i g n e d t o o b t a i n m ore i n f o r -m a t i o n a l o n g t h e s e l i n e s . The i n s i g h t t h u s a c h i e v e d c o u l d be u s e d i n d e v i s i n g m o d e l s o f s p e e c h a n d l a n g u a g e d e v e l o p m e n t w h i c h c o u l d a i d i n a f u r t h e r u n d e r s t a n d i n g o f t h e c o m p l e x p r o c e s s e s i n v o l v e d . 4 . 4 . Summary I n t o n a t i o n p a t t e r n s o f n o n - c r y v o c a l i z a t i o n s o f i n f a n t s o c c u r r i n g i n two b a s i c s i t u a t i o n s ( i . e . , i n f a n t a l o n e and i n f a n t i n t h e c o n t e x t o f v a r i o u s o b j e c t s ) w e r e a n a l y z e d s p e c t r o g r a p h i -c a l l y f o r f u n d a m e n t a l f r e q u e n c y , w i t h i n - u t t e r a n c e r a n g e , d u r a t i o n a n d c o n t o u r . E a c h v a r i a b l e was e x a m i n e d l o n g i t u d i n a l l y a n d i n d i f f e r e n t c o n t e x t s . A number o f age t r e n d s w e r e e v i d e n t . D u r a t i o n a n d w i t h i n -u t t e r a n c e r a n g e i n c r e a s e d w i t h a g e , w h e r e a s f u n d a m e n t a l f r e q u e n c y r e m a i n e d r e l a t i v e l y s t a b l e o v e r t h e f i r s t y e a r . F e m a l e s e x h i b -i t e d a h i g h e r F Q t h a n t h e m a l e s a t a l l age l e v e l s e x a m i n e d . P e a k v a l u e s o f t h e v a r i a b l e s w e r e commonly o b s e r v e d a t 4 - 6 , 9 , a n d ( t o a l e s s e r d e g r e e ) 11 m o n t h s . The RF i n t o n a t i o n c o n t o u r i n -c r e a s e d i n f r e q u e n c y o f o c c u r r e n c e d u r i n g t h e f i r s t y e a r , w h i l e t h e o t h e r c o n t o u r s e x a m i n e d d e m o n s t r a t e d l i t t l e c h a n g e . C o n t r a s t s o f u t t e r a n c e s o c c u r r i n g i n d i f f e r e n t c a t e g o r i e s r e v e a l e d e s s e n t i a l l y no d i f f e r e n c e b e t w e e n c o n t e x t s f o r t h e v a r i a b l e s s t u d i e d . E x a m i n a t i o n o f t h e d i s t r i b u t i o n s o f t h e 139 d i f f e r e n t intonation contours for each context indicated that the infants could be manipulating contour d i f f e r e n t i a l l y i n a given context. In sum, the findings of t h i s study document a very r e a l , a l b e i t circumscribed, capacity of the part of the infant for voc a l l y d i f f e r e n t i a t i n g environmental events, one of the basic components i n the development of communicative competence. In general i t i s held that there exists s u f f i c i e n t evidence to r e -fute the parochial view that l i n g u i s t i c a c q u i s i t i o n can only be relevantly discussed when the c h i l d ' s segmental phonetic output begins to resemble that of the adult standard; i n other words, we support the hypothesis of continuity from babbling to speech. 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Where multiple entries appear under LOCATION and N, read the f i r s t entry i n each column, then the second entry i n each column, and so on. SUBJECT MNEMONIC ID LOCATION (in weeks) N DESCRIPTION 101- F MOBILE 14 TESSIE 16 SWAN 18 TOYRINGS 47 TAMBOURI 27 BLANKET 18 BIB 22 MIRROR 47 102- F MOBILE 7 TOY 21 BLUEBEAR 27 SNOOPY 41 DOG 4 7 BLOCKS 54 BALL 47 RATTLE 24,25 CLINKS 18 14 V 7 TV stuffed t u r t l e 1 TV 1 TV stacking rings 4 ATV tambourine 5 TV 20 TV 1 V 77 V 1 TV 5 TV stuffed bear 15 TV stuffed dog 7 TV 6 TV 9 TV 1,1 ATV 1 ATV un i d e n t i f i e d 152 SUBJECT MNEMONIC ID LOCATION (in weeks) N DESCRIPTION 102-F 103-M 104-F 105-M 106-F MOBBELLS 19 2 ATV mobile with b e l l s MIKE 21 1 V microphone PAPERS 41 10 V newspapers PHOTO 45 6 V family photograph BOOKS 47,50 7, 6 V CANDLE 50 8 V KEYS 54 9 ATV SLIPPER 54 7 TV MOBILE 15 213 V BALL 28 5 TV RATTLE 28 •3 ATV BELLS 22 17 ATV MOBILE 16 16 .V PINKTEDD 7 29 ATV musical teddy bear SNOOPY 14,16,20 34, 3,6 TV stuffe d dog GREEFROG 20 50 TV s t u f f e d frog HAIRDOLL 24 41 TV hairy d o l l GRAYDOG 26 10 TV stuffe d dog GROUNHOG 26 15 TV groundhog RATTLE 9 65 ATV CLOWN 14 103 ATV j i n g l i n g clown PULLTOY 52 6 ATV EATINCUP 24,26 38, 25 TV baby's mug MIKE 16 50 V microphone BOOKS 23 6 V DUCK 53 9 TV toy duck TAPERECR 53 10 V tape recorder MIRROR 33 6 V BOTTLE 7,16 25, 3 TV PUPPY 24 13 TV toy dog BLOCKS 50 6 TV POPBEADS 54 7 TV p l a s t i c beads RINGTOSS 54 8 TV toy rings RATTMOBI 20 3 ATV r a t t l e mobile RATTBELL 15 3 ATV r a t t l e MUSICBOX 14 14 AV LION 15,18 1, 7 ATV squeaky toy YELORATT 28 16 ATV r a t t l e TOYMOUSE 50 15 ATV squeaky toy RATTLE 50 7 ATV POTS 44 8 TV kitchen pots BLANKET 54 9 TV 153 SUBJECT MNEMONIC LOCATION N DESCRIPTION ID (in weeks) 107-M BLOCKS 53 12 TV TOY 32 10 TV u n i d e n t i f i e d TOYRINGS 35 5 TV stacking rings RATTLES 10 4 ATV BELLS 13,24 3,7 ATV SQUDUCK 23,24 15,3 ATV squeaky duck 109-M TOYBOATS 32 9 TV BALL 35 8 TV JUMPROPE 44 12 TV TOYSUNID 18 4 ATV u n i d e n t i f i e d TELEPHON 32 6 ATV toy phone HAMMER 35 7 ATV squeaky toy WHISTLE 41 6 ATV MIKE 41 18 V microphone CHAIR 7 13 V MOTHRING 13 8 TV mother's rin g SHOE 24 5 TV JUDYHAIR 30 5 TV E's hair 110-M BLOCKS 38 15 TV BALLOON 48 5 TV MIKE 38,41 11,13 V microphone REFLECT 30 18 V r e f l e c t i o n of c h i l d 111-M MOBILE 12,32 12,10 V RAGDOLL 14,15,18,21/ 15,15,16,7 TV stu f f e d toy TEDDY 12,14 16,13 TV stu f f e d toy BLUBUNNY 14,15,18,28/16,15,16,10 TV stuffed toy ELEPHANT 18,21 15,7 TV stuffed toy PLUTODOG 28 15 TV RATTPIN 21 9 ATV r a t t l e RATTLE3 23 8 ATV r a t t l e MIKE 35 5 V microphone RADIO 24 7 AV WALPAPER 32 5 V wallpaper BOWL 40 12 TV 112-M TEDDBEAR 11 9 TV stuffed toy BALL 20 15 TV 113-M GREBUNNY 13 8 TV green bunny toy PANDBEAR 26 6 TV panda bear RATTLE 24 5 ATV KEYS 26 12 ATV HAT 26 5 TV 154 SUBJECT MNEMONIC ID LOCATION (in weeks) N DESCRIPTION 115-F POOH 22,24 5,15 TV teddy bear TAPERECR 20 6 V NECKLACE 19 6 TV 116-F MOBILE 22 7 V TEDDBEAR 18,22,26 15,12,7 TV teddy bear RABBIT 22 8 TV toy rabbit 117-M STUFFDOG 16 5 TV stuffed dog TEDDY 20 12 TV teddy bear MUSICBOXI 16 11 AV musicbox 118-F TEDDBEAR 15 15 TV teddy bear GUNK 19,23,24 15,9,9 TV stuffed toy DOLLY 23 8 TV d o l l STUFFDOG 24,26 9,10 TV stuffed dog RATTLE 8 5 ATV 108-M RATTLE 11,13,15, 43,13,19, ATV 18,21 139,64 APPENDIX B AVERAGED DATA FOR MULTIPLE CLASSIFICATION ANALYSIS Page F data for age and context 156 o ^ Duration data for age and context 157 Within-utterance range data f o r age and context 158 F , duration and range for each subject 159 R/D and mean F Q x D x R for age and context 160 R/D and mean F^ x D x R for each subject 161 155 156 F U N D A M E N T A L F R E Q U E N C Y ( M E A N / S . D . I N H Z ) A G E (WKS) F E M A L E S M A L E S C O M B I N E D 0 - 1 0 3 6 5 / 6 5 3 5 0 / 8 0 3 5 5 / 7 5 1 1 - 1 5 3 5 0 / 5 5 3 4 5 / 8 0 3 4 5 / 7 5 1 6 - 2 0 3 6 5 / 8 0 3 5 5 / 8 0 3 6 0 / 8 0 2 1 - 2 5 3 8 0 / 6 5 3 4 0 / 6 5 3 5 5 / 6 5 2 6 - 3 0 3 8 0 / 6 5 3 6 0 / 1 1 0 3 7 0 / 9 0 3 1 - 3 5 3 6 0 / 6 5 .' 3 5 0 / 8 0 3 5 0 / 7 5 3 6 - 4 0 3 7 0 / 7 0 3 4 0 / 4 5 3 6 0 / 6 0 4 1 - 4 5 3 5 5 / 6 0 3 3 0 / 7 0 3 4 0 / 7 0 4 6 - 5 0 3 7 0 / 7 0 3 3 0 / 5 5 3 5 0 / 6 5 5 1 - 6 0 3 7 0 / 6 0 3 2 5 / 6 0 3 4 5 / 6 5 C O N T E X T S 3 6 5 / 6 5 3 5 0 / 8 5 3 5 5 / 8 0 S M 3 7 5 / 7 0 3 4 5 / 7 0 3 5 5 / 7 0 S OP 3 8 0 / 7 0 3 5 5 / 9 0 3 7 0 / 8 5 S V 3 5 0 / 5 5 3 3 0 / 4 0 3 4 0 / 5 0 S A V 3 5 5 / 9 0 3 2 5 / 6 5 3 4 0 / 8 0 S T V 3 7 5 / 6 5 3 3 0 / 5 0 3 5 5 / 6 5 S A T V 3 3 5 / 6 0 1 3 4 5 / 8 0 3 4 0 / 7 5 T O T A L 3 7 0 / 7 0 3 4 5 / 8 0 3 5 5 / 7 5 157 D U R A T I O N ( M E A N / S . D . I N M S E C ) A G E (WKS) F E M A L E S M A L E S C O M B I N E D 0 - 1 0 3 7 5 / 3 1 0 4 3 0 / 3 3 0 4 0 5 / 3 2 0 1 1 - 1 5 4 8 0 / 3 8 0 6 1 0 / 4 2 5 5 7 5 / 4 1 5 1 6 - 2 0 6 3 0 / 5 3 5 7 2 5 / 4 8 0 6 9 5 / 5 0 5 2 1 - 2 5 6 9 5 / 6 2 0 8 0 5 / 5 6 0 7 6 0 / 5 9 0 2 6 - 3 0 7 7 5 / 5 4 0 6 7 0 / 4 1 0 7 2 5 / 4 8 0 3 1 - 3 5 7 0 5 / 5 0 5 6 9 0 / 4 7 0 7 0 0 / 4 8 5 3 6 - 4 0 9 0 0 / 6 8 5 8 1 5 / 5 1 0 8 6 5 / 6 2 0 4 1 - 4 5 7 6 0 / 5 2 0 6 9 5 / 4 6 5 7 2 5 / 4 9 0 4 6 - 5 0 7 5 0 / 5 7 0 7 5 5 / 5 1 5 7 5 5 / 5 4 5 5 1 - 6 0 6 4 5 / 4 5 0 6 0 5 / 3 7 5 6 2 5 / 4 1 5 C O N T E X T S 6 4 5 / 5 3 5 6 9 5 / 4 9 0 6 7 5 / 5 1 0 S M 6 3 0 / 5 3 0 6 4 0 / 4 7 5 6 3 5 / 4 9 5 S OP 6 2 0 / 4 7 0 7 0 5 / 4 9 0 6 6 5 / 4 8 5 S V 4 8 5 / 4 3 5 6 1 5 / 4 2 0 5 6 5 / 4 3 0 S A V 3 6 5 / 4 0 5 8 1 0 / 3 2 5 6 1 5 / 4 2 0 S T V 7 4 0 / 6 6 0 6 6 0 / 3 8 0 7 0 5 / 5 6 0 S A T V 4 8 5 / 4 3 5 7 3 0 / 5 2 0 6 2 5 / 5 0 0 T O T A L 6 3 5 / 5 4 0 6 7 5 / 4 7 5 6 6 0 / 5 0 0 158 W I T H I N - U T T E R A N C E R A N G E ( M E A N / S . D . I N H Z ) A G E ( W K S ) F E M A L E S M A L E S C O M B I N E D 0 - 1 0 8 0 / 7 5 8 5 / 7 0 8 5 / 7 5 1 1 - 1 5 8 5 / 6 5 .95 / 8 5 9 5 / 8 0 1 6 - 2 0 1 0 0 / 8 0 1 0 0 / 8 0 1 0 0 / 8 0 2 1 - 2 5 1 0 5 / 7 0 9 5 / 7 0 1 0 0 / 7 0 2 6 - 3 0 1 0 5 / 7 0 1 0 0 / 8 5 1 0 0 / 8 0 3 1 - 3 5 9 0 / 7 0 1 0 0 / 8 0 9 5 / 7 5 3 6 - 4 0 1 0 5 / 8 0 1 0 5 / 6 0 1 0 5 / 7 0 4 1 - 4 5 1 0 0 / 7 5 8 5 / 6 0 9 5 / 6 5 4 6 - 5 0 1 1 0 / 8 5 9 0 / 5 5 1 0 0 / 7 0 5 1 - 6 0 1 1 0 / 8 5 8 0 / 6 0 9 5 / 7 5 C O N T E X T • S 9 5 / 7 5 9 5 / 8 0 9 5 / 8 0 S M 1 0 0 / 7 5 1 0 0 / 7 0 1 0 0 / 7 5 S OP 1 1 0 / 7 5 1 1 0 / 1 0 0 1 1 0 / 9 0 S V 9 5 / 6 5 8 5 / 5 5 9 0 / 6 0 S A V 7 5 / 6 0 9 0 / 8 5 8 0 / 7 5 S T V 1 1 0 / 7 5 9 0 / 5 0 1 0 0 / 6 5 S A T V 7 5 / 7 5 8 0 / 6 5 8 0 / 7 0 T O T A L 9 5 / 7 5 9 5 / 7 5 9 5 / 7 5 159 FUNDAMENTAL MEAN / S, D. : FREQUENCY (Hz) SUBJECT 101-F 365 / 80 102-F 370 / 65 103-M 340 / 65 ,104-F 365 / 65 I05-M 395 / 105 106-F 360 / 60 107-M 330 / 50 108-M 360 / 90 109-M 305 / 75 110-M 345 / 50 111-M 325 / 65 112-M 345 / 55 113-M 335 / 50 114-M 410 / 95 115-F 405 / 75 116-F 340 / 45 117-M 370 / 70 118-F 400 / 60 201-M 365 / 40 TOTAL (WEIGHTED) 355 / 75 RANGE (Hz) DURATION (MSEC] 95 / 80 705 / 570 100 / 75 570 / 500 85 / 65 580 / 435 90 / 75 525 / 480 100 / 90 740 / 520 90 / 65 755 / 590 100 / 60 645 / 500 95 / 90 645 / 415 85 / 80 630 / 480 80 / 55 640 / 445 110 / 65 795 / 450 95 / 55 590 / 415 100 / 55 630 / 410 150 / 115 825 / 520 115 / 90 595 / 470 100 / 65 790 / 600 115 / 95 825 / 615 130 / 70 715 / 545 95 / 55 890 / 555 95 / 75 660 / 500 160 RANGE T DURATION ( x 10"1) Fn x RANGE x DURATION (x 10'7) AGE (WKS) 0-10 2.60 1.64 11 - 15 2.07 2.51 16 - 20 1.94 3.28 21 - 25 1.83 3.45 26 - 30 1.82 3.24 31 - 35 1.73 . 3.11 3.6 - 40 1.61 4.06 -41 - 45 1.69 2.83 46 - 50 1.87 3.04 51 - 60 1.89 2.64 CONTEXT S 1.89 3.02 S M 2.13 2.84 S OP 2.16 3.56 S V 2.14 2.06 S AV 2.62 2.15 STV 1.90 , 3.17 S ATV 1.73 2.34 TOTAL (WEIGHTED) 1.98 2.93 161 RANGE T DURATION ( x IP'1) Fn x RANGE x DURATION (x SUBJECT FEMALES MALES FEMALES MALES 101-F 1.90 3.25 102-F 2.50 2.67 103-M 1.89 2.15 104-F 2.33 2.36 1 0 5 - M 1.96 3.69 106-F 1.81 3.04 107-M 2.22 2.61 108-M 1.76 2.94 109-M 1.66 2.40 110-M 1.52 2.20 111-M 1.59 3.26 112-M 2.09 2.25 113-M 1.99 2.36 114-M 2.54 6.12 115-F 2.35 3.54 116-F 1.63 3.51 117-M 1.78 4.50 118-F 2.45 4.74 201-M 1.36 3.52 TOTAL 2.14 1.86 3.30 3.17 COMBINED (UNWEIGHTED) 1.96 3.22 COMBINED (WEIGHTED) 1.98 2.93 APPENDIX C DISTRIBUTIONAL DATA DERIVED FROM MULTIVARIATE NOMINAL SCALE ANALYSIS Page Percentage d i s t r i b u t i o n of contours by age, context and sex 163 Percentage d i s t r i b u t i o n of contours by subject 164 Percentage d i s t r i b u t i o n of contexts by age and sex 165 Percentage d i s t r i b u t i o n of contexts by subject 166 Percentage d i s t r i b u t i o n of contours and context by age.. 167 162 163 DISTRIBUTION (%) OF CONTOURS BY AGE, CONTEXT, AND SEX CONTOUR: N R - F F - R RISE FALL LEVEL R-F-R F-R-F AGE ( W K S ) 0 - 10 1518 40.0 7.9 14.6 17.9 3.9 7.1 8.6 11 - 15 2046 41.1 6.5 10.9 16.1 3.4 9.1 13.0 16 - 20 2498 38.3 8.3 9.2 12.2 2.6 13.4 16.1 21 - 25 2047 45.0 6.4 7.9 10.9 1.7 13.9 14.2 26 - 30 815 45.0 8.0 7.2 10.4 1.5 12.1 15.7 31 - 35 584 45.7 8.2 7.0 14.6 2.4 9.1 13.0 36 - 40 554 44;0 8.3 8.3 11.6 1.1 13.5 13.2 m - 45 531 45.4 9.6 11.7 11.7 1.5 9.8 10.4 46 - 50 450 49.6 7.1 8.0 8.7 1.8 11.3 13.6 51 - 60 325 54.2 3.7 12.6 7.7 1.2 10.8 9.8 CONTEXT • -S 5414 41.0 8.8 11.6 12.2 2.4 11.3 12.7 S M 3140 45.2 5.3 7.9 13.8 2.4 11.1 14.3 S OP 685 41.6 7.4 7.2 15.2 2.3 9.8 16.5 S V 548 39.6 7.1 9.7 19.0 2.6 10.4 11.7 S AV 32 46.9 3.1 9.4 9.4 6.3 12.5 12.5 S TV 884 54.6 2.8 5.8 9.3 0.9 12.9 13.7 S ATV 665 30.8 13.1 12.9 15.6 5.3 11.4 10.8 SEX FEMALE 4540 41.5 ' 7.8 11.2 14.3 2.5 10.6 12.1 MALE 6828 43.4 7.2 8.9 12.3 2.4 11.7 14.1 TOTAL 11368 42.6 7.4 9.8 13.1 2.5 11.2 13.3 164 DISTRIBUTION (%) OF CONTOURS BY SUBJECT lONTOUR: N R - F F - R RISE FALL LEVEL R-F-R F-R-F SUBJECT 101-F 744 39.7 9.7 15.5 17.1 3.0 7.7 7.5 102-F 920 51.5 4.3 10.7 14.2 1.4 7.1 10.8 103-M 1249 32.7 12.2 10.6 18.6 2.8 11.4 11.7 104-F 1298 33.4 11.3 13.3 16.4 3.2 11.5 10.9 105-M 684 43.4 6.9 9.6 12.1 2.6 13.2 12.1 106-F 808 41.8 5.7 10.6 12.7 4.0 11.0 14.1 107-M 792 53.3 3.5 6.9 11.2 2.4 9.7 12.9' 108-M 1053 30.3 11.1 17.7 12.5 5.6 11.4 11.4 109-M 661 50.7 5.1 12.9 12.3 2.4 9.4 7.3 110-M 415 41.4 8.9 8.9 11.1 1.2 11.1 17.3 111-M 730 59.3 3.3 1.6 7.7 0.5 12.2 15.3 112-M 255 57.3 3.9 2.4 7.8 1.2 13.7 13.7 113-M 271 43.2 4.1 4.4 8.1 1.1 14.0 25.1 114-M 219 47.0 1.8 0.9 11.4 — 12.3 26.5 115-F 238 44.5 4.6 7.1 11.8 0.4 14.3 17.2 116-F 208 35.1 9.1 6.3 9.6 1.4 21.6 16.8 117-M 269 48.0 5.2 3.3 11.9 1.5 12.6 17.5 118-F 324 50.6 5.6 2.5 8.6 — 13.3 19.4 201-M 230 34.8 5.7 3.0 9.6 0.4 15.7 30.9 TOTAL 11368 42.6 - 7.4 9.8 13.1 2.5 11.2 13.3 165 DISTRIBUTION (%) OF CONTEXTS BY AGE AND SEX CONTEXT: N S S M S OP S V S AV S TV S ATV AGE ( W K S ) 0 - 10 1518 45.1 37.3 3.2 5.9 — 1.6 6.8 11 - 15 2046 36.3 30.9 3.4 11.6 0.7 8.0 9.0 16 - 20 2498 49.8 26.3 6.7 2.9 0.4 7.6 6.2 21 - 25 2047 48.9 27.3 6.4 0.7 0.3 10.1 6.4 26 - 30 815 43.9 22.7 12.4 2.2 — 14.5 4.3 31 - 35 584 58.9 20.0 , 8.9 4.5 — 5.5 2.2 36 - 40 554 67.3 21.1 4.7 2.0 — 4.9 — 41-45 531 52.9 20.0 10.5 8.9 6.6 1.1 46 - 50 450 50.9 27.8 5.3 4.9 — 6.2 4.9 51 - 60 325 48.3 23.1 3.1 3.1 — 17.8 4.6 SEX FEMALE 4540 48.3 22.8 6.9 4.6 0.3 11.0 6.1 MALE 6828 47.2 30.9 5.4 5.0 0.3 5.6 5.7 TOTAL 11368 47.6 27.6 6.0 4.8 0.3 7.8 5.8 I 166 DISTRIBUTION (%) OF CONTEXTS BY SUBJECT CONTEXT: N S S M S OP S V S AV S TV S ATV SUBJECT 101-F 744 66.9 16.5 9.4 2.0 — 4.6 0.5 102-F 920 53.0 22.2 5.3 12.5 — 5.4 1.5 '103-M 1249 49.2 26.1 5.8 17.0 — 0.4 1.6 104-F 1298 44.5 12.4 5.2 5.1 — 17.1 15.6 105-M 684 64.2 18.3 8.9 3.2 — 5.4 — 106-F 808 48.8 35.8 1.0 — 1.7 6.3 6.4 107-M 792 33.8 49.2 9.5 — — 3.4 4.0 108-M 1053 62.6 10.3 0.7 — — — 26.4 109-M 661 38.3 37.5 8.9 4.7 7.1 3.5 110-M 415 61.7 23.4 — 10.1 — 4.8 — 111-M 730 32.6 27.9 6.0 4.4 1.0 25.8 2.3 112-M 255 35.7 54.9 — — — 9.4 — 113-M 271 49.4 32.5 4.8 — — 7.0 6.3 114-M 219 35.2 52.5 12.3 — — — — 115-F 238 24.4 43.7 18.5 2.5 — 10.9 — 116-F 208 35.1 24.0 17.3 3.4 — 20.2 — 117-M 269 35.7 49.1 4.8 — 4.1 6.3 — 118-F 324 31.8 31.5 12.0 — 23.1 1.5 201-M 230 42.2 57.8 — — — — . — TOTAL 11368 47.6 27.6 6.0 4.8 0.3 7.8 5.8 167 DISTRIBUTION (%) OF CONTOURS BY AGE (3 CLASSES) CONTOUR: N R - F F - R RISE FALL LEVEL R-F-R F-R-F AGE (WKS) 0 - 21 6489 39.5 7.8 11.2 14.9 3.1 10.5 13.1 22 - 38 3375 46.5 6.7 7.1 11.0 1.6 12.7 14.5 39 - 60 1504 47.2 7.7 10.2 10.3 1.4 11.4 11.8 DISTRIBUTION (%) OF CONTEXTS BY AGE (3 CLASSES) CONTEXT: N S S M S OP S V S AV S TV S ATV AGE (WKS) 0 - 21 6489 45.0 29.6 4.8 6.2 0.4 6.1 8.0 22 - 38 3375 50.5 25.7 7.9 2.0 0.2 10.6 3.1 39 - 60 1504 52.5 23.4 7.1 5.3 0.0 8.8 2.9 APPENDIX D MISCELLANEOUS DATA Page D i s t r i b u t i o n of vocalizations by subject •••• 169 Di s t r i b u t i o n of vocalizations for each subject by context 170 Di s t r i b u t i o n of vocalizations by contour 171 Di s t r i b u t i o n of vocal i z a t i o n s by context 172 168 169 DISTRIBUTION OF VOCALIZATIONS BY SUBJECT DATA EPOCH NO. OF OBSERVATIONS SUBJECT (IN WEEKS) SESSIONS NUMBER PERCENTAGE 101-F 5 -51 22 744 6.5 102-F 5 -54 22 920 8.1 103-M 7 -55 20 1249 10.9 104-F 5 -52 20 1298 11.4 105-M 5 -53 20 684 6.0 106-F 5 -54 19 808 7.1 107-M 5 -53 23 804 7.0 108-M 5 -21 8 1053 9.2 109-M 6 -55 18 661 5.8 110-M 5 -55 18 415 3.6 111-M 7 -55 19 730 6.4 112-M 5 -24 10 281 2.5 113-M 7 -26 11 271 2.4 114-M 6 -25 9 219 1.9 115-F 5 -24 9 238 2.1 116-F 8 -26 7 208 1.8 117-M 5 -24 9 269 2.4 118-F 4 -26 10 324' 2.8 201-M 5 -24 9 237 2.1 TOTAL: 283 11,413 100.0 N.B.— THE UTTERANCES OF THE 10 SUBJECTS (FEMALE: N = 4; MALE I N = 6) FOLLOWED OVER THE COURSE OF ONE YEAR CONSTITUTE 68% (N =7761) OF THE TOTAL SAMPLE/OBSERVATIONS. D I S T R I B U T I O N O F V O C A L I Z A T I O N S B Y S U B J E C T AND C O N T E X T S U B J E C T S S F S M S A N S A M S A F S V S A V S T V S A T V S O P S O T O T A L 1 0 1 - F 4 9 8 1 0 4 1 2 3 — 2 2 3 3 8 9 1 5 — 3 4 4 7 0 5 3 7 4 4 1 0 2 - F 4 8 8 2 1 2 2 0 4 — r IT 1 1 5 — 5 0 1 4 4 9 1 7 9 9 2 0 1 0 3 - M 6 1 4 1 6 2 3 2 6 — — 5 6 8 2 1 2 — 5 2 0 7 2 2 3 7 1 2 4 9 1 0 4 - F 5 7 8 1 8 2 1 6 1 — 1 9 1 3 1 6 6 6 — 2 2 2 2 0 3 6 8 4 9 1 1 2 9 8 1 0 5 - M 4 3 9 3 2 6 1 2 5 — 1 3 2 1 6 4 2 2 — 3 7 — 6 1 5 9 6 8 4 1 0 6 - F 3 9 4 — 2 8 9 — r 7 2 — 1 4 5 1 5 2 8 1 1 7 8 0 8 1 0 7 - M 2 6 8 7 3 " 3 9 0 1 2 1 — 2 1 — — 2 7 3 2 7 5 5 9 8 0 4 1 0 8 - M , ' 6 5 9 — 1 0 9 — — 7 1 2 7 8 7 2 7 8 1 0 5 3 1 0 9 - M 2 5 3 — 2 4 8 — — 5 9 5 3 1 — 4 7 2 3 5 9 1 0 1 6 6 1 1 1 0 - M 2 5 6 — 9 7 4 2 — 2 0 — — 6 2 4 1 5 1 1 1 - M 2 3 8 — 2 0 4 — — 4 4 U 3 2 7 1 8 8 1 7 4 4 2 4 4 7 3 0 1 1 2 - M 9 1 — 1 4 0 2 6 2 2 4 — — 2 4 2 8 1 1 1 3 - M 1 3 4 — 8 8 — — 1 3 1 — — 1 9 1 7 1 3 3 6 2 7 1 1 1 4 - M 7 7 1 5 1 1 1 5 — — 1 2 1 2 7 — 2 1 9 1 1 5 - F 5 8 1 4 1 1 0 4 — — 3 0 2 6 — 2 6 — 4 4 3 2 2 3 8 1 1 6 - F 7 3 1 3 1 5 0 -- — 2 3 2 7 — 4 2 — 3 6 4 9 2 0 8 1 1 7 - M 9 6 — 1 3 2 — — 1 3 2 — 1 1 1 7 — 1 3 2 8 2 6 9 1 1 8 - F 1 0 3 2 9 2 1 0 2 — • — 1 0 1 — — 7 5 5 3 9 8 0 3 2 4 2 0 1 - M 9 7 — 1 3 3 7 1 2 3 7 T O T A L : 5 4 1 4 2 4 1 3 1 4 0 4 5 5 6 3 8 8 5 4 8 3 2 8 8 4 6 6 5 6 8 5 2 1 2 9 1 1 4 1 3 N O T E : ( 1 ) C O N T E X T S 0 P _ = _S_F + S A M + S A F , G I V E N T H E S M A L L NUMBER O F O B S E R V A T I O N S I N T H E S E C A T E G O R I E S . C O N T E X T S AN HAS B E E N E X C L U D E D FOR T H E S A M E R E A S O N . C O N T E X T S 0 I S T H E A G G R E G A T E O F A L L FOUR O B J E C T C A T E G O R I E S . ( 2 ) S U P E R C R I P T S C 2 3 ' ~ ) I N D I C A T E T H E T O T A L NUMBER O F S E S S I O N S C O M P R I S E D I N T H E NUMBER O F O B S E R V A T I O N S C I T E D . D I S T R I B U T I O N O F O B S E R V A T I O N S B Y C O N T O U R 171 F E M A L E M A L E C O M B I N E D C O N T O U R (N=7- i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i + y) 

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