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Durations of acoustic segments under synchronous and delayed feedback conditions Jeffrey, Ingrid 1974

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DURATIONS OF ACOUSTIC SEGMENTS UNDER SYNCHRONOUS AND DELAYED FEEDBACK CONDITIONS  by  I n g r i d Jeffrey B . A . , Simon Fraser U n i v e r s i t y , 1972 .  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of Paediatrics D i v i s i o n of Audiology and Speech Sciences  We accept t h i s thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA July,1974  In p r e s e n t i n g t h i s t h e s i s  in p a r t i a l  f u l f i l m e n t o f the requirements  an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree the L i b r a r y I further  s h a l l make i t f r e e l y  available for  r e f e r e n c e and  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 copying o f t h i s  It  i s understood that copying or  thesis  permission.  Department of  PCLICLL  CLI^LCS  The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8. Canada  Date  Qdoltr  9*  /?7</  or  publication  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 not be a l l o w e d without my written  that  study.  f o r s c h o l a r l y purposes may be granted by the Head of my Department by h i s r e p r e s e n t a t i v e s .  for  ABSTRACT The  present  study  investigates durations  segments u n d e r s y n c h r o n o u s a n d d e l a y e d Three subjects their  normal r a t e  tory  a t a maximally feedback.  subject  a p a s s a g e and f o u r  (NORMAL), a t a s l o w r a t e  synchronous feedback, and  read  feedback  rate  The d e l a y  s t u d y were:  sentences a t  (SLOW DAF)  (FAST DAF) u n d e r d e l a y e d  u s e d was d e t e r m i n e d  s o i t w o u l d p r o d u c e maximum s p e e c h The  conditions.  (SLOW SAF) u n d e r  and t h e n a t a s l o w r a t e  fast  of acoustic  hypotheses under t e s t ,  f o r each  disturbance.  on t h e b a s i s  (a) t h a t u n d e r SLOW SAF a n d u n d e r  of a pilot delayed  f e e d b a c k , v o w e l s w o u l d be p r o l o n g e d p r o p o r t i o n a t e l y t h a n c o n s o n a n t s , and t h a t proportionately  continuants  more t h a n o b s t r u e n t s ;  audi-  more  w o u l d be p r o l o n g e d and (b) t h a t  close  v o w e l s w o u l d be p r o l o n g e d more u n d e r SLOW SAF and open v o w e l s more u n d e r DAF c o n d i t i o n s .  P o s i t i o n i n the s y l l a b l e  was e x p e c t e d  increases  to affect  selectively  i n duration  u n d e r DAF. The  results,  b a s e d on n o r m a l i z e d d a t a ,  t h a t v o w e l s were p r o p o r t i o n a t e l y  more p r o l o n g e d  s o n a n t s u n d e r SLOW SAF a n d DAF c o n d i t i o n s . c o n s o n a n t s were p r o p o r t i o n a t e l y e n t s u n d e r DAF c o n d i t i o n s SAF.  For the obstruents  confirmed than  con-  Continuant  more p r o l o n g e d  than  obstru-  b u t n o t c o n s i s t e n t l y u n d e r SLOW prevocalic  closure  was c o n s i s t e n t l y  more p r o l o n g e d u n d e r DAF t h a n u n d e r SLOW SAF. The  hypothesis  that  c l o s e v o w e l s w o u l d be p r o l o n g e d  more u n d e r SLOW SAF and open v o w e l s more u n d e r DAF was n o t in general  confirmed.  The s t u d y  position  i n the s y l l a b l e  segments  u n d e r DAF b u t a l s o u n d e r  further  not only  tion  SLOW SAF:  I t was a l s o  more  than the d u r a t i o n  found t h a t  o f vowels  o f open v o w e l s .  frequently  proportionately  the durations  i n other  o f t h e vowel / u / i n c r e a s e d  that  SLOW SAF  than other  Moreover,  vowels  i t i s hypothesized  o f vowels i n  proportionately  proportionately /u/ occurred  more  duration. that  the s y l l a b l e i s  the reflex  involved  disturbances.  speech  more  environments i n  a m o n i t o r e d u n i t u n d e r DAF and t h a t i n t h e DAF-induced  more  words and t h a t t h e  i n phonetic  which vowels a r e n o r m a l l y o f l o n g e r Finally,  posi-  prolonged.  words s u c h a s f u n c t i o n words i n c r e a s e d  than  Under  and u n d e r DAF c o n s o n a n t s i n p r e v o c a l i c  were p r o p o r t i o n a t e l y  duration  that  affected durations of  c o n s o n a n t s i n p o s t v o c a l i c p o s i t i o n were more p r o l o n g e d  indicated  level i s  TABLE OF CONTENTS Page ABSTRACT  i i  TABLE OF CONTENTS  iv  L I S T OF TABLES  vi  L I S T OF FIGURES  vii  ACKNOWLEDGEMENT  viii  Chapter 1  INTRODUCTION  1  Chapter 2  LITERATURE REVIEW  5  2.1  Introduction  5  2.2  Experiments  5  2.3  Discussion.  18  Chapter  3  AIMS OF THE INVESTIGATION  . 37  Chapter  4  EXPERIMENTAL APPARATUS AND PROCEDURES.  . 39  Chapter 5  Chapter  6  4.1  Subjects.  39  4.2  Experimental Design  39  4.3  Instrumentation  4.4  Calibration  44  ANALYSIS OF DATA  46  5.1  Instrumentation  46  5.2  Segmentation  47  5.3  Segment R e j e c t i o n C r i t e r i a  and Arrangement  Criteria  .  .  43  52  RESULTS AND DISCUSSION  55  6.1  Pilot  55  6.2  S c r e e n i n g Study  Study  iv  .  58  Page 6.3  R e s u l t s of the 6 . 3"*"  Main Experiment.  .  .62  Relative Durations  65  2 6.3  R e l a t i v e Change M e a s u r e  . . .  65  3  6.3  R e l a t i v e Change o f V o w e l s  .  .  68  6.3  R e l a t i v e Change o f C o n s o n a n t s  79  6.3^  Repetitions  87  4  6.4  Summary a n d C o n c l u s i o n s .  .  .  .  .  .91  BIBLIOGRAPHY  95  APPENDIX  98  v  L I S T OF  TABLES  Table  Page  I.  Normal r e a d i n g t i m e u n d e r SAF and d e l a y s p r o d u c i n g p e a k s o f d i s t u r b a n c e as d e f i n e d by t h e d u r a t i o n - e r r o r r a t i o d e s c r i b e d i n c h a p t e r 4 . . 59  II.  Between-condition differences i n r e l a t i v e change o f v o w e l s i n o n e - s y l l a b l e f u n c t i o n words  70  Within-condition differences i n relative change o f ' s t r e s s e d ' l o n g v o w e l s and v o w e l s i n f u n c t i o n words  71  III.  IV.  W i t h i n - c o n d i t i o n d i f f e r e n c e s i n r e l a t i v e change o f ' s t r e s s e d ' v o w e l s and / a / n o t i n f u n c t i o n words 73  V.  Within-condition differences of ' s t r e s s e d ' vowels  VI.  Between-condition differences of a s p i r a t i o n a f t e r ' i n i t i a l '  vi  in relative  change 76  i n r e l a t i v e change v o i c e l e s s c l o s u r e 84  L I S T OF FIGURES  Figure  4.1  5.1 5.2  Page  Block diagram o f i n s t r u m e n t a t i o n f o r prod u c i n g t h e d e l a y e d f e e d b a c k and f o r r e c o r d ing  43  Block diagram o f i n s t r u m e n t a t i o n p r o d u c e mingograms  46  Mingogram o f p a r t timz/  o f the phrase  used t o /gridi 48  5.3  Mingogram o f t h e p h r a s e / f u l s /  49  5.4  Mingograms o f t h e p h r a s e s /wAn/, / r A f t / , and /juz/ . .  50  5.5  Mingogram o f t h e p h r a s e / 6 s J a f t /  51  5.6  Mingogram o f t h e s e q u e n c e  /rAIdAbAOAbAboa/. o  6.1  6.2  o  o  . .53  °  DAF-induced speech d i s t u r b a n c e (error-duration r a t i o ) f o r male s u b j e c t 1, and f e m a l e s u b j e c t s 2 and 3  61  A v e r a g e ' t o t a l d u r a t i o n s ' o f t h e main ment s e n t e n c e s i n t h e f o u r c o n d i t i o n s  63  experi-  6.3  R e l a t i o n s h i p o f ' s t r e s s e d ' long vowels, 'other' v o w e l s , and c o n s o n a n t s i n t h e m a i n e x p e r i m e n t sentences i n the four c o n d i t i o n s .66  6.4  R e l a t i v e change i n d u r a t i o n f o r v o w e l s i n t h e SLOW SAF ( I I ) , t h e SLOW DAF ( I I I ) , and t h e FAST DAF (IV) c o n d i t i o n s w i t h r e s p e c t t o t h e NORMAL c o n d i t i o n  69  6.5  R e l a t i v e change i n ' i n i t i a l ' v o i c e l e s s c l o s u r e , ' f i n a l ' v o i c e l e s s s t o p s , ' i n i t i a l ' /m/ and ' f i n a l ' nasals 81  6.6  R e l a t i v e change i n a s p i r a t i o n i n t h e SLOW SAF, SLOW DAF a n d FAST DAF c o n d i t i o n s w i t h r e s p e c t t o t h e NORMAL c o n d i t i o n  83  Number o f r e p e t i t i o n s and c u m u l a t i v e t i t i o n s i n t h e FAST DAF c o n d i t i o n  88  6.7  vii  % repe-  ACKNOWLEDGMENT  I would l i k e for  the help  t o e x p r e s s ray s i n c e r e  I have r e c e i v e d i n c o m p l e t i n g  appreciation this  thesis.  My t h a n k s go e s p e c i a l l y - To D r . A-P. B e n g u e r e l w i t h o u t whose t i m e a n d a d v i c e t h e s i s w o u l d n o t have b e e n p o s s i b l e ;  this  - To D r . J . B . D e l a c k , n o t o n l y f o r b e i n g on my t h e s i s committee, b u t p a r t i c u l a r l y f o r h i s c o n c e r n and i n t e r e s t always; - To D r . R. G r e g g committee;  f o r h i s time spent  - To D r . J.H. G i l b e r t ment ;  and C a r o l y n  s e r v i n g on my  for their  kind  encourage-  - To D r . R.P. Gannon f o r p e r m i s s i o n t o u s e t h e f a c i l i t i e s of t h e A u d i o - V e s t i b u l a r U n i t a t Vancouver General Hospital; - To The P s y c h o l o g y for  Department  a t Simon F r a s e r U n i v e r s i t y  the loan o f the K o r t i n g tape  - To J i m a n d K a t h y  for their  love  recorder;  and  understanding;  - To S h a r o n , P a t , L y n n e , B e t t y a n d M e r a l i n we s h a r e d ; - To R o b i n f o r h e r work on t h e d r a w i n g s ; - To Rose a n d M a r g a r e t - And t o my s u b j e c t s  for  f o r the closeness  typing;  for their patience  and c o o p e r a t i o n .  Chapter  1  INTRODUCTION  The execution In  of voluntary  the production  involving anism, in  importance  and t h e v o c a l  movements,  movements  required  always  initiated  be  at  which  of  factors  to  impulses such  a number  articulators, f o l d s have  of such  commands  a t t h e same  point  fired  100).  duction  of a particular  already  be p r e s e n t .  Speech,  of a  "mass that  features  i n other  followed  by a n o t h e r ,  neural  commands w i t h  time.  The  movements subject  length  o f a sound  cannot The  by  required  a  sequence number  by t h e  of tissue that must  be  during  the  pro-  sounds  does  movements  the length  has  performed"  of later  words,  o f one d i s c r e t e s e t o f c o o r d i n a t e d i n the production  sound  i n time.  time  coordinated  f o r the various  Furthermore,  sound,  movements  a set of co-  i s determined  i t sd e s t i n a t i o n ,  1967, p.  recognized.  of voluntary  f o r the production  be  been  t o be p r e c i s e l y  the neural  will  f o r t h e smooth  t h e r e s p i r a t o r y mech-  and t h e amount o f work  (Lenneberg,  ing  has long  as t h e t r a v e l l i n g  to reach  be moved  sist  feedback  To add t o t h e c o m p l e x i t y  ordinated  impulse  movements  of speech  the various  time.  of sensory  of a  not conresultphoneme  but consists of a set of discrete associated  movements  of the production  are integrated  has been  unit  coordinated or units  and continues  i n  i n which  t o be  of investigation. It  has been  may  suggested  (Smith,  1962)  that the  a  -  motion a  system  bonea  patterns  nels,  what  their  A  and t h e i r means  auditory found  that  back  a r e masked  erably the  when  both  palate  bone-  pitch  patterns  and v o i c e  1967,pp.  163-164). Introducing  delayed  auditory  side-tone,  ference,  delaying  feedback  during  ing  properties  properties the  extent.  this  (DAF),  time  of the environment,  auditory  feedback  will  been feed-  are consid-  I t has a l s o changes  input,  also  (Ladefoged,  vocal  a method  known  r e f e r r e d t o as  employed  method  inter-  on t h e o c c l u d -  t h e sound  the length  of  of the auditory  Depending  signal,  been  of intonation  the speaker's  earmuffs,  a m p l i f i c a t i o n of the delayed  delayed  about the  auditory  vowels  of arrival  production.  of the headset  chan-  questions.  i t has  condition  between  i s a frequently the usual  noise,  auditory  feedback  speech  collected  and t h a t  a delay  chan-  and q u a l i t y , and c o n t r o l o f  t o some  and h i s a i r - c o n d u c t e d  delayed  t o these  and a i r - c o n d u c t e d  under  such  and  the feedback  answers  intensity  occur  feedback  of monitoring  F o r example,  increases  kinesthetic,  available to  of these  has been  i n length  by  importance?  sought  of data  i s lost  that  as  relative  by h i g h  observed  output  nature  mechanism.  a f f e c t e d both  soft  channels  of interference with  amount  feedback  tactile,  i n the process  i n v e s t i g a t o r s have  considerable  With  feedback  i s the precise  utilization  By  a r e c o n t r o l l e d and m o n i t o r e d  mechanisms.  and a i r - c o n d u c t i o n  controlling,  nels,  of speech  of feedback  system,  2 -  absorbing  of the delay, fragments  and  o f un-  be a v a i l a b l e t o t h e s p e a k e r .  -  Early Black, of  1951;  3 -  investigators  (Lee, 1950a, 1950b,  F a i r b a n k s , 1955)  found t h a t  speech p r o d u c t i o n , i n c r e a s e s v o c a l  mental  f r e q u e n c y , and  stitutions, primarily  results  o m i s s i o n s and  of r e p e t i t i o n s  Such  DAF-induced  cial  stutter" The  (Lee,  slows  intensity  i n speech e r r o r s  additions;  1951),  another  study reports  a t 200 msec 180  d e l a y f o r m a l e s and 1965).  under to  feedback  sures of t o t a l  since  studies  implicitly  ments i n t h e t e s t  termed  global  considerable t o cope  b e h a v i o u r c a n be must t h e r e f o r e  with  employed from  subject  expected.  be v i e w e d  t h e measures employed  in relation  and  with  i n most Mea-  to speech u n i t s  such  o r words c o n t a i n e d i n t h e r e a d p a s s -  assume a u n i f o r m s l o w i n g o f a l l e l e -  passage  increase of a r t i c u l a t o r y has  that  i n the a b i l i t y  disturb-  are of a very g l o b a l nature.  r e a d i n g time  either  Still  (Mahaffey  as i n t h e s t r a t e g i e s  comparisons  msec  1955).  Considerable variation  as phonemes, s y l l a b l e s , age  "artifi-  the maximally  be m e n t i o n e d  exist  as w e l l  caution, p a r t i c u l a r l y t h e p a s t DAF  1958).  a t 180  msec f o r f e m a l e s  i n the r e s u l t i n g  Between-subject  of  270  such c o n d i t i o n s .  subject  consist  e x p e r i m e n t a l l y , and  (Fairbanks,  msec t o be  I t might  individual differences delayed  sub-  1951).  (Black,  Stromsta,  s u c h as  Guttman,  m a x i m a l s p e e c h d i s t u r b a n c e has b e e n r e p o r t e d  ing  rate  funda-  have a l s o been t e r m e d  d e l a y has b e e n v a r i e d  and  the  and  the l a t t e r  ( F a i r b a n k s and  repetitions  DAF  1951;  rate,  o r a s l o w i n g m a i n l y due errors.  that  O n l y what A l l e n  i s , the average  rate  to (1973) at  which  -  phonemes,  syllables,  4 -  and w o r d s a r e p r o d u c e d , c a n be  ed f o r b y s u c h m e a s u r e s .  A more d e t a i l e d a n a l y s i s i s  t o l e a r n a n y t h i n g about what A l l e n rate, within  that i s ,  "the  syllables"  specification  (ibid.,  p.  referred  of global rate.  as a f u n c t i o n  local  local  durations  rate is partly a  local  rate  change  L i n e a r r e l a t i o n s h i p s c a n be  e x p e c t e d o n l y f o r a n a r r o w r a n g e o f tempos  (ibid.,  p.  T h i s study proposes t o i n v e s t i g a t e changes local  r a t e as a f u n c t i o n  feedback  (SAF) as w e l l  of global rate,  as u n d e r D A F .  u n d e r SAF i s a l t e r e d and t h e e f f e c t s termined, local  can the e f f e c t s  r a t e be  assessed.  needed  222).  How t h e n d o e s  of global rate?  t o as  o f segment  As A l l e n h a s p o i n t e d o u t , function  account-  under  in  synchronous  Only i f g l o b a l on l o c a l  222).  rate  r a t e are  o f D A F - a l t e r e d g l o b a l r a t e on  de-  Chapter 2 LITERATURE  2.1  Introduction In t h i s  be b r i e f l y  discussed ation  section  described  and u n d e r l y i n g  of  REVIEW  the pertinent  i n chronological  assumptions  i n an a t t e m p t  as i t r e l a t e s  DAF e x p e r i m e n t s  order.  will  The r e s u l t s  of the experimenters w i l l  at a synthesis of available  be inform-  t o t h e DAF mechanism and p o s s i b l e  units  speech p r o d u c t i o n .  2.2  Experiments A summary i n t a b l e  described dix  form o f t h e experiments  t o be  i n t h e f o l l o w i n g p a g e s c a n be f o u n d i n t h e a p p e n -  (Appendix A ) . Lee  first  called  ( 1 9 5 0 a ) , one o f t h e e a r l i e s t  DAF e x p e r i m e n t e r s ,  t h e method o f DAF t o t h e a t t e n t i o n  of i n v e s t i -  g a t o r s a s a means o f s t u d y i n g  feedback p r o c e s s e s .  own e x p e r i m e n t s  some s u b j e c t s were a b l e t o  avoid  he f o u n d t h a t  t o some e x t e n t t h e e f f e c t s  result  of being able  sources  DAF,  o f DAF, p r e s u m a b l y  t o c o n c e n t r a t e on o t h e r  as a  feedback  f o r monitoring purposes. I n one e x p e r i m e n t  jects  Inh i s  t o read a passage  L e e (1950b) r e q u i r e d  first  h i s sub-  w i t h o u t d e l a y and t h e n  under  w h i l e m a i n t a i n i n g a c c u r a t e s p e e c h , w h i c h he d e f i n e d  as s p e e c h w i t h o u t r e p e t i t i o n s He s u g g e s t e d  that  this  and s p e e c h a t an e v e n  rate.  c o u l d be a c c o m p l i s h e d by c o o p e r a t i n g  -  5 -  -  with  the slowing  6 -  down e f f e c t ,  i n order  c a d e n c e demanded by t h e d e l a y e d  to "achieve the  feedback"  (ibid.,  p. 824).  Under t h e DAF c o n d i t i o n s , a l l b u t one o f h i s s u b j e c t s were found  t o have c o n s i d e r a b l y i n c r e a s e d t o t a l  from t h e no-delay delay  the longer  condition. the t o t a l  to repeat  time  as r a p i d l y  taken.  for  Again,  the t o t a l  syllable  time  required  t h e r e p e t i t i o n s was l o n g e r u n d e r DAF. Lee  (1951) r e m a r k s t h a t h i s s u b j e c t s e i t h e r  ed down and spoke w i t h attempted ed  ( L e e , 1950b) s u b j e c t s were  as p o s s i b l e a s i n g l e  ( t h r e e phonemes) 40 t i m e s .  times  Furthermore, the longer the  In a second experiment asked  reading  to maintain  syllables  normal speed, they  and c o n t i n u a n t  Black effects  increased intensity,  (1951),  independently  a series  of f i v e  delays.  The o r d e r  o r when  sounds.  who had been i n v e s t i g a t i n g  five-syllable  phrases  under  11 d i f f e r e n t  of p r e s e n t a t i o n of the delay c o n d i t i o n s  t o "speak n a t u r a l l y "  (ibid.,  increased  p r o g r e s s i v e l y with  d e l a y o f 180 msec.  With  again, without, duration.  Subjects  p. 57). I t  t h a t t h e mean d u r a t i o n o f e a c h s e r i e s  zero-delay  DAF  o f Lee, r e q u i r e d h i s subjects t o read  was f o u n d  decreased  they  h a l t e d and r e p e a t -  was r o t a t e d s y s t e m a t i c a l l y among t h e s u b j e c t s . were i n s t r u c t e d  slow-  of  an i n c r e a s e i n d e l a y  up t o a  l o n g e r d e l a y s mean r e a d i n g however, a p p r o a c h i n g  phrases  times  the shorter  -  7 -  "The e f f e c t o f i n c r e a s i n g t h e d e l a y f r o m 30 t o 60 msec i s p r o p o r t i o n a t e l y g r e a t e r t h a n t h e e f f e c t o f any o t h e r c o m p a r a b l e 30 msec i n c r e m e n t w i t h i n t h e r a n g e o f t h e s t u d y " ( i b i d . , p. 6 0 ) . Intensity, t i e s per  the  as  the d e l a y  the nature  of the  spectrographic repeated  final  to  Harris  90  How-  msec.  (1954) o f  r e v e a l e d , based  first  expected  msec.  syllable  transition  repeated  to  on be  to the  syllable  next  showed a l l  p r o p e r t i e s of the corresponding  segment  SAF.  a passage f i r s t sented  (1955) r e q u i r e d h i s s u b j e c t s t o  without  delay  i n random o r d e r . as you  ized with  increased average  .  with  p.  DAF  longer  i n the  conditions.  prior  T h e r e was  and  was  to  familiar-  to the  experiment.  (each  i n s t a n c e of  tallied  durations with  as  one  and  without in  Vocal  graphic  sound p r e s s u r e  (mean o f  r e f e r e n c e f o r a l l samples)  c o n d i t i o n s by no  was  instructed  pre-  200-msec d e l a y c o n d i t i o n t h a n  same a r b i t r a r y  i n t h e DAF  total  read  at four delays  335)  length or nature  e r r o r ) were made and  peaks, r e the  then  showed t h a t more e r r o r s  regardless of  other  (ibid.,  t h e p a s s a g e and  pauses o b t a i n e d  and  E a c h s u b j e c t was  u s u a l l y do"  Results  any  o n l y up  stutter  intensi-  increased  t o 270  R a w n s l e y and  t h a t the  the  whereas the  Fairbanks  error  by  analysis,  transitional  "read  i n c r e a s e d up  artificial  later,lacked  syllable,  under  study  peak  phrase),  i n c r e a s e s were s i g n i f i c a n t A brief  the  t h e mean o f 15  c o n d i t i o n (three peaks per  progressively ever,  b a s e d on  substantial  10  to  12  dB  on  was  the  change i n s o u n d  pressure  -  increases  over  fundamental changed crease  the range o f time d e l a y s  frequency  little  increased  as a f u n c t i o n  ammounted  (ibid.,  8 -  studied.  as a f u n c t i o n  of delay  t o "about t h r e e  Similarly,  o f DAF, b u t  interval.  and o n e - h a l f  The i n -  semitones"  p. 341). F a i r b a n k s t e r m e d a r t i c u l a t o r y e r r o r s , and  duration  " d i r e c t e f f e c t s " and mean sound p r e s s u r e  fundamental p.  frequency  3 4 1 ) , on t h e b a s i s In  addition,  increases of t h e i r  "indirect  delayed  "using  different functions.  the subject  increased  of  e r r o r s under t h e v a r i o u s  delay the  the  and d u r a t i o n  error  rate  interaction  duration  increased  while durational  rate of error  error  constants"  delay  increased  (ibid.,  remained  constant,  then  as a f u n c t i o n  of delay.  If  f u n c t i o n w o u l d be a f l a t  o f e r r o r and d u r a t i o n  proportionately, one.  Thus, the  i s r e f l e c t e d i n such a  The a c t u a l p l o t t e d  increased  more a t 200 msec t h a n a t any o t h e r  that  the rate of  as a f u n c t i o n o f  measure.  revealed  p. 342).  I f , on t h e o t h e r  b o t h were t o i n c r e a s e  p l o t was b a s e d on means.  f o r the un-  conditions,  his errors  increases  to a  y e t made t h e same amount  as a f u n c t i o n o f d e l a y .  hand, t h e s u b j e c t  of delay  t h e mean r a t e s  as r e s p e c t i v e  If  error decreased  (ibid.,  t h e r a t e o f a r t i c u l a t o r y e r r o r and  rate ordinate, condition  and  effects"  c o r r e c t word r a t e was p l o t t e d a s a f u n c t i o n relative  increased  function  revealed  that  delay.  Study o f i n d i v i d u a l  errors The  recordings  -  9 -  " t o t a l d i s t u r b a n c e i n a g i v e n sample i n v o l v e d i n many c a s e s a s e e m i n g compromise w i t h the i n t e r f e r e n c e , i n which d u r a t i o n was ' t r a d e d ' f o r a r t i c u l a t i o n , or v i c e v e r s a , but i n p r o p o r t i o n s t h a t v a r i e d f r o m c a s e t o c a s e " ( i b i d . , p. 3 4 3 ) . The  ratio  total  o f c o r r e c t words p e r  tend  gested with  decreases  d u r a t i o n i s i n c r e a s e d , o r number o f c o r r e c t  decreased. not  time u n i t  I n s u c h a m e a s u r e n u m e r a t o r and  to c a n c e l each o t h e r .  the  words  denominator  do  Fairbanks, therefore,sug-  f o l l o w i n g measure o f DAF  d i s t u r b a n c e , however,  the o b j e c t i v e t h a t i n t e r c o m p a r i s o n  c o u l d be made more  i f either  of d i f f e r e n t  texts  objectively:  II  W I = X  C  D n  WD t  '  o  where W i s o b t a i n e d number o f c o r r e c t w o r d s , D i s n o r m a l d u r a t i o n , W^. i s t o t a l number o f w o r d s , and D i s o b t a i n e d d u r a t i o n , D /W b e i n g a c o n s t a n t f o r t h e t e x t " ( i b i d . , p. 344). c  n  Q  The described  sentences  experimental  study  F a i r b a n k s and  Guttman  omission,  (1958) as  follows:  t o one  t r e a t e d by  three  as b e f o r e  i n agreement w i t h  t  i n the p r e v i o u s l y  were f u r t h e r  o f t h e p a s s a g e were a n a l y z e d  findings.  assigned  data obtained  ( F a i r b a n k s , 1955)  s u l t s d e s c r i b e d t o be ported  n  additional and  re-  the p r e v i o u s l y r e -  E r r o r s o f a r t i c u l a t i o n were l o c a t e d of the  addition,  following categories:  plus a miscellaneous  and  substitution,  category.  showed t h a t "number o f i n s t a n c e s o f e r r o r v a r i e d s u b s t a n t i a l l y with both delay i n t e r v a l and t y p e o f e r r o r " ( i b i d . , p. 2 1 ) .  Results  -  The  number o f d i s t u r b a n c e s o f c e r t a i n  specific present vals.  values  of delay,  in different  repetitions.  o f e r r o r s were  for different  that during  delay  inter-  t h e 200-msec d e l a y  The l e n g t h o f e r r o r  con-  classified  (number o f phonemes  s u b s t i t u t e d , e t c . , i n any one i n s t a n c e o f e r r o r )  was a l s o i n v e s t i g a t e d . repetitions  involving  T h e r e were more s u b s t i t u t i o n s and  two t o f o u r o r more phonemes and t h r e e  t e n phonemes r e s p e c t i v e l y  than  were r e l a t e d t o  a d d i t i o n s were most numerous, 70% b e i n g  omitted,  to  types  i . e . , the types  proportions  I t i s of interest  dition, as  10 -  i n any o t h e r  i n t h e 4 00 msec d e l a y c o n d i t i o n  condition.  However, e r r o r s  involving  f e w e r phonemes o c c u r r e d more f r e q u e n t l y and were f o u n d  to  be most numerous i n t h e 200-msec d e l a y c o n d i t i o n . A description complete without  mention o f the f o l l o w i n g study  (1958):  i n the f i r s t  subjects  to repeat  (ibid., and  o f t h e DAF l i t e r a t u r e w o u l d n o t be  o f two c o n d i t i o n s , Chase a s k e d h i s  t h e sound  [b] "as q u i c k l y as p o s s i b l e "  p . 585) a t z e r o d e l a y ,  stopping  at a signal  after  starting five  s e c o n d c o n d i t i o n a 216-msec d e l a y Results  seconds. was  signal  In the introduced.  showed t h a t 15 o f h i s 20 s u b j e c t s r e p e a t e d t h e under the d e l a y c o n d i t i o n  u n d e r t h e SAF c o n d i t i o n . A much more d e t a i l e d  been c a r r i e d and  at a given  interval  sound f r o m two t o s e v e n more t i m e s than  by C h a s e  o u t up t o t h i s  C h i s t o v i c h (1965).  recite  study  time  o f DAF e f f e c t s  was a t t e m p t e d  t h a n had  by K o z h e v n i k o v  F i v e s u b j e c t s were r e q u i r e d t o  t e n p r e v i o u s l y learned phrases  o f about  14-25  speech  -  sounds e a c h t w i c e  11  u n d e r SAF  -  conditions  and  at four  different  delays. The an the  f o l l o w i n g p a r a m e t e r s were r e c o r d e d  oscillograph: tongue w i t h  alveolar  and  an  between l i p s ,  artificial  palate  alveopalatal regions.  measure r e v e a l e d imum i n c r e a s e s greatly  contact  t h a t the  i n terms of and  the  subject  creases on  the  For  were f o u n d .  one  Further  f o u r s u b j e c t s who  ation of  the  in  the  phoneme-per-second  however, s u b j e c t s  d u c e d maximum d i s t u r b a n c e disturbance.  points  of  150-300 msec r a n g e p r o d u c e d max-  i n duration;  from each o t h e r  means o f  voice, contact  at three A  by  the  delay  which  pro-  i n terms of the magnitude a l m o s t no  a n a l y s i s was  were a f f e c t e d by  oscillograms  differed  of  durational i n -  therefore DAF.  An  based examin-  revealed  " m u l t i p l e c l o s i n g and o p e n i n g o f one and t h e same c o n t a c t s i n s t e a d o f t h e i r o n e - t i m e c l o s i n g and o p e n i n g as i n t h e n o r m a l s p e e c h " ( i b i d . , p. 145) for  a l l values  of delay.  P e r c e p t u a l l y , the  s e q u e n c e o f open s y l l a b l e s .  Repetitions of  u n i t s were a l s o o b s e r v e d , t h e m a j o r i t y of  470  msec.  Such a r e p e a t e d  have b e e n a c c o m p a n i e d shorter  speech  occurring at a  u n i t was  delay  reported  to  t h e m u l t i p l e c l o s i n g and  opening  above. Further  contact  longer  a  a t t i m e s by m u l t i p l e r e p e t i t i o n s o f  s e g m e n t s , i . e . , by  described  longer  r e s u l t was  analysis revealed  c l o s u r e and  f u n c t i o n of delay  contact  interval,  t h a t the  opening d i d not but  durations change as  were a p p r o x i m a t e l y  of a  constant  -  u n d e r DAF c o n d i t i o n s . were a p p r o x i m a t e l y opening  movements  The d u r a t i o n s o f c l o s u r e a n d  t h e same.  counted, crease  movements  i t was f o u n d  i n delay.  fact  lead  t o a decrease  two s u c h  i n one s u c h  t h a t t h e number  of closing-  clos-  incidence)  increased with  were an i n -  d u r a t i o n measures d i d n o t r e f l e c t  s i n c e p r o l o n g a t i o n o f a sound was a l s o f o u n d t o  from c l o s i n g  consonants  i n multiple repetitions.  t o opening  speech not delayed  found  occurred  opening  i n v o l v e d i n any one  (provided a t l e a s t  Total  this  When t h e number  o f t h e same c o n t a c t s  incidence of repetition ing-opening  12 -  was f o u n d  u n d e r DAF.  (C) and v o w e l s  The t r a n s i t i o n  t o be t h e o n l y a s p e c t o f  More complex  (V), i f a l t e r e d  sequences o f  by DAF, were  c h a n g e d as f o l l o w s : " CVC = CV + CX CCV = CX + CV CVCC = CV + CX + CX where X i s a r e d u c e d  vowel"  E v e n i f t h e c o n s o n a n t was v o i c e l e s s ,  (ibid.,  p. 156).  the opening  of the  c l o s u r e was a c c o m p a n i e d by v o i c i n g . Final to  vowels  i n a series  o f r e p e t i t i o n s were  be o f l o n g e r d u r a t i o n and t o c o i n c i d e w i t h  under normal feedback c o n d i t i o n s . final fairly  vowels i n a s e r i e s constant  found  durations  The d u r a t i o n s o f n o n -  o f r e p e t i t i o n s were f o u n d  t o be  and u n r e l a t e d t o d u r a t i o n s o f v o w e l s i n  normal feedback c o n d i t i o n s . In each study, place a value differences  i n w h i c h an a t t e m p t was made t o  on t h e m a x i m a l l y d i s t u r b i n g d e l a y ,  have been a c o n s i d e r a b l e s o u r c e  individual  of variance.  -  MacKay  (1968) h y p o t h e s i z e d  ated with  the delay  (peak s h i f t  13 -  t h a t s p e e c h r a t e m i g h t be  interval  hypothesis).  producing  I n one o f a s e r i e s  asked a d u l t s u b j e c t s t o repeat fast,  s l o w , and v e r y  conditions. the  Number o f e r r o r s  with  hypothesis:  sentences  imum r a t e o f s p e e c h w i t h  delay  the f a s t e s t  producing  series  a t a max-  delay  value,  i t was f o u n d  that  r a t e o f s p e e c h u n d e r t h e SAF repetitions  u n d e r DAF.  The  maximal d i s r u p t i o n , as c a l c u l a t e d  interval  was f o u n d  t o t h e maximum  the  sentences  and a t f i v e  from a c o r r e c t s y l l a b l e t o be r e l a t e d  i n t h e same  was c o n f i r m e d :  e x h i b i t e d the fewest  of delay  values.  experiment  no d e l a y  hypothesis  subjects with  length  t h e peak  t h e r e were p r o p o r t i o n a t e l y f e w e r e r r o r s  o f e x p e r i m e n t s when s u b j e c t s r e p e a t e d  condition  a t a maximally  His r e s u l t s d i d not confirm  However, i n a n o t h e r  the  o f s t u d i e s he  ( r e p e t i t i o n s ) was c h o s e n a s  d i m i n i s h i n g r a t e s f o r both  t h e peak s h i f t  disturbance  s l o w r a t e o f s p e e c h u n d e r two d e l a y  dependent v a r i a b l e .  shift  maximum  correl-  ( i n seconds per s y l l a b l e ) , r a t e o f speech i n  SAF c o n d i t i o n . "The s l o w e r a s u b j e c t ' s maximum r a t e of speech, the longer h i s c r i t i c a l DAF i n t e r v a l . " ( i b i d . , p. 819). What l i t t l e  to t h i s  date  Huggins  (1968).  of  The t e s t m a t e r i a l i n t h i s one c o n t a i n i n g o n l y  containing only  utterance  r a t e u n d e r DAF  i s due p r i m a r i l y t o t h e i n v e s t i g a t i o n s o f  two s e n t e n c e s ,  other  i s known a b o u t l o c a l  consisted  short vowels, the  long vowels, both  s e r v i n g as a frame.  study  p r e c e d e d by a s h o r t  The s u b j e c t was  familiarized  -  with  DAF  prior  to  "speak  in  the  fore  The  a  of  V.U.  each  at  a  as  she  were  and  was  i n both,  read  values  20 of  readings  could,  sentence."  level  33  -  experimental  meter  speaking  sentences  once  the  fluently  middle  her  stant  as  to  14  and  and  to  t r y not  (ibid.,  p.  told  maintain  to  normal  times delay  at  54).  and  delay,  zero  and  instructed pause  She  had  be-  the  same  con-  conditions.  delay  finally  to  and  again  then at  zero  delay. When tion  was  peaks  plotted  of  highest (mean at  a  the  syllable lower  value  at  delay). Fine  every at  of  of  f u n c t i o n of f o r both  310  delay  each  delay  sentences  sentence  sentence  with  msec  than  at  the  (mean  segment  values' of  delay  produc-  interval,  several  evident.  longer  zero  occurred  peak  for  duration  measuring  sentence  at  spectrograms.  The  syllables  delay)  highest  syllable  i n each from  sentence  were  the  a n a l y s i s consisted of  acoustic  12  duration  duration  syllable  and  a  f o r the  shorter  of  as  disturbance peaks  zero  total  the  the  160  msec  duration  zero  delay  I t was  found  that " t h e d u r a t i o n o f some s e g m e n t s was equal t o , or even s h o r t e r than, the duration with zero delay" (ibid., p. 56); (/t/  in / s i l i / ) .  segments while the  tended  the  delay  initial  The to  durations (initial  durations  remain  of  constant  unstressed as  of  other  segments  and  final  / s / and  voiceless stops,  /!/  and  the  delay  grew ///,  / r / in  syllable changed,  linearly closure  of  intervocalic  with  -  position  i n a stressed syllable,  syllables, inal  15 -  long vowels i n s t r e s s e d  s h o r t vowels, i n t h e l a s t  syllable  before  a term-  juncture). " S t i l l o t h e r segments h a d a d u r a t i o n t h a t d i d n o t change as t h e d e l a y was c h a n g e d , b u t was a b o u t 6 0 msecs l o n g e r t h a n t h e d u r a t i o n w i t h zero d e l a y " ( i b i d . , p. 56);  (occurred with  a l l p h o n e s , sometimes i n a d d i t i o n t o t h e  linear increase). A total and  o f 48 r e p e t i t i o n s  19 r e p e t i t i o n s  of which occurred the  repeated  separately, An  i n a l l long sentences  correlated  ly  highly with  length of delay.  the e a r l i e r  d e s c r i b e d e x p e r i m e n t by  However, F l e t c h e r and Y a t e s and o n l y a p p r o x i m a t e l y  had no  the subjects  DAF).  prior  experience  i n Chase's study  the experimenter  used a h i g h e r  t h e same d e l a y  with  DAF;  values.  ( i t i s n o t known  were n a i v e w i t h  S u b j e c t s were r e q u i r e d t o r e p e a t  after  Duration of  a t t e m p t was made r e c e n t l y by F l e t c h e r and Y a t e s  feedback l e v e l  if  most  segments, w h i c h were m e a s u r e d and a n a l y z e d  (1958).  Subjects  sentences  were c o u n t e d ,  a t 180, 240, and 360 msec.  (1971) t o r e p l i c a t e Chase  i n a l l short  respect to  each sound  and were i n s t r u c t e d  correct-  to repeat the  sounds as q u i c k l y as p o s s i b l e b u t e x a c t l y as p r a c t i c e d . Speed was t e r m e d acy  "vital"  "important"  ( F l e t c h e r and Y a t e s ,  ment was a l s o e x t e n d e d consonants besides repeated the  1971, p . 7 5 ) .  to include repetitions  [b]. Results  sounds fewer times  results  i n the i n s t r u c t i o n s  showed t h a t  and a c c u r The e x p e r i -  o f 19 o t h e r subjects  u n d e r DAF, a c o n t r a d i c t i o n o f  r e p o r t e d by C h a s e .  -  16 -  In o r d e r t o reduce f a t i g u e similar  results  could  t h e sounds under  Only  prior  two  further  12 c o n s o n a n t s were r e p e a t -  one and 12 v o w e l s  j e c t s were g i v e n p r a c t i c e as p o s s i b l e  and t o s e e i f  be o b t a i n e d f o r v o w e l s ,  e x p e r i m e n t s were c o n d u c t e d . ed i n t h e f i r s t  effects  i n t h e s e c o n d one.  i n repeating  t h e sounds  t o the e x p e r i m e n t a l c o n d i t i o n .  as  t e s t e d were f o u n d t o be r e p e a t e d f e w e r  times  DAF.  t h e s u b j e c t s were t r a i n e d  conditions  a t s i x sounds  (1958) s u b j e c t s ) , sounds in  at three  the l a s t  were u s e d  per second  sounds  per second  the s u b j e c t .  become f a s t e r  DAF.  (mean r a t e  I t was  under  the behaviour of a s p e c i f i p  under  auditory  Realizing  speech t h e need  articulator f o r such a study,  t o DAF, were r e q u i r e d  three  at zero delay  investi-  Subjects,  t o repeat the  a CVC month", i n w h i c h  / were embedded.  times each  fast  subjects  (1971) d e s i g n e d an e x p e r i m e n t t o  "that's  clicks  p o i n t had n o t i n v e s t i -  naive with respect  / e / and  Loud  differences  a s p e c t s o f DAF b e h a v i o u r .  phrase  of subjects  expected that  gate such s p e c i f i c  carrier  Chase's  groups.  gated  Sussman and S m i t h  SAF  to repeat  DAF and s l o w  r e s e a r c h e r s up t o t h i s  delay.  of  above).  However, no s i g n i f i c a n t  were f o u n d between t h e two The  trained  half  under  (mean r a t e  and t h e o t h e r h a l f  t o pace  slower under  t o r e p e a t sounds  two e x p e r i m e n t s d e s c r i b e d  s u b j e c t s would  / i / ,  quickly  Again  A f u r t h e r e x p e r i m e n t was d e s i g n e d i n w h i c h of  Sub-  the vowels  The p h r a s e s were r e p e a t e d and a t f o u r m a g n i t u d e s  of  -  delay.  Jaw  the vowels d i d not  graphic  condition. records  s u b j e c t s were r e c o r d e d  by  means  transducer.  R e s u l t s were as  of delay  -  movements o f t h e  of a strain-gauge  for  17  follows:  extent  of  change s i g n i f i c a n t l y  However, v i s u a l  jaw as  opening  a function  i n s p e c t i o n of  the  revealed  "a s l i g h t , b u t r a t h e r c o n s i s t e n t , i n c r e a s e i n jaw l o w e r i n g u n d e r t h e 300 msec d e l a y f o r / e / and /ae/ v o w e l c o n t e x t s " ( i b i d . , p. 6 8 9 ) . Duration  of  jaw  activity  f o r each vowel c o n t e x t  ficantly  l o n g e r under the  100-msec c o n d i t i o n .  durations at a l l values  o f d e l a y were r e c o r d e d  / i /  a delay  vowel sentence.  again  At  of  approached d u r a t i o n s recorded  O p e n i n g and slightly  closing  c h a n g e d as  velocity  of  jaw  400  under  statistically  significant,  and  /ae/ was  g r e a t e s t at the  jaw  closing  velocity  jaw  zero  for  the  activity  delay. only  However,  though  velocity  3 00-msec d e l a y .  as w e l l was  longest  movements was  opening  signi-  The  msec, jaw  a f u n c t i o n of delay.  not  was  greatest at  for  For  /ae /  300  msec  /e/  the delay.  "The c h a r a c t e r i s t i c a l l y g r e a t e r c l o s u r e v e l o c i t y d u r i n g t h e open v o w e l c o n t e x t was e v i d e n t o n l y f o r t h e n o r m a l and 100 msec d e l a y c o n d i t i o n s . Though t h e r e was a t e n d e n c y f o r jaw c l o s u r e v e l o c i t i e s t o i n c r e a s e as a f u n c t i o n o f v o w e l o p e n n e s s , the a u d i t o r y delay a l t e r e d the r e l a t i v e v e l o c i t y r e l a t i o n s h i p s of opening to c l o s i n g jaw movements, s u c h t h a t jaw o p e n i n g v e l o c i t i e s were g r e a t e r u n d e r d e l a y e d f e e d b a c k c o n d i t i o n s as compared t o jaw c l o s i n g v e l o c i t i e s . " ( i b i d . , p. 6 9 0 ) . Recently  another  a t t e m p t was  made a t  speech r a t e to maximally d i s t u r b i n g d e l a y .  relating  Robinson  (1972)  -  controlled  speech  jects  required to  were  rate  18  by  -  providing external pacing.  count  aloud  f l a s h e s of  Sub-  lights  and  were " c a r e f u l l y i n s t r u c t e d to enunciate each number c l e a r l y and e v e n l y and t o t r y t o make t h e n u m b e r l a s t a s l o n g a s t h e l i g h t s t a y e d on" ( i b i d . , p. 2 ) . Five  series  different was  of  flash  constant,  series  50  the  f l a s h e s were  rates.  and  subject heard delays  ed  frequency  to  SPL  the  accompanied  entire sis a  Within  beginning  different  were  the  experiment  presented  own  voice  delayed.  A  white-noise  human  speech  feedback  to  mask  c o n s i s t e d of  counting  articulatory  s c o r i n g system  i n which  each  ial  error  score  tween  speech  duced  a maximum  while  a  rate  three. and  a  faster  speech  is  approximately  of  of  was  The  a  at  a  of  each  Five  about  errors number  found.  errors  21  rate  restrict-  60  during  dB the  conduction.  significant  produced  rate.  according had  a  longer  slower  articulation  score  be-  delay  speech  number  of  to  potent-  interaction A  maximum  Analy-  pro-  rate errors  function  linear.  Discussion  Obviously, DAF  A  delay  number  shorter delay  at  2.3  of  spoken  eight  spectrum  signal  bone  of  flash  number  auditory  i n order  the  flash  used. of  series  each  with  his  band  each  at  experimenters  could  be  repeated  not  are  a l l of  the  i n agreement.  faster  under  DAF,  results Chase yet  obtained found  by  that  F l e t c h e r and  the [b]  Yates  -  found  their  s u b j e c t s were  fewer  times  under  as  a  result  Neither  of  speech  Fairbanks  multiple  Kozhevnikov  did  not  find  universal would  turbance ings  be  employed  that  have  discrepancies experimental  200-msec  Can  Huggins  of  of  attempt  review and  be  and  of  jaw  a  movement  the  dis-  contradictory  i n terms  of  find-  levels, measures  interpretation  r e s o l v e some o f  o f . some p e r t i n e n t a s p e c t s  of  in  maximal  playback  to  the  Smith  produced  Fairbanks'  made  did.  subjects  subject variability, even  will  the  value  seemingly  shift'  Robinson  Sussman  different  inherent or  the  'peak  encountered  a l l aspects  these  analysis,  design  whereas  delay  on  a  sounds  underlying  the  of  assumptions  of  experimenters.  been be  shown an  produced delayed However, menters feedback by  nor  speech  find  characteristic  i n terms  in a  Amount  to  Guttman  p r e d i c t e d by  instruction,  An  not  changes,  effect  functions.  i n the  did  single  C h i s t o v i c h study.  the  been  MacKay  so  disruptive  results?  the  and  explained  subject  of  and  -  repeating  rate  repetitions  the  as  DAF.  19  by  Chase  important by  DAF,  feedback as such  (1955)  amplification and  as  i . e . , with signal,  Black  the  degree  increasing  increases  (1955)  has  (1951)  held  limiters,  delayed  (1962),  i n the  approximately  volume  of  Guilfoyle  variable  Fairbanks  signal  employing  banks  of  of  disturbance of  i n disturbance  the  constant whereas  out,  the  of  occur.  the  earphones  others,such  vocal  the  some e x p e r i -  intensity at  has  others,  intensity  pointed  h i m s e l f , a m p l i f i e d the  among  signal  output  by  as a  Fair-  -  specified lifier.  amount by a d j u s t i n g I f volume l i m i t e r s  intensity  would r e s u l t  back s i n c e by  20 -  a r e used,  delayed  o f t h e volume  amp-  an i n c r e a s e i n v o c a l  i n a higher l e v e l  the amplified  the setting  the gain of the playback  of undelayed  feed-  s i g n a l w o u l d be l i m i t e d  limiter.  In such  a  system  acoustic  segments w i t h a h i g h e r i n t r i n s i c  intensity are  possibly  less  than  tic  s u b j e c t t o DAF i n t e r f e r e n c e  segments w i t h a l o w e r  event,  as F a i r b a n k s  intrinsic  the response  of  t h e volume l i m i t e r w o u l d m i n i m i z e  c a n be e x p e c t e d ,  on t h e o t h e r hand, v o c a l  ified  amount and no c e i l i n g  back s i g n a l , linearly ficulty  then v o c a l  related i n this  system  hold  levels,  above m e n t i o n e d of  signal  exists  i n finding  high  pain  thres-  the tape.  o f t h e s e c o n s i d e r a t i o n s c a n any o f t h e conflicting  results  be e x p l a i n e d i n t e r m s  h i s s i g n a l by a s much a s F l e t c h e r  this  imply  Chase d i d n o t ampand Y a t e s .  the subject with a lesser  available  t o him w i l l  'stutter'  long?  The q u e s t i o n w i l l  speech  p r o d u c t i o n and DAF i n t e r f e r e n c e  Kozhevnikov  feed-  The d i f -  a setting  o u t p u t by a p p r o a c h i n g  lify  feedback  by a s p e c -  i s approximately  intensity.  t y p e and amount o f a m p l i f i c a t i o n ?  that  setting  nonlinearities.  i s amplified  intensity  o r n o t t o overmodulate  In view  nonlinearities  a very high  any s u c h  acous-  I n any  p l a c e d on t h e a m p l i f i e d  output  vocal  though  output  t o feedback  enough n o t t o l i m i t  intensity.  (1955, p . 337) p o i n t e d o u t ,  of  If,  those  Does  amount o f d e l a y e d rather  than  pro-  be d i s c u s s e d b e l o w i n t e r m s o f  and C h i s t o v i c h  kept  mechanisms.  the l e v e l  o f t h e feedback  - 21-  signal  c o n s t a n t a t the earphones,  high'setting  that  subjects  any u n d e l a y e d a u d i t o r y Kozhevnikov ple  ed  f e e d b a c k a v a i l a b l e t o them.  r e p e t i t i o n s i n terms 1  themselves explained  o f the high  subject  level  performed under  f e e d b a c k n o t much l o w e r t h a n t h a t  Kozhevnikov ple  and C h i s t o v i c h  repetitions.  planation  of feedback. a level  employed  points  of delay-  i n the  Huggins,  suggested that  o f f e r i n g an a l t e r n a t i v e  perhaps  such a s o l u t i o n i s even  less  speakers of Russian per-  likely  Y e t , he  bf the lack  remains  t o be t e s t e d .  that in  Huggins  s e t a d o p t e d by t h e s u b j e c t s , purpose o f the experiment?  multiple in  jects  because  usually  resist  hypothesis w i l l underlying  Huggins  r e p e t i t i o n s , both  and C h i s t o v i c h i . e . , does  Huggins  assumptions  the subject  could  i sthe know t h e arrived  produce  such  y e t had n o t e n c o u n t e r e d them  seems t o be s u g g e s t i n g t h a t  producing multiple  be d e b a t e d  studies  a p p e a r s t o have  he h i m s e l f  repetitions at w i l l ,  h i s subjects.  a r r i v e d a t the conclusion  cause o f m u l t i p l e  and K o z h e v n i k o v  at t h i s conclusion  signal.  o f d a t a , however, s u c h a h y p o t h e s i s  t h e most l i k e l y  t h e Chase,  remarks  than the s o l u t i o n  b a s e d on t h e d i f f e r e n t i n t e n s i t i e s o f t h e f e e d b a c k In v i e w  multi-  o u t , t h i s type o f ex-  form d i f f e r e n t l y from s p e a k e r s o f E n g l i s h . that  the m u l t i -  study but d i d not produce  As H u g g i n s  i s inadequate.  explanation,  such a  c a n n o t be e x p e c t e d t o have had  and C h i s t o v i c h  However, H u g g i n s  but they used  further  repetitions.  i n a discussion  subThis  of the  of the experimenters.  Before proceeding with t h i s discussion,  one f u r t h e r  -  possible in  the  explanation  i t has  mentioned  frequent  multiple  C h i s t o v i c h study  n o t been c o n s i d e r e d  thus  responsible  -  f o r the  K o z h e v n i k o v and  Although  22  f a r , the  artificial  by  repetitions  suggests the  itself.  experimenters  palate could  have been  i n t h a t i t e l i m i n a t e d a p o r t i o n of the  feedback,  thus  available  f o r c o n t r o l and  'uncontrolled Lee  reducing  the  undelayed neural  tactile  feedback  c a u s i n g what F a i r b a n k s  termed  oscillations'. conceived  the  s p e e c h mechanism as  being  "somewhat l i k e a m a c h i n e gun, r e p e a t i n g a u r a l l y m o n i t o r e d u n i t s as l o n g as t h e t r i g g e r i s h e l d down" (Lee, 1951, p. 5 4 ) . He  suggested  the  t h a t the  syllable,  remarking  t i o n s were n o t itoring  was  tic  tactile  and  a u r a l l y monitored u n i t  t h a t D A F - i n d u c e d phoneme  observed.  is  repeti-  However, phoneme-by-phoneme mon-  hypothesized  Black  probably  by  Lee  to take  place v i a  kinesthe-  channels. similarly  considered  " t h a t the d u r a t i o n of the s y l l a b l e may have an i m p o r t a n t b e a r i n g upon t h e e f f e c t s o f d e l a y e d s i d e - t o n e " ( B l a c k , 1951, p. 5 8 ) . The  hypothesis  msec by  was  b a s e d on  (approximately  Black's  the  time.  Due  reading  time w i t h  to the an  Black d i d not exclude a monitored u n i t  fact  t h a t the  d u r a t i o n of the  s u b j e c t s u n d e r DAF)  reading  be  the  delay  syllables  r e s u l t e d i n the  of  180  produced  longest  disproportionate increase in  increase i n delay the p o s s i b i l i t y as w e l l .  f r o m 30  t h a t the  t o 60  msec,  phoneme  may  -  Both different  23  -  authors a r r i v e d  observations.  Lee's  at s i m i l a r hypotheses  nature of the d i s t u r b a n c e i t s e l f , his  c o n c l u s i o n s by  magnitude of  system,  selective  to these hypotheses an a s s u m p t i o n  to the r e l e a s e of the next  " f e e d s back  affects  and  tends to c i r c u l a t e  signals  "changes  themselves" Fairbanks,  relationship val  and  that  (ibid.,  to  one  o u t p u t and  remarks  (Fairbanks,  t h e o r y , he  of  to  feedback  aspects of the  disturbing  that  speech  p.  possible  delay  output  interunits  t h e d a t a a r e meager,  d i s t u r b a n c e ...  1955,  each  588).  between t h e m a x i m a l l y  cycle  such t h a t  o r more t i m e s due  of v o c a l  p.  con-  unit"(Chase,1958,  commenting on t h e i d e a o f a  "the c r i t e r i o n  cybernetic a closed  speech  the d u r a t i o n of c o n v e n t i o n a l speech  established"  at  each  t o t h e s p e a k e r and  i n the p h y s i c a l  s u c h as t h e s y l l a b l e , and  by C h a s e :  the m o n i t o r i n g system  the temporal d i s c r e p a n c i e s signal  delay intervals  reiterated  tributes  speech u n i t  the  i s a u n i t - b y - u n i t mon-  speech u n i t  5 8 4 ) . DAF  on  whereas B l a c k a r r i v e d  produced  p.  are based  disturbance.  Basic itoring  relating  conclusions v i a  342).  i s not y e t  Influenced  by  c o n c e i v e d of the speaking system  system:  "A c l o s e d c y c l e s y s t e m , o r s e r v o s y s t e m ... employs f e e d b a c k o f t h e o u t p u t t o t h e p l a c e of c o n t r o l , comparison of the o u t p u t t o t h e i n p u t , and s u c h m a n i p u l a t i o n o f t h e o u t p u t - p r o d u c i n g d e v i c e as w i l l c a u s e t h e o u t p u t t o have t h e same f u n c t i o n a l f o r m as t h e i n p u t " ( F a i r b a n k s , 1954, p . 1 3 5 ) .  as  -  One p a r t  o f the system  feedback  signals  signals  nal,  i s a comparator which r e c e i v e s  as w e l l  are c a l c u l a t e d  a mixer.  This  24 -  as t h e i n p u t .  and s e n t  which i s then  error  Here t h e e r r o r  t o an e f f e c t o r  sent  to the e f f e c t o r  s i g n a l may  travel  to modify  the e r r o r  several  signal  loop being p r o g r e s s i v e l y  until  An i m p o r t a n t  i t equals  zero.  s t o r a g e component w h i c h r e c e i v e s  tor.  I t i s able  will  reach  started  zero.  before  effector  to calculate  referring not  signal  does n o t have t o w a i t Fairbanks  suggested  to the u n i t  be i d e n t i f i e d  the proi s zero.  part input  reduced  o f the system i s f r o m t h e compara-  the time a t which the e r r o r  The n e x t u n i t  the error  sig-  t i m e s a r o u n d t h e com-  parator-mixer-effector  a  unit v i a  mixer determines the e f f e c t i v e d r i v i n g  cess o f speech p r o d u c t i o n u n t i l The  the  of input reaches  can t h e r e f o r e zero,  so t h a t the  f o r a new d r i v i n g  that  the u n i t  of speech p r o d u c t i o n  w i t h any c o n v e n t i o n a l  be  signal.  of control, control,  linguistic  should units.  " I t seems more l i k e l y t h a t t h e u n i t o f c o n t r o l , although r e l a t e d t o such u n i t s , i s more f u n d a m e n t a l , and t h a t i t may c o n s i s t , a t any g i v e n t i m e , o f one o r a number of such c o n v e n t i o n a l u n i t s , or of a f r a c t i o n of the smallest phonetic u n i t . " ( F a i r b a n k s , 1955, p . 3 4 2 ) . He r e f e r r e d  to the u n i t  as a  "semiperiodic, r e l a t i v e l y long, a r t i c u latory cycle, with a correlated cycle o f o u t p u t . " ( F a i r b a n k s , 1954, p . 1 3 8 ) . Under DAF a t any g i v e n units  time d e l a y ,  w h i c h have p e r i o d s  d e l a y m i g h t be i n f e r r e d  t h e number o f c o n t r o l  critically f r o m t h e DAF  related  t o the time  functions.  -  Consistent succeeding vious  with  25 -  t h e above model i n w h i c h  segment d e p e n d s on t h e f e e d b a c k  one, F a i r b a n k s  and Guttman  is  the fact  in  their  tions  that predominatly  data.  Thus, they  and c o n s i d e r  from t h e p r e -  (1958) p r e s e n t  o f t h e DAF i n t e r f e r e n c e mechanism.  each  their  view  Pertinent to their  model  double r e p e t i t i o n s occurred  only  account  f o r double  repeti-  that the occasional multiple r e p e t i t i o n s  are "uncommon ... p e r s o n - l i n k e d , and g i v e t h e impression o f w i l d and u n c o n t r o l l e d o s c i l lation o f t h e v o c a l mechanism" ( i b i d . , p. 2 0 ) . Fairbanks DAF  and Guttman s u g g e s t t h a t t h e p r i m a r y f o r m o f  disturbance  a r e r e p e t i t i o n s , w h i c h a r e d e s c r i b e d as  "automatic responses t o misinformation  i n the feedback  complex"  automatically re-  (ibid.,  p. 1 9 ) .  A repetition  s u l t s when t h e s u b j e c t p r o d u c e d A during storing not  B, t h u s t r i g g e r i n g  segments A and B and h e a r d  another  B and t e m p o r a r i l y r e -  normal feedback r e l a t i o n s h i p s .  aperiodic, subjects  I f t h e s y s t e m were  w o u l d be e x p e c t e d  t o produce  A B B C C D D e t c . u n d e r DAF c o n d i t i o n s . A s i m i l a r mechanism o f DAF i n t e r f e r e n c e i s p r o p o s e d by H u g g i n s , w h i c h d o e s , however, t r y t o a c c o u n t f o r multiple the  repetitions.  Huggins suggests  t h a t DAF c a u s e s  c o n t r o l mechanism t o l o s e i t s ' p l a c e '  i n which case instruction (Huggins,  "the t a r g e t a r t i c u l a t i o n  i s continued  1968, p . 5 9 ) .  until  i n t h e program,  of the previous  the place  i s re-found"  I f the c o n t r o l finds i t s place  -  from  undelayed  sources  conducted) , then on  26  -  o f feedback  only a s l i g h t  ( e i t h e r n e u r a l o r bone-  lengthening occurs.  t h e o t h e r hand, t h e p l a c e i s f o u n d  auditory  feedback  inserted  into  to the delay" such and  rapid  "then  an e x t r a segment may be sequence, w i t h  (ibid.,  A necessary  p. 59).  i s probably delayed  signal,  a slower  source,  the promised cover  occur.  companion paper  "which a r t i c u l a t o r y  tions"  (ibid.,  in a  I f the place i s re-found from  the delayed  Huggins has n o t y e t p u b l i s h e d i n w h i c h he w o u l d t r y t o d i s -  sequences generate  1968, p . 5 9 ) .  remains u n t e s t e d  equal  o f the produced  which can o n l y occur  sequence o f a r t i c u l a t i o n  drawling w i l l  duration  conditionfor  the s i m i l a r i t y  sequence o f a r t i c u l a t i o n s .  during  the delayed  the a r t i c u l a t o r y  insertion monitored  source,  from  If,  most  Thus, t h e above  repeti-  hypothesis  to date.  K o z h e v n i k o v and C h i s t o v i c h v i e w e d  the DAF-induced  r e p e t i t i o n s as w e l l as t h e p r o l o n g a t i o n s , r e g a r d l e s s o f the c o n d i t i o n s which determine induced  disturbances w i l l  phenomenon. and  occur,  They d i s a g r e e d w i t h  Guttman t h a t s p e e c h  with  w h i c h one o f t h e s e as b a s i c a l l y  t h e same  the c o n c l u s i o n of Fairbanks  production units  any known l i n g u i s t i c  DAF-  units.  do  It i s this  not c o i n c i d e disagreement  which prompted K o z h e v n i k o v and C h i s t o v i c h t o c a r r y o u t their  own DAF i n v e s t i g a t i o n s .  viously,  As h a s b e e n s t a t e d p r e -  K o z h e v n i k o v and C h i s t o v i c h d i d n o t f i n d m u l t i p l e  repetitions most c l e a r l y  uncommon, expressed  i n fact effect  they  found  them t o be t h e  o f DAF i n t h e i r  data.  -  C l e a r l y , these  27  -  r e p e t i t i o n s h a d t o be a c c o u n t e d f o r i n a n  e x p l a n a t i o n o f DAF i n t e r f e r e n c e . K o z h e v n i k o v and C h i s t o v i c h , l i k e F a i r b a n k s  and  Guttman, found r e p e t i t i o n s o f l o n g e r u n i t s o c c u r i n g frequently a t longer delays. ed  f r a g m e n t s were e x t r e m e l y  Did the fact that the repeatv a r i e d necessitate the conclu-  s i o n t h a t speech u n i t s should of the c o n v e n t i o n a l  more  n o t be i d e n t i f i e d w i t h any  linguistic  units?  K o z h e v n i k o v and  C h i s t o v i c h argue t h a t because o f the v a r i a b i l i t y o f fragments nothing  c a n b e known f r o m t h e s e  repetitions.  F u r t h e r m o r e , m u l t i p l e r e p e t i t i o n s were a t times on r e p e t i t i o n s o f l o n g e r authors  to consider  these  superimposed  f r a g m e n t s , w h i c h caused t h e above  t h a t t h e e f f e c t s may be o f a d i f f e r e n t  nature. Rejecting Fairbanks'  a s s u m p t i o n s , K o z h e v n i k o v and  C h i s t o v i c h proposed t h e f o l l o w i n g model: matic  a c t i v i t y o f t h e nervous centers which c o n t r o l the  a n t a g o n i s t i c muscles o f the l i p s , a C V - s y l l a b l e i s formed. excludes  ing closing-opening  the auditory  chords  feedback  I n t h i s model t h e p e r i o d o f f l u c t u a t movements a s a r e s u l t o f DAF w o u l d be  d e t e r m i n e d by t h e a c t i v i t y  by  Delaying  tongue, and v o c a l  temporarily the c o n t r o l l i n g influences of the high-  er nervous centers.  and  through the auto-  n o t by t h e d e l a y t h e above a u t h o r s  o f the nervous centers  interval.  S u c h a m o d e l was  themselves derived  f r o m a number o f o b s e r v a t i o n s :  the  f r e q u e n t l y o b s e r v e d l a c k o f c o o r d i n a t i o n between v o c a l fold activity  a n d a r t i c u l a t i o n was c o n s i d e r e d  evidence f o r  -  DAF-induced of  28  fluctuations in parallelly  antagonistic muscles.  was  deduced  into  CV  these one  from  authors  cohesive  necessary more  the  structures  same  -  to  complex  unit  That  DAF  occurs  transformation  (on  the  basis  i n the  consider  combinations  CV  at  the  their  CCV  higher  that  of  of  hypothesized,  operating  CCV  CCV  are  research  constitute  Thus, are  level  structures  structures  centers).  as  reflex  previous  structures  such  a  centers  i t became  basic  while  made u p  of  CV  complexes " o r g a n i z e d s o t h a t t h e f o l l o w i n g complex begins before the preceding one i s a b l e t o f i n i s h . " (Kozhevnikov C h i s t o v i c h , 1965, p. 158). Further  confirmation  unit  was  from  C  provided  to  finding  V  that  but  only  jaw  tated  by  delay,  seems  to  further  (Sussman  and  Kozhevnikov a  E n g l i s h are  obtained are  level  basic  to  under  DAF  fact  from  V  have  syllable  that  to  C.  velocity  though, not  strictly  their  and  the  phonological  that  of  that  assumption  production  closing  was  slowed,  findings to  I t must and with  be  DAF  absence  system  the  they  the  of  speaker  results  results  and  operates  Chistovich at  movements can  higher would  the  considered  Smith  i f Kozhevnikov  that  Smith's  hypothesis;  Sussman  temporary of  and  observed  facili-  opening-closing and  was  even  their  that  cohesive  times  above  comparable  However,  the  at jaw  related  a  slowing  was  the  the  as  Sussman  velocity  not  no  C h i s t o v i c h model).  speech in  open  substantiate  Russian.  correct in  reflex  the  on  the  whereas  and  the  opening  Smith  possibility,  on  by  of  and  be  a are  studied  control, not  be  a  then  -  crucial  follows  stitutes time in  -  aspect. Accepting  it  29  of  that  the  r e p e t i t i o n of  preservation existence  delay,  i t  CV-syllable  of  of a  the  the  a  same  same  structure  as  cohesive open  syllable  structure. grew w i t h  structure,  Since  an  conthe  increase  was  "necessary to c o n s i d e r t h a t the essence o f t h e e f f e c t o f t h e d e l a y o f an a c o u s t i c a l s i g n a l c o n s i s t s not of the calling o f r e p e a t e d movements but i n the delay o f t h e t r a n s i t i o n f r o m one s t r u c t u r e o f movements t o a n o t h e r . A c t u a l l y , i n the case of a delay of the a c o u s t i c a l s i g n a l man can a r b i t r a r i l y e i t h e r s t u t t e r o r draw o u t t h e s p e e c h . I f he h u r r i e s , stuttering occurs; i f he t r i e s t o s p e a k slowly, the speech i s drawn out. Howe v e r , r e g a r d l e s s o f w h a t he d o e s , the change of s t r u c t u r e s i s slowed and t h e time occupied by the pronunciation of the phrase i n c r e a s e s . " (this author's e m p h a s i s ) ( K o z h e v n i k o v and Chistovich, 1965, p. 155). Crucial Chistovich ure  (number  delay  the  of  the  fact  study  f i n d i n g which in  he  not  the  above  advanced  are  one  of  within  the  the  in  not  a  of  that  with  hypothesis, of  in  his that  prolongation,  was  of  a  related of  delay  with  the  to  multiple i t is  related  and  interval,  In  re-  view  of  repetitions  crucial  not  the  repeated  multiple  findings.  and  struct-  Kozhevnikov  the  r e p e t i t i o n s , and  r e p e t i t i o n s be  Kozhevnikov  durations the  to  along  by  existence  series)  related  considered  multiple  multiple  time  states  agreement  expression  proposed  repetitions  were  petitions  length  that  Huggins  in multiple  Chistovich  theory  repetitions  interval.  segments  a  is  to  each to  the  that  the  segment delay  -  30  -  interval. The F l e t c h e r and the  seeming c o n t r a d i c t i o n of the Chase, Yates s t u d i e s might now  former study, s u b j e c t s  i n the  and  be c o n s i d e r e d .  exhibited multiple  l a t t e r they s l i g h t l y prolonged.  In  repetitions;  Huggins' model  would p r e d i c t t h a t the behaviour of Chase's s u b j e c t s  was  governed by the delayed source of feedback, whereas the j e c t s i n the F l e t c h e r and feedback.  reducing  Yates study r e l i e d on undelayed  However, F l e t c h e r and  ed, a m p l i f i e d the  Yates, as has  Huggins' model of  undelayed feedback a l s o i n c l u d e s n e u r a l have to assume t h a t the F l e t c h e r and e n t i r e l y on n e u r a l  feedback.  d i f f e r e n c e i n the two  feedback.  We  Yates s u b j e c t s  Does t h i s imply an  would  relied  inherent  sets of s u b j e c t s , or does i t imply  l e v e l of delayed feedback causes s u b j e c t s  r e l y more on n e u r a l used a very high  feedback?  Kozhevnikov and  high number of s u b j e c t s  In view of the  i n the F l e t c h e r and  three experiments, i n h e r e n t  to  Chistovich  l e v e l of feedback, y e t t h e i r s u b j e c t s  formed l i k e the Chase s u b j e c t s .  all  been mention-  feedback s i g n a l more than Chase, thus  p o s s i b l e undelayed feedback.  t h a t a higher  sub-  per-  unusually  Yates study i n  between-subject d i f f e r e n c e s  does not appear to be a reasonable e x p l a n a t i o n  either.  Huggins, as mentioned p r e v i o u s l y , b e l i e v e d t h a t the s e t a s u b j e c t adopts i s r e s p o n s i b l e He  mentioned  as one  for multiple  repetitions.  s u b j e c t knowledge of the purpose of the  possible explanation.  i n s t r u c t i o n to the s u b j e c t  I t cannot be d i s p u t e d  influences his attitude.  study  that Chase  -  stressed appears  accuracy to  multiple desired that  be  repetitions behaviour  control.  Fairbanks  since  subjects trol.  then to  could  of  has  lose  (1950a)  exposure  to  be  either  accepts  the  of  repetition  the  structure  and i n  repeating  ure,  either  transition  the one  fast to  shed,  nothing  sider  the  two  strives  to  to  assume  without repetitions  and  to  for  fight  Chistovich It  control,  a loss  out,  physically  previous with  hypothesis  constitutes  Chase,  the  confronted  multiple  also  unable  the  'uncontrolled'.  pointed  DAF i s  is  reasonable  termed m u l t i p l e  expected  resist  this  a behaviour  meant by  Huggins  more  folthat  of  con-  than  two  tiring.  A  subject  maintain control  or  willing  control.  essarily  of  that  and K o z h e v n i k o v  already  to  is  consitute  is  i n d e e d by  Despite  ing  It  as  subjects  believe  study?  had a l r e a d y  what  possible,  normally,  each system normally  As Lee  minutes  the  it  they  oscillations'  made m o r e e x p l i c i t lows,  unless  in  Is  that,  repetitions  'uncontrolled  -  and s p e e d .  implying,  multiple  31  contradictory  of  Kozhevnikov  the  and Yates  structure, slow,  did  not  c a n be known f r o m t h e  s u c h as  subjects  [b]  and  [d]  constitutes the  of  same  this  need to  results.  in  be  rapid  slow-  structure  task  in  the  consisted  one  slowing.  would  one  Chistovich,  experiments  constitutes  nec-  If  required  repetition  a new s t r u c t u r e  the  of  Because the  Fletcher  or  and  and p r o l o n g a t i o n  not  results.  same s t r u c t u r e  slowing.  case where  structures  of  d i s c u s s i o n , we a r e  struct-  Since be Let  a  accomplius  asked to  conrepeat  alternation,  - 32 -  it  b e i n g u n d e r s t o o d t h a t an e p e n t h e t i c v o w e l c o u l d be  o f e a c h s t r u c t u r e , as i t i s d i f f i c u l t s o u n d w i t h o u t s u c h an  insertion.  part  t o say t h e speech  The h y p o t h e s i s o f  K o z h e v n i k o v and C h i s t o v i c h w o u l d p r e d i c t t h e f o l l o w i n g r e sults:  t h e s u b j e c t s i n t h e Chase s t u d y would have p r o d u c e d  rapidly  [bbbbdddd]  but not  [bdbdbd]; whereas the s u b j e c t s i n t h e F l e t c h e r  (any number, d e p e n d i n g on t h e d e l a y ) ,  Y a t e s s t u d y would have p r o d u c e d  and  [b" b" b d" d" d b" b" b d" d d ] 1  1  1  1  1  1  1  n  w h e r e an e p e n t h e t i c v o w e l  (at the release of the closure)  c o u l d a l s o be p r o l o n g e d .  Under a s e r i e s o f d e l a y s t h e  rel-  a t i v e number o f r e p e t i t i o n s o f a s t r u c t u r e p r o d u c e d by t h e f o r m e r s e t o f s u b j e c t s w o u l d be r e l a t e d t o t h e  relative  amount o f p r o l o n g a t i o n e x h i b i t e d by t h e l a t t e r  s e t o f sub-  jects.  Only i f t h e Chase s u b j e c t s would produce  [bdbd] i n  r a p i d s u c c e s s i o n c o u l d t h e r e s u l t s o f t h e s t u d i e s be c o n sidered  contradictory. Why  some s u b j e c t s p r e d o m i n a n t l y e x h i b i t one  type  o f s l o w i n g b e h a v i o u r and o t h e r s u b j e c t s t h e o t h e r , o r w h a t d e t e r m i n e s t h e o c c u r r e n c e o f b o t h b e h a v i o u r s i n one a t d i f f e r e n t t i m e s must r e m a i n l a r g e l y  speculation  subject until  more i s known a b o u t t h e s e b e h a v i o u r s t h e m s e l v e s , u n t i l i n t e r a c t i o n c a n be more p r e c i s e l y d e s c r i b e d and u n t i l  their we  know more a b o u t t h e r e l a t i o n o f t h e s e b e h a v i o u r s t o n o r m a l r a t e o f s p e e c h and a b o u t r a t e o f s p e e c h  itself.  R o b i n s o n c o n c e i v e d t i m i n g i n s p e e c h as b e i n g p e n d e n t on t h e s p e e c h i t s e l f determined rhythm.  as o p p o s e d  to a  de-  biologically  He i n t e r p r e t e d h i s f i n d i n g s as e v i d e n c e  -  for  such a model.  find  As p o i n t e d  a peak s h i f t  DAF.  their  MacKay o n l y  r e s u l t s are not s t r i c t l y "striking  t o d e c i d e when a q u a v e r  As  was a l r e a d y speaking  foreseen  r e p e t i t i o n took p l a c e  m i g h t be n e c e s s a r y  T h u s , many a c t u a l p r o l o n g a t i o n s Robinson's e r r o r  MacKay, h a v i n g  to  rate  discovered  subjects  rate,  suggested  view  that  Robinson's  some  reservations.  subjects  with  with a  tendency  a faster rate of their  d i f f e r e n t mechanisms f o r t h e u n d e r DAF.  r a t e u n d e r DAF must t h e n be v i e w e d n o t a s a  change b u t as a t r a d i n g  another, keeping  i n mind  rate  number o f r e p e t i t i o n s w i t h  n o r m a l s p e e c h r a t e u n d e r SAF and p r o l o n g a t i o n  rate  units,  included i n  v o l u n t a r i l y decreasing  u n d e r DAF showed a d e c r e a s e d  Altering  specifi-  to reveal i f  o f s p e e c h showed a g r e a t e r  s p e e c h , whereas s u b j e c t s  system  r e p e t i t i o n s might  function with  s t u t t e r u n d e r DAF t h a n  decreasing  are possibly  One must t h e r e f o r e  a r t i c u l a t i o n score  (Robin-  (Chase, 1958, p . 5 8 9 ) .  c o u n t and many a c t u a l  have been m i s s e d .  also  and when i t i s n o t .  about r e p e t i t i o n s o f phoneme-sized  an  s l o w e r maximum  Robinson  by C h a s e , a l t h o u g h he was  speech r e c o r d i n g  linear  omissions,  such a s c o r i n g  i s striking  a graphic actual  including  a vowel" as e r r o r with  under  r e p e t i t i o n s as  comparable.  The d i f f i c u l t y  is  MacKay d i d n o t  change i n r a t e  counted  quavers w i t h i n  1972, p. 2 ) .  cally  with  and R o b i n s o n c o u n t e d a l l e r r o r s ,  tallied son,  out e a r l i e r ,  f o r disturbance  However, s i n c e  errors  33 -  that  true  o f one t y p e o f s l o w i n g f o r the previously  established  framework i n w h i c h r e p e t i t i o n s a r e s e e n a s s l o w i n g  of the  -  transition  from  one  i n one  slowing  occurred  i n the  other  two  forms of s l o w i n g  any  one  in  the  type  SAF  Why  -  s t r u c t u r e to the  increase  time.  34  behaviour  next.  Thus, w i t h  (prolongation) a  (repetition). are mutually  I t appears  that  the at  a s l o w maximum s p e e c h  c o n d i t i o n s h o u l d e x h i b i t more o f be  decrease  e x c l u s i v e behaviours  subjects with  slowing cannot  an  e x p l a i n e d on  the  rate  repetitive  the b a s i s of the  data  available. In view of the  above c o n s i d e r a t i o n s one  seriously  reconsider Fairbanks'  iculatory  error  primary  form  (substitution,  o f DAF  i n t e r a c t i o n of the analysis must be fects  of l o c a l  types  local  omission,  repetition)  of slowing  behaviour,  In a d d i t i o n ,  as w e l l as u n d e r DAF  rate assessed.  I f slower  can be  shown t o e x h i b i t d i f f e r e n t  slowed  r a t e u n d e r SAF  can  and  patterns  (1973) has  pointed out  and  from  as  opposed  (ibid.,  p.  speech  determinants there  are  biochemical c o n s t r a i n t s t h a t are  not  under the c o n t r o l  interaction  duration  ef-  DAF  that "although  p h o n o l o g i c a l l e n g t h are the major  neuromuscular  The  the  t h e n MacKay's h y p o t h e s i s p o s t u l a t i n g  o f most s e g m e n t a l d u r a t i o n "  entirely  rate  be s u b s t a n t i a t e d .  Allen rate  fine  global  and  d i f f e r e n t mechanisms f o r r a t e c h a n g e s u n d e r SAF t o DAF  the  a  rate-under  slowing  art-  i s the  In o r d e r t o a s s e s s  r a t e i s needed.  v a r i e d u n d e r SAF  on  (1955) s u g g e s t i o n t h a t  disturbance. two  must  222),  of the h i g h e r nervous c e n t e r s .  between p h o n o l o g i c a l l e n g t h and  i s complex.  A l l e n ' s diagrammatic  phonetic  speech  production  -  model c o n t a i n s  a structured  output b u f f e r .  The  -  35  phonological  output b u f f e r provides  a speech motor c o n t r o l program determines p a r t l y the ests  t h a t when we  variability  due  lated  a statistical  attempts of the  and  model t o  separate  level, clock  o p e r a t e on  patterns,  the  the  ( n e u r o m u s c u l a r and  bio-  only  He  proposes  components.  i f the  speaker  repeated  (the  production  r a t e of  the  influence  (i.e.,  specifically  a greater  ment d u r a t i o n s  when a l o c a l  decrease  repeated utterance  of  segments). the  at  this  timing DAF-slowed  would e x h i b i t  variability the  c o n t r o l and  predicts  stressed  program?  and  clock)  i f i t i s assumed t h a t  DAF  production  segmental  although perhaps g r e a t e r  when i t e s c a p e s t h e  (during  speech  a slower rate)  s l o w e d whenever i t comes u n d e r DAF  place  the  iso-  motor c o n t r o l  speech  determines the  e x p e c t e d u n d e r DAF  Allen  can  c o n t r o l takes place  i s v o l u n t a r i l y set to  similar  sugg-  be  f i x e d i n the  segmental t i m i n g  (DAF  which  Allen  these variance  applied  for  control error in  f i t into Allen's  v o l u n t a r i l y slowed  speech  be  does DAF  Does DAF the  input  utterance.  How model?  be  an  system,  measurement e r r o r ) .  t o keep h i s r a t e  same  the  (speech r a t e v a r i a t i o n )  However, t h i s m o d e l c a n  Since  output of  from p e r i p h e r a l v a r i a b i l i t y  chemical constraints  the  movements.  segmental t i m i n g  motor c o n t r o l p r o g r a m  into  (transfer function)  articulator  measure t h e  to  input  clock  is  speeds  up  after a  pause).  variability in clock  A l t h o u g h he  same p h r a s e k e e p i n g  can  rate  of  seg-  takes  refers the  rate  to  -  constant, ed  i t should  segments d u r i n g  36 -  a l s o be t r u e voluntarily  assumed t h a t , i n b o t h c a s e s , clock  takes  differ one  place, provided  DAF o p e r a t e s  and  linear  increases  undelayed  c u l a r moment. of  sounds  be  explained  operates  i n duration  c o n t r o l a t t h e motor itself  i s slowed  o f segments r e s u l t ,  a l l the time.  pro-  I t has a l r e a d y  t h e speech  con-  been  production  feedback a v a i l a b l e t o the speaker a t a p a r t i Furthermore,  i t i s known t h a t c e r t a i n  a r e more a f f e c t e d .  by a s l o w i n g  of the neural  This  clock.  at a level  program, i . e . t h e r e f l e x  types  fact  cannot  I f DAF  on manner o f a r t i c u l a t i o n ,  t o assume t h a t DAF i n t e r f e r e s w i t h  o f t h e commands  i t is  the execution  below t h a t o f t h e motor c o n t r o l  level  p r o p o s e d by K o z h e v n i k o v and  (1965).  P e r h a p s DAF i s a c t i v e o n l y addition  that  f r o m one s e c o n d t o t h e n e x t b u t v a r i e s  selectively  Chistovich  timing  However,  even i f such a c l o c k e x i s t s ,  (continuants)  reasonable  of  o f t h e segmental  t h e r a t e o f t h e c l o c k does n o t  t h a t DAF d o e s n o t a f f e c t  t h e same e x t e n t  with  speech i f i t i s  such t h a t the c l o c k  DAF i s e f f e c t i v e  mentioned to  slowing  on s e g m e n t a l t i m i n g  programme l e v e l  vided  slowed  t o o much f r o m one c o n d i t i o n t o t h e o t h e r .  c a n n o t be c e r t a i n ,  trol  i n a comparison o f s t r e s s -  i n t e r f e r e s with  segment d u r a t i o n s  u n d e r DAF s h o u l d  at this  segmental t i m i n g  under v o l u n t a r i l y  provide  level  or i n  control.  Study  a l t e r e d r a t e and  some i n s i g h t s i n t o t h e s e  questions.  Chapter AIMS  In  the  a  normal  speaker's of  THE  speech As  rate  and  under  been  have  of  speech  d i s t u r b a n c e s based  the  role  past.  of  to  review  to  of  of  the  stuttering  Although sis,  new  better  i t remains  be  (1968) t o be DAF  it  clear  whether  other how  rate  of  terms,  do  they  which  those are  are  speech  i f they  at  slowed  a  also  Riper  out  i f the  from  as  could  production  a  to  and an  phenomenon. i t relates  (1972,  pp.  382-403).  detailed  analy-  patterns his subjects true,  patterns are  SAF  global  DAF-induced  possibly  such  DAF  analysis  pathological  universally  differ  of  i n f o r m a t i o n as  carried  under  a very  detailed speech  but  i n van  these  of  of  well  as  and  furthermore,  typical under  voluntarily  of  a  DAF.  slowed  In speech,  differ?  The late  into  as  tested  under  part  a more  DAF  found  displayed  slower  on  stuttering  can  to  segments  2), measures  understanding  insights  available  Huggins  i s not  most  a u d i t o r y feedback,  understanding A  A  speech  a voluntarily  (Chapter  f o r the  i n the  only  speech,  shown  been  acoustic  i s designed  DAF.  nature  not  research study  durations of  has  disturbance  lead  INVESTIGATION  general, this  investigate  rate  OF  3  experiment  aspects  of  specific  to  reported here  the  temporal  DAF.  -  37  -  i s designed  patterning  of  to  iso-  speech  - 38 -  Specifically,  the following  h y p o t h e s e s w i l l be  tested: (a)  When s p e e c h i s s l o w e d v o l u n t a r i l y sounds  below  speech a t a normal than consonants.  (b)  indicates  that  r a t e , vowels  The p i l o t  i n comparison  W i t h i n the class -of vowels, ;  a r e p r o l o n g e d more t h a n open v o w e l s .  close Within  of consonants, continuants are prolonged  more t h a n  obstruents.  When s p e e c h i s s l o w e d  study  prolonged lable  t h a t open v o w e l s  and w i t h i n  speech under  the p i l o t  slowed  durational  slowed  a f f e c t s the  SAF i s compared as i n d i c a t e d  speech under  i n which  and p o s s i b l y v o w e l  increases.  the s y l -  class.  speech under  study, that  openness  sound  DAF, i t i s e v i d e n t ,  lows an o r d e r l y p a t t e r n vowel  The p i l o t  and f r i c a t i v e s a r e  the sentence s e l e c t i v e l y  i n c r e a s e s o f each  When v o l u n t a r i l y  by  o f DAF, n o t a l l  t h e most and t h a t p o s i t i o n w i t h i n  durational  with  as a r e s u l t  a r e p r o l o n g e d by t h e same amount. indicates  With  a r e p r o l o n g e d more  the c l a s s  sounds  (c)  SAF, n o t a l l  a r e p r o l o n g e d by t h e same amount.  study reported  vowels  under  SAF f o l -  stress,  degree o f  length  determine  On t h e o t h e r hand,  durational  i n c r e a s e s due t o DAF a r e d e t e r m i n e d by a r t i c u l a t o r y parameters articulated ness .  s u c h as v o i c i n g , sequence  as w e l l  closure,  position  i n the  as d e g r e e o f v o w e l  open-  4  Chapter  EXPERIMENTAL APPARATUS AND 4.1  Subjects One  five  female s u b j e c t served  f e m a l e and  their  five  ages r a n g e d  university  male s u b j e c t s s e r v e d  from  Audiology  F i v e m a l e and naive with  two  21  to  and  i n the The  The  requirements  25 dB  as d e f i n e d by  pure tones  of f r e q u e n c i e s  disturbance  under  (pilot rate the  study  and  then  and  longest  fields  or  of  Medicine. were  s u b j e c t and  been b r i e f l y  the  exposed  selection  as  subjects  air-conduction thresholds within the  ISO  Standard  250-4000 Hz,  and  of  1964  notable  the  a short connected  see A p p e n d i x B)  a t a slow r a t e .  again  the  i n the  study  f o r the  subject read  passage,  reading  condition  A l l s u b j e c t s were  for speech  Design  pilot  subject read  220-,  study;  DAF.  Experimental The  and  past. two  0 dB  pilot  f e m a l e s u b j e c t s had  o f bone- and  4.2  years.  female s u b j e c t s i n the main study  were e v i d e n c e of  32  study  i n the main  Speech S c i e n c e ,  r e s p e c t t o DAF.  three remaining DAF  i n the p i l o t  undergraduates or graduates  Linguistics,  to  PROCEDURES  F o l l o w i n g those  same p a s s a g e u n d e r DAF  a t 200-msec d e l a y . time  u n d e r SAF  was  The  at  instructed  - . 39  -  at a two  normal  readings,  200-,  180-,  delay producing  chosen f o r a n a l y s i s .  s u b j e c t was  passage  to read  For the  the  the SAF  passage  -  at  40 -  h e r n o r m a l r a t e and t h e n  t i o n s were g i v e n For was s c r e e n e d General within  t h e main s t u d y ,  the hearing  specified  novelty effects.  u n d e r DAF o v e r  Subjects  then  errors,  Subjects  phones v a r i e d w i t h  the v o c a l output  ined of  total  a stop watch.  time  the female subjects  a t the earThe  while  s l o w down and  as p o s s i b l e .  o f e a c h s u b j e c t was d e t e r m -  passage t o the nearest  half  In a d d i t i o n , a r t i c u l a t o r y  Each i n s t a n c e o f e r r o r ,  independent a r t i c u l a t o r y  jects  t h e passage  the experiment.  were n o t t o a l t e r n a t e l y  was t a b u l a t e d a s one e r r o r . an  instructed  n o t t o change s t r a t e g i e s  reading  I f the  of the subjects.  as n a t u r a l l y  pass-  f o r t h e SAF and DAF c o n d i t i o n s , t i m i n g t h e d u r a t i o n  the recorded  ed.  read  level  s e t t i n g was u s e d t h r o u g h o u t  but t o t r y t o read The  were  f o r t h e male  The sound p r e s s u r e  i . e . , they  a short  The r a n g e ' f o r  was 150-240 msec.  s p e e d up  they  then  s u b j e c t s was 200-310 msec; t h e r a n g e  reading,  read  s e e A p p e n d i x C) u n d e r SAF.  a range o f d e l a y s .  S u b j e c t s were i n s t r u c t e d  fell  p r a c t i s e d r e a d i n g u n d e r DAF t o  the passage again.  same p l a y b a c k  of a l l subjects  above.  subjects f i r s t  (screening passage,  read  inctruc-  i f subjects' thresholds  s u b j e c t s made any a r t i c u l a t o r y to  No  a t the A u d i o v e s t i b u l a r U n i t o f the Vancouver  the l i m i t s  exclude  i t slowly.  f o r t h e DAF c o n d i t i o n s .  Hospital to establish  The  age  t o read  a second  e r r o r s were  with count-  r e g a r d l e s s o f length or type, A second observer e r r o r count  f o r the purpose o f checking  c a r r i e d out  on h a l f  reliability  t h e sub-  o f measure-  -  ment.  In t h e i r  more t h a n one The  two  each  -  c o u n t t h e two  e r r o r on any  m e a s u r e s and  subject  41  observers  d i d not d i f f e r  of the i n d i v i d u a l e r r o r  by  scores.  t h e f o l l o w i n g r a t i o were p l o t t e d f o r  as a f u n c t i o n o f  delay:  DAF T o t a l D u r a t i o n C o r r e c t Words Ratio  = SAF  The  delay  a t which  cular  subject  was  t o be  employed  passage  the highest chosen  They  ratio  for that  i n the main  Subjects experiment.  Total Duration T o t a l Words  returned  four (a)  as d e l a y  on a s u b s e q u e n t  were r e q u i r e d  partivalue  to read  day  f o r t h e main  a short  see Appendix  connected D)  i n the  conditions: (Condition under  (b)  subject  for a  experiment.  (main e x p e r i m e n t p a s s a g e ,  following  occurred  SAF  (Condition under  SAF  I) a t a normal  rate  (NORMAL);  II) a t a v o l u n t a r i l y slowed  rate  (SLOW S A F ) ; (c)  (Condition III) under  DAF  subject) paces (d)  DAF  f o r that  a t a slow r a t e , such t h a t  the s u b j e c t  (Condition under  (at the s e l e c t e d delay  (SLOW  the  DAF  DAF);  IV) ( a t t h e same d e l a y  a maximum r a t e  (FAST  DAF).  as above) a t  -  The tions was  42 -  SAF c o n d i t i o n s  i n t h e above o r d e r .  always  four  s e n t e n c e s , each  (main e x p e r i m e n t  subject.  t h e f o u r above t a s k s ,  d u r e was r e p e a t e d , b u t t h i s read  t h e DAF c o n d i -  The o r d e r o f t h e DAF c o n d i t i o n s  r e v e r s e d f o r every second Following  preceded  time  i n an i d e n t i c a l  sentences, see Appendix  c o n t a i n e d p r e d o m i n a n t l y open back v o w e l s  E).  (/o/ s e n t e n c e ) , one  f r o n t vowels  ( / i / sentence),  c o n t a i n e d p r e d o m i n a n t l y open f r o n t v o w e l s  and  one c o n t a i n e d p r e d o m i n a n t l y The f o u r  frame  One s e n t e n c e  one  sentence).  proce-  t h e s u b j e c t was a s k e d t o  embedded  contained predominantly close  the entire  c l o s e back  (/a/ s e n t e n c e ) ,  vowels  (/u/  s e n t e n c e s were p r e s e n t e d i n random  order. Subject  i n s t r u c t i o n s were m i n i m a l  S u b j e c t s were t o l d , their  speech  f o r t h e SLOW c o n d i t i o n ,  by p r o d u c i n g l o n g e r p a u s e s  to prolong the a c t u a l  and i n f o r m a l . n o t t o slow  between w o r d s , b u t  u t t e r a n c e s and t o t r y t o m a i n t a i n t h e  same s p e e d  throughout.  ice  I f t h e s u b j e c t was p e r f o r m i n g i n t h e r e q u i r e d  this.  manner, no f u r t h e r If  a subject  practised, DAF  or  d i d n o t p e r f o r m t h e t a s k as i n s t r u c t e d  condition  to repeat the task.  task. and as  F o r t h e SLOW  t h e s u b j e c t was g i v e n a d e m o n s t r a t i o n by t h e o f what was meant b y :  " c a t c h up w i t h y o u " .  j e c t s were t o l d not t o omit  to pract-  i n s t r u c t i o n s were g i v e n f o r t h i s  he was a s k e d  experimenter  S u b j e c t s were t h e n a s k e d  F o r t h e FAST DAF c o n d i t i o n  t o r e a d as r a p i d l y  any w o r d s .  " L e t t h e DAF p a c e y o u "  as p o s s i b l e  sub-  and t o t r y  -  4.3  Instrumentation The  43 -  and A r r a n g e m e n t  s y s t e m employed  s y n c h r o n o u s and d e l a y e d  i n the production of the  feedback  c o n s i s t e d o f a Uher  phone M o d e l M516, a K o r t i n g C o n s t e l l a t i o n 1/4-track  tape  that  f o r DAF e x p e r i m e n t a t i o n ,  a i r c o n d u c t e d synchronous feedback  ded.  The v o c a l o u t p u t  second  tape  88 M o d e l MT 3644  r e c o r d e r w i t h movable p l a y b a c k  earphones designed  recorder  was r e c o r d e d  ( S c u l l y Model  micro-  heads, and  namely  such  i s maximally  simultaneously  occluon a  280-2) v i a an A l t e c 681  A LO m i c r o p h o n e . The  s u b j e c t was s e a t e d  f o u r t o s i x i n c h e s from t h e  m i c r o p h o n e s i n an IAC 1204 s o u n d p r o o f  room.  The t a p e  r e c o r d e r s were o u t s i d e t h e s o u n d p r o o f  room.  The o p e r a t o r  was  able t o observe  window a n d m o n i t o r e d  the s u b j e c t s through t h e s u b j e c t ' s speech SOUNDPROOF  SCULLY TAPE RECORDER  a double-glass continuously. ROOM  ALTEC IN  IN  MIKE  UHER MIKE  KORTING TAPE RECORDER OUT  Figure  4.1. B l o c k d i a g r a m o f i n s t r u m e n t a t i o n f o r the d e l a y e d  feedback  producing  and f o r r e c o r d i n g .  -  4.4  tape.  Recordings  were made on  7.5  per  The  inches  recording  approximately recorder. the  0 dB  The  level  as  level  c h o s e n was  108  pure tone recorded  Korting  tape  played  setting,  recorder.  b a c k on  level  the  Scully  tape  recorder  meter of  the  K o r t i n g tape  dB  SPL  a t the  was  K o r t i n g tape  was  at a  of  a t 0 VU  level  tape  t h e VU  a t the  b a c k on  a Bruel  and  B r u e l and  the  at 0  at the  e a r p h o n e s was  2203 P r e c i s i o n Sound L e v e l M e t e r and  the  recorder  recorded  recorder  m e a s u r e d on  was  e a r p h o n e s when  played  When w h i t e n o i s e  the  the playback  Sound p r e s s u r e  on  recorders  Ampex 631 p r o f e s s i o n a l  r e g i s t e r e d on  playback  setting  both  s e c o n d on  a 1-kHz  was  -  Calibration  speed of  at  44  VU  same  95 dB  SPL.  Kjaer  Type  Kjaer  Arti-  3 ficial  Ear  (Type 4152)  The  precise delays  were e s t a b l i s h e d as tion.  head.  microphone.  A  recorded  was  the  a 6 cm on  sharp  a t 7.5  click  damped.  The  repeatedly The  per  from the  p r o c e d u r e was  The  playback  from c l i c k  along  path  close  microphone  earphones u n t i l  repeated  head.  onset  d i s t a n c e was  the  posi-  f o r ten  t o f o u r t h echo o n s e t The  was  click  different  made f o r e a c h s e t t i n g  four.  the  picked  the  Mingograms o f t h e  d i v i d e d by  of to  The  i t s e c h o s were t h e n  i n msec.  fastened  head  second.  click  distance  playback  at the microphone  of the  the  the  recorder  produced  positions and  K o r t i n g tape  e a r p h o n e s were p l a c e d  click  inches  coupler.  the  a f u n c t i o n of  A m i l l i m e t e r s c a l e was  the playback  up  with  initial and measured  delay  -  45  -  d u r a t i o n s so o b t a i n e d were p l o t t e d as a f u n c t i o n of p l a y back head p o s i t i o n was  approximately  (in millimeters).  The d e l a y f u n c t i o n  l i n e a r and d i s t a n c e v a l u e s a l o n g the  s c a l e c o u l d be c o n v e r t e d t o d e l a y v a l u e s from t h i s graph.  . Chapter 5 ANALYSIS  5.1  OF DATA  Instrumentation Mingograms were made o f t h e t a p e r e c o r d e d s p e e c h ,  displaying  the f o l l o w i n g  Channel  Figure the  5.1  four  signals:  1  s p e e c h wave  signal  2  duplex  3  fundamental  4  l o g of average  oscillogram f r e q u e n c y o f s p e e c h wave speech  power  shows a s c h e m a t i c o f t h e s e t up u s e d  to  produce  mingograms.  DUPLEX OSCILLOGRAPH'  TRANSPITCHMETER  TAPE RECORDER  0SCILL0MINK  SPEECHPOWERMETER  Figure  5.1.  Block diagram produce  o f i n s t r u m e n t a t i o n used t o  mingograms.  -  46 -  -  The REVOX M o d e l vided or  tape  recorder  A77.  power  developed  circuit  above  four  oscillogram  t o Channels  yielded  because  were  t h e most  msec.  described  5.2  Segmentation  vowel or  onset The  In these  and ending  criteria  phones  5.2).  was p r e c e d e d  /v/.  involved  utilizing  basis  f o r segment-  are converted to a  In addition,  duration system  spectrograms  factor  calculated  from  the spectrograms  used  i n this  study i s  F.  by comparison  or followed cases,  spectrograms  be d i s c u s s e d  were  by / l / ,  used  could  of a l l four  Some d i f f i c u l t i e s  of formants  will  t o t h e one  The d u p l e x  the boundaries o f vowels  determined  Figure  intensity  Criteria  Vowels:  (see  segmented  and a s c a l e  The t r a n s c r i p t i o n  accurately  then  curve.  segment  i n Appendix  similar  pro-  (1961).  effective  w e r e made o n a K a y S o n a g r a p h  into  4) w a s  the higher frequencies  convert acoustic  2 a n d 3 was  on t h e mingograms.  intensity  s e t u p was a  t r a n s p i t c h m e t e r . ' The  (Channel  utterances traces  negative-going  to  i n t h e above  by P e t e r s o n and McKinney Speech  ation  used  The i n p u t  by a Frcfikjaer-Jensen  speech  the  47 -  be  traces  encountered  / r / , /w/, w e r e made  i n the ambiguities.  i f  the  / j / , /&/, and t h e  as segmentation  below  fairly  cues.  f o r the individual  -  48  -  F i g u r e 5.2. Mingogram of p a r t of t h e phrase / g r i d i  V/l/:  timz/.  t h e momentary d e c r e a s e i n energy between  a vowel and the f o l l o w i n g / l / r e f l e c t e d by a d i p i n the average speech power t r a c e , as w e l l as changes i n formant p a t t e r n s on s p e c t r o g r a m s , were used t o d e t e r m i n e the o n s e t of / l / .  I f t h e p r o n u n c i a t i o n was as f o l l o w s :  /fuel/,  the / e / was c o n s i d e r e d as p a r t o f the / l / , because / e / was not p a r t o f the o t h e r o c c u r e n c e s o f / u / , whereas i n some i n s t a n c e s o f /!/ a / a / preceded the /!/,  i.e.,i n /pipl/.  -  F i g u r e 5.3.  49  -  Mingogram of the p h r a s e  V/r/  and /&"/:  Segmentation  /fuls/.  of / r / a f t e r a  c o u l d u s u a l l y be made on t h e b a s i s o f s p e c t r o g r a m s . i t i o n was  c o n s i d e r e d p a r t of the vowel, making  more r e l i a b l e .  /&/  vowel Trans-  segmentation  o c c u r r e d o n l y a f t e r a consonant  and  was  t h u s e a s i l y s e g m e n t e d on t h e b a s i s o f a b r u p t c h a n g e s on  the  mingograms. Initial  / j / ,  /l/»  / r / , /w/:  The  ending of these  p h o n e s c o u l d be c o n s i s t e n t l y d e t e r m i n e d by a c h a n g e i n t h e d u p l e x o s c i l l o g r a m t r a c e as i l l u s t r a t e d  i n Figure  5.4.  - 50 -  F i g u r e 5.4. Mingograms o f t h e p h r a s e s /&/ and / v / :  /WAI-/,  A A ft/, and / j u z / .  Both a change i n t h e d u p l e x o s c i l l o -  gram t r a c e and absence o f vowel formants on spectrograms were used as segmentation c r i t e r i a  ( F i g u r e 5.5).  -  Figure  5.5.  Mingogram o f  Nasals: the  onset  display trace.  5.2,  and  of  the  the  nasals  doubt,  nasals  regular  Jaft/.  were d e t e r m i n e d by  pattern  which  nasals  and d u p l e x o s c i l l o g r a m were made,  c o u l d be e a s i l y d i s c e r n e d  on w h i c h t h e  (see  Figures  5.4).  c o u l d be d e t e r m i n e d f a i r l y oscillogram  trace  junction with of  / Sa  spectrograms  Stop consonants:  ation  phrase  s p e e c h wave t r a c e  In case of  formants  -  Boundaries of  and e n d i n g o f  on t h e  51  the  beginning  Beginning  and e n d o f  accurately  from the  (negative-going  closure  for  duplex  i n t e n s i t y curve)  s p e e c h wave t r a c e . of  plosion  i n con-  However, d e t e r m i n -  initial  stop  consonants  -  proved  extremely  registered ation  difficult  preceded  The these  ing  i n some c a s e s where no  a t the onset o f the c l o s u r e the c l o s u r e .  made i n some c a s e s  of  52 -  Arbitrary  Segment R e j e c t i o n  articulation,  the boundaries  curve  on t h e d u p l e x  ( s e e F i g u r e s 5.2, 5.3, 5.4 and 5 . 5 ) .  Criteria  When segments were added of  these  t o the expected  segments were n o t u s e d  son o f segment d u r a t i o n s a c r o s s c o n d i t i o n s ; comparative  analysis  d e s c r i b e d i n Chapter  segments were sometimes t h e r e s u l t the  following  (underlined part  and  t h e added  o c c u r r e n c e o f t h e segment and r e j e c t  when one r e p e t i t i o n articulated,  of a correction  as i n  (underlined  produced  word  / s i 6e t r i e 8ri/, teams . . . " . of the text  segments):  " . . . awesome hawk's  segment was t h e r e s u l t  u n d e r DAF, t h e f o l l o w i n g  analysis  added  segments were a d d e d , n o t p a r t  / DsgemvhDks / , t h e s e q u e n c e If  Such  "... see t h e t h r e e greedy  unrelated to the text  compari-  i . e . , i n the  s e q u e n c e ) was r e p e a t e d c o r r e c t l y :  o f t h e sequence  sequence  in a  6.  e x a m p l e , where an i n c o r r e c t l y  Sometimes e x t r a  h a d t o be  were d e f i n e d a s t h e b e g i n n i n g and e n d -  of the negative-going i n t e n s i t y  5.3  decisions  /f,s/Z,J,^,9,h/:  fricatives:  trace  and a pause o r i n h a l -  ( s e e F i g u r e 5.2, 5.4 a n d 5 . 5 ) .  fricatives  oscillogram  energy  criteria  were u s e d  f o r purposes  of repetition t o s e l e c t one  o f the comparative  the other occurrence or occurrences: i n a series  generally  with  of repetitions  a non-reduced  was  vowel,  correctly  even  though  -  p e r h a p s d r a w l e d , and t h e incorrectly  53  -  other  repetitions  a r t i c u l a t e d v e r s i o n s of the  were r e d u c e d  intended  sequence  of. a r t i c u l a t i o n , e i t h e r  i n terms o f vowel q u a l i t y or  ing  linguistic  error  rectly ted  o r some o t h e r  articulated  f o r the  comparative  examples)  / pabasasasas / If  the  the  i n t e n d e d a r t i c u l a t o r y s e q u e n c e was a n a l y s i s and t h e  r e p e t i t i o n or m i s a r t i c u l a t i o n following  feature error,  /grididi/  / gakakakahazasas I  repeated  /  repeated  sequence,  Figure  f o r the  the  one  o f r e p e t i t i o n were a r t i c u l a t e d c o r r e c t l y i n  power t r a c e was s e l e c t e d  selec-  (castle).  sequences o f segments i n  sequence w i t h the  cor-  (greedy),  instance  the  voic-  the  ( u n d e r l i n e d segments i n  discarded:  (passes),  rest of  or  highest  each  speech  comparative a n a l y s i s  (see  5.6).  Figure 5.6.  Mingogram o f the  s e q u e n c e / PAjdAbAbAbAb. 5a  /.  -  If  54  -  o n l y one a c o u s t i c segment was r e p e a t e d  times c o r r e c t l y the  l a s t occurrence of the  for  analysis.  the  comparative  segment was  The maximum e r r o r w h i c h may r e s u l t rejection repeated the  c r i t e r i a was e s t i m a t e d most f r e q u e n t l y  longest  sum o f t h e  alternative  tic  u n d e r D A F , as  segments.  the  sum o f t h e  shortest (subject  chosen  above  two s u b j e c t s ,  who  sum o f  was d i v i d e d by  w h i c h were n o t i n v o l v e d  In the w o r s t case  o r amounted t o 10%.  from the  follows:  a c o u s t i c segments  a c o u s t i c segments  ambiguities plus the  for the  both  alternative 1)  the  in acous-  the e r r o r  fact-  Chapter 6 RESULTS AND DISCUSSION The  r e s u l t s o f t h i s study w i l l be r e p o r t e d and d i s -  cussed s i m u l t a n e o u s l y  i n t h i s chapter.  T h i s mode o f p r e -  s e n t a t i o n was chosen because o f the complex nature o f the results.  The p i l o t study, the s c r e e n i n g study, t h e main  experiment, and the summary and c o n c l u s i o n s a r e presented i n 6.1, 6.2, 6.3, and 6.4 r e s p e c t i v e l y . 6.1  Pilot  Study  The mingograms o f the recorded p i l o t study  pass-  age were segmented i n the manner d e s c r i b e d i n Chapter Ten phrases, beginning w i t h the second phrase  5.  i n the pass-  age  (Appendix B) were analyzed i n t h e NORMAL, SLOW SAF and  DAF  (200 msec only) c o n d i t i o n s . A n a l y s i s o f the a b s o l u t e d u r a t i o n s o f the a c o u s t i c  segments r e v e a l e d t h a t , compared t o the SLOW SAF c o n d i t i o n , (1)  vowels i n s t r e s s e d s y l l a b l e s , except  f o r the open  vowels /ae/ and /o/, were o f s h o r t e r a b s o l u t e d u r a t i o n i n the DAF c o n d i t i o n , the g r e a t e s t d i f f e r e n c e being observable (2)  open vowels were o f longer a b s o l u t e d u r a t i o n i n the DAF  (3)  i n the c l o s e f r o n t vowels;  c o n d i t i o n , regardless of s t r e s s ;  f r i c a t i v e s and v o i c e d stops were o f longer a b s o l u t e d u r a t i o n i n the DAF c o n d i t i o n , ' t h e g r e a t e s t d i f f e r e n c e occurring i n i n i t i a l  position;  - 55 -  -  (4)  voiceless the in  DAF  those  syllables'  Because  English  phonological  red  defined  was  difference  i n  occurring  only  with i n a  as vowel  i n a  s y l l a b l e  were  refer-  s y l l a b l e . i . e . ,  o f  the  each  i n t h e SLOW  segments  i nt h e  and  phrases,  segments  systematically  con-  t o t h e NORMAL  stressed  o f the analyzed  The acoustic  i n terms o f  conditions  o f the acoustic  i nt h e  SAF a n d DAF  stressed  as  phonological  reference  across  study  stress  t o English  i n t h e SLOW  compared  d i dn o t d i f f e r  conditions.  primary  n o t be defined  vowel  durations  o f the durations  phrase, DAF  rules  t o i n a l lconditions Total  sum  duration  i n the p i l o t  t o carry  could  i . e . ,a  condition  defined  according  stress  i t was  condition,  NORMAL  absolute  the greatest  expected  rules.  SAF  o f longer  were  SAF c o n d i t i o n ,  ditions,  -  p o s i t i o n .  syllables  NORMAL  were  condition,  f i n a l  'Stressed  stops  56  SAF and  normalized  as  follows:  -  where, the of  f o ra  r e l a t i v e  R D  "  D( eg) 2D(Seg) s  sentence  o r phrase  duration  o f a  an acoustic  segment  segment,  i n that  ZD(Seg)  i s t h e sum o f d u r a t i o n s  in  sentence  the an  that  r e l a t i v e utterance  o f phrase.  duration f o ra  i n v e s t i g a t i o n ,  D(Seg)  sentence  i s the  o r phrase,  o f t h e acoustic  B r i e f l y ,  i n percent  s p e c i f i c  under  o f a  condition.  RD  simply  c e r t a i n  RD i s  duration and  segments represents  segment i n  -  57  -  The so n o r m a l i z e d d a t a the  r e v e a l e d t h a t compared  to  NORMAL c o n d i t i o n ,  (1)  the v o w e l s were o f l o n g e r r e l a t i v e d u r a t i o n i n b o t h  (2)  the  SLOW SAF a n d DAF c o n d i t i o n s ;  the  s t o p s were o f s h o r t e r  the  SLOW SAF and DAF c o n d i t i o n s .  Compared t o t h e (1)  SLOW SAF c o n d i t i o n ,  vowels i n stressed /ae /  els in (2)  the  r e l a t i v e duration i n both  s y l l a b l e s , except  and / o / , w e r e o f s h o r t e r  f o r the  relative  open vow-  duration  DAF c o n d i t i o n ;  f r i c a t i v e s w e r e o f l o n g e r r e l a t i v e d u r a t i o n i n t h e DAF condition.  Graphs o f the  relative durations  t e r n s w h i c h were s i m i l a r ditions  f o r the  of s y l l a b l e s revealed  NORMAL and SLOW SAF c o n -  i n t h a t w o r d - and s e n t e n c e - s t r e s s c o r r e l a t e d  longer r e l a t i v e duration,  whereas  pat-  the p a t t e r n s  with  f o r t h e DAF  c o n d i t i o n w e r e u n l i k e t h o s e o f t h e NORMAL c o n d i t i o n i n final  s y l l a b l e s of the  duration regardless counted f o r the gardless  s e n t e n c e were o f l o n g e r  relative  o f s t r e s s and i n t h a t f r i c a t i v e s  stress.  In  summary,  p o s i t i o n i n the  t o be p a r a m e t e r s w h i c h d e t e r m i n e speech.  to d i f f e r  changes  at  Since the  de-  appear  a slower  In a d d i t i o n , v o l u n t a r i l y slowed speech from DAF-slowed s p e e c h .  re-  syllable, stress,  g r e e o f v o w e l o p e n n e s s a n d manner o f a r t i c u l a t i o n  of  ac-  longer r e l a t i v e duration of s y l l a b l e s  of  that  rate  appears  results  of  the  -  pilot  study  58 -  a r e b a s e d on t h e p e r f o r m a n c e o f one  speaker  only  and s i n c e no a t t e m p t was made t o c o n t r o l  DAF,  t h e y were c o n s i d e r e d m e r e l y h y p o t h e s e s t o be t e s t e d .  6. 2  Screening The  two  Study  two d i f f e r e n t  ranges o f d e l a y with which the  s e t s o f s u b j e c t s were p r e s e n t e d  basis that  of previous the delay  findings  producing  for at  ratio  tioned a lower  and S t r o m s t a ,  The g r a p h s o f t h e d u r -  described i n chapter  4, r e v e a l e d  on t h e i n t e r v a l  two h i g h v a l u e s , a s c a l c u l a t e d  index  of disturbance,  value.  1965) ,  maximum d i s t u r b a n c e was 180 msec  each s u b j e c t t h e r e o c c u r r e d least  h a d b e e n c h o s e n on t h e  (Mahaffey  f o r m a l e s and 270 msec f o r f e m a l e s . ation-error  r a t e under  The d e l a y  separated  producing  that  measured  by t h e above-menf r o m e a c h o t h e r by  the higher  o f t h e two  h i g h v a l u e s was s y s t e m a t i c a l l y c h o s e n a s t h e d e l a y i n g maximum d i s t u r b a n c e ) results delays be  a r e summarized producing  f o r t h e main experiment.  i n table  f o r females.  the highest value  The  average o f the delays producing  was  297 f o r f e m a l e s  The  As c a n be s e e n , t h e  the highest disturbance  s h o r t e r f o r males than  delays producing  I.  (produc-  fell  values  tended t o  The a v e r a g e o f t h e near  200 msec.  the second h i g h  value  a n d 206 f o r m a l e s .  O r d e r o f d e l a y p r e s e n t a t i o n may have i n f l u e n c e d which delay 3,  p r o d u c e d maximum d i s t u r b a n c e  4, and 5.  For these  u n d e r DAF p r o d u c e d  three  f o r male  subjects the f i r s t  t h e maximum d i s t u r b a n c e .  subjects  reading  No s u c h  order  -  Subjects  R e a d i n g Time i n seconds u n d e r SAF  59 -  D e l a y i n msec producing h i g h e s t peak disturbance  D e l a y i n msec producing the s e c o n d peak  Female subjects 1  25  250  290  2  (a)*  24  200  290  2  (b)  24  200  310  3  25.5  230  310  4  23.5  200  310  5  22.5  200  270  1  23 .5  240  200  2  28  240  170  3  21.5  170  220  4  28  180  240  5  29  170  200  '  Male subjects  *  f e m a l e s u b j e c t number 2 was r e c o r d e d t w i c e a t d i f f e r e n t times with the d e l a y s presented i n d i f f e r e n t orders t o c h e c k i f t h e m e a s u r e was r e l i a b l e .  Table  I.  N o r m a l r e a d i n g t i m e u n d e r SAF and d e l a y s p r o d u c i n g p e a k s o f d i s t u r b a n c e as d e f i n e d by t h e d u r a t i o n - e r r o r r a t i o d e s c r i b e d i n c h a p t e r 4.  -  60  -  e f f e c t s were o b s e r v e d  f o r the  remaining  subjects.  (1971) o b s e r v e d  order  effects  f o r females,  served  no  order  effects  f o r males.  screening  study  suggest  t h a t perhaps order  entirely  confined to Figure  for  the  three  6.1  The  Timmons  w h e r e a s she  results  of  the  effects  are  shows t h e r e l a t i v e  the main experiment.  As  j e c t s was  DAF  amount o f  disturbance  by  c a n be  seen,  to a very  each of the  different  differences.  s u b j e c t s , who  had  h i g h s c o r e s on  were more a f f e c t e d ality  Beaumont and  by  DAF.  extent.  Salter  (1973),  among o t h e r s ,  is  by  attention erial) DAF that  e.g.,  simultaneously  i s more d i f f i c u l t  will the  d i s r u p t the  i f either or  airconducted  speech l e s s .  for control  of  I n summary, t h e c o n f i r m the  Yates  demands  ( r e a d i n g mat-  (1965)  degree of  on  considerable individual  prose),  hypothesized  speech  disturb-  relies  the d i f f e r e n t  of t h i s  person-  opposed t o  speech t o d i f f e r i n g results  that  that  f o r normal c o n t r o l  rely  such  Zelniker  task  i s the e x t e n t t o which a speaker  a s s u m i n g t h a t some s p e a k e r s channels  task  (random words as  a u d i t o r y feedback  for  to which a subject  another  i f t h e DAF  f a c t o r which determines  a n c e u n d e r DAF  related  suggested  f a c t o r s determine the extent DAF,  Many  (1957) f o u n d  disturbance.  attentional affected  sub-  t e s t s of perseveration,  These authors  v a r i a b l e s t o d e g r e e o f DAF  (1971) and  Foss  in  three  h y p o t h e s e s have been o f f e r e d i n t h e p a s t t o a c c o u n t individual  not  females.  s u b j e c t s whose r e c o r d i n g s were a n a l y z e d  affected  ob-  of  on  speech,  feedback  extents.  p a r t of the  d i f f e r e n c e s which  study exist  F i g u r e 6.1.  DAF-induced speech d i s t u r b a n c e ( e r r o r - d u r a t i o n r a t i o ) f o r male s u b j e c t 1, and female s u b j e c t s 2 and 3.  -  in  r e a c t i o n t o DAF,  not  designed  interference the  results  that  the  in  and,  or  s u g g e s t , as  of  examined  are  t o be  the Main  the  jects  2 and  measured  The  f o r every  of  the  minus t h e  Figure  four  subjects.  the  duration  the  5).  to the 6.2  sentences  changes  listed  i n chapter  criteria  of  1 and  1 and  p a u s e s and rejection  shows t h e  i n the  four  from c o n d i t i o n to c o n d i t i o n .  the  same s p e a k i n g  the  absolute  ber  o f phonemes i n t h a t  durations  the  duration' duration rejected  0  'total  conditions  In o r d e r  to  throughout a d i v i d e d by  graphs r e v e a l e d  three subject  to evaluate  were g r a p h e d  (see  that  in  durations'  f o r the  from s u b j e c t  of each s y l l a b l e  The  total  was  criteria outlined  maintained  syllable  sub-  segment  minus t h e  average  varied  and  r a t e was  as  mingo-  condi-  female  'Total  5,  four  the  four  each a c o u s t i c  defined  'Total durations'  G f o r sample g r a p h s ) .  most  observed  segmented u t t e r a n c e .  (according  suggested,  explained.  f o r male s u b j e c t  of  chapter  i f the  units,  perhaps the  f o r male s u b j e c t  a s e n t e n c e o r p h r a s e was utterance  DAF  main experiment passage i n the  of  segments  nature of  main experiment s e n t e n c e s i n the  3.  was  Experiment  c o n d i t i o n s were segmented  t i o n s were segmented  study  speech p r o d u c t i o n  time r e l a t i o n s h i p s are  t h e mingograms o f  the  screening  about the  nature of  In accordance w i t h  grams o f  the  C h a s e e t a l . (1959) have  f a c t o r s t o be  Results  although  about the  s p e e c h u n d e r DAF  6.3  -  t o answer q u e s t i o n s  critical  important  62  if  sentence, the  num-  Appendix  subject  1  -  63 -  30,000 —  25,000 —  CONDITION  i  n  i  SUBJECT  Figure  6.2.  i I  i i r n i z SUBJECT  2  i  n  ur i z  SUBJECT  Average ' t o t a l d u r a t i o n s ' o f t h e main sentences i n the four c o n d i t i o n s .  3  experiment  - 64 -  tended  to maintain  ence, w h i l e  t h e same s p e a k i n g  subjects  2 and 3 t e n d e d  rate  throughout a  to increase  their  sentrate  t o w a r d s t h e end o f s e n t e n c e s i n t h e SLOW SAF a n d SLOW DAF conditions.  The ' t o t a l  passage r e v e a l e d  duration'  that during  o f each phrase  i n the  t h e SLOW SAF c o n d i t i o n  subject  1 t e n d e d t o s l o w down t o w a r d s t h e end o f t h e p a s s a g e . short, tions  the speaking  rates varied across  and a t t i m e s w i t h i n  al  spoke a t t h e i r maximum r a t e i n  FAST DAF c o n d i t i o n a s o p p o s e d t o s p e a k i n g r a t e i n t h e NORMAL c o n d i t i o n , i t w i l l  'total duration  1  and c o n d i -  conditions.  Although subjects the  subjects  In  f o r a l l subjects  at their  be n o t e d  norm-  that  u n d e r FAST DAF was g r e a t e r  t h a n i n t h e NORMAL c o n d i t i o n , e v e n t h o u g h no r e p e t i t i o n s o r other  additions t o the expected  were i n c l u d e d figure  duration' values  6.2. I f t h e d u r a t i o n s  to the ' t o t a l bits  i n the ' t o t a l  duration'  slowing  than  h e r e f o r two r e a s o n s . duration  ratio  disturbance obtained  subject,  subject  1 exhi-  u n d e r DAF and s u b j e c t  subject Firstly,  as a r e l i a b l e  as p l o t t e d i n  o f t h e r e p e t i t i o n s a r e added  f o r each  by f a r t h e most s l o w i n g  b i t s more  sequence o f a r t i c u l a t i o n  3.  These f a c t s a r e mentioned  the data  support  the error-  i n d i c a t o r o f degree o f speech  p r o d u c e d by DAF i n t h a t  t h e same r e s u l t s  by t h e e r r o r - d u r a t i o n r a t i o .  Secondly,  o f t h e same phenomenon,  were  the data  seem t o i n d i c a t e t h a t r e p e t i t i o n s and p r o l o n g a t i o n deed m a n i f e s t a t i o n s  2 exhi-  namely  are i n slowing:  s u b j e c t s who u n d e r FAST DAF do n o t make many r e p e t i t i o n s do n o t p r o l o n g  very  much.  This  does n o t answer why a  -  repetition merely  a t one t i m e and d r a w l i n g  suggests the s i m i l a r i t y  subject 6.3^  occurs  65 -  a t another, i t  o f t h e e f f e c t s i n terms o f  reaction.  Relative The  study.  Durations  d a t a were n o r m a l i z e d  as d e s c r i b e d  The r e l a t i o n s h i p s o f ' s t r e s s e d '  long  i n the p i l o t  vowels as d e -  3 fined long  below u n d e r 6.3 , v o w e l s o t h e r vowels  figure  ('other'vowels)  , a n d c o n s o n a n t s a r e shown i n  6.3 f o r t h e m a i n e x p e r i m e n t s e n t e n c e s  conditions.  crease  i n relative  crease.  duration  No c o n s i s t e n t  'other'vowels  change i n r e l a t i v e  / a / and / £ / f r o m c o n d i t i o n  the  other  other  duration  conditions,  to increase  i n t h e FAST DAF c o n d i t i o n .  to i n t o de-  duration  to condition.  / o / tended  conditions,/u/  tended  and consonants tended  for  duration  i n the four  As c a n be s e e n , i n c o m p a r i s o n w i t h t h e NORMAL  c o n d i t i o n , vowels, p r i m a r i l y  the  than t h e 'stressed'  occurred  Compared t o i n relative  In comparison  consistently increased  with  i n relative  i n t h e SLOW SAF c o n d i t i o n . A d i s c u s s i o n o f these r e s u l t s , which a r e e s s e n t i -  ally  t h e same a s t h e r e s u l t s o f t h e d a t a a n a l y s i s  below, w i l l and  f o l l o w when t h e l a t t e r  r e s u l t s are reported  discussed.  2 6.3  Relative The  described  Change M e a s u r e  d a t a were a l s o n o r m a l i z e d  as f o l l o w s :  -  NORM- S SAF S DAF F DAF  Figure  6.3.  66 -  NORM. S SAF S DAF F DAF  NORM. S SAF S DAF F DAF  R e l a t i o n s h i p o f ' s t r e s s e d ' long vowels, 'other' vowels, and c o n s o n a n t s i n t h e m a i n e x p e r i m e n t s e n t e n c e s i n t h e four conditions.  -  R CL R  (k) (  K  - < > V ~ SD(I) TD (k) S D  )  k  for a particular  crease  o r decrease  the is  T  D  (  I  )  A  where,  a particular  67 -  segment,  RC(k) i s t h e r e l a t i v e i n -  i n d u r a t i o n o f an a c o u s t i c  segment i n  c o n d i t i o n k ( I I , I I I , o r IV) w i t h  respect to  corresponding  segment  i n t h e NORMAL c o n d i t i o n ,  t h e d u r a t i o n o f t h e a c o u s t i c segment u n d e r c o n d i t i o n k,  and  TD(k) i s t h e ' t o t a l d u r a t i o n '  measure r e f l e c t s tion  the r e l a t i v e  u n d e r c o n d i t i o n k.  increase o r decrease  o f a n a c o u s t i c segment compared  NORMAL c o n d i t i o n and n o r m a l i z e d responding  'total  durations'.  ponds t o no c h a n g e , a n RC v a l u e to a r e l a t i v e  decrease.  be u s e d h e r e a f t e r t o r e f e r crease  with  An RC v a l u e greater  Any will  refer  levels  to levels  t h a n 1.0 c o r r e s -  o r 'decrease'  will  i n c r e a s e o r de-  formula.  from t h e a n a l y s i s o f t h e  f o u r main e x p e r i m e n t s e n t e n c e s w i l l s e t s o f phones  t o t h e two c o r -  o f 1.0 c o r r e s -  less  to the relative  obtained  i n the  t h a n 1.0 c o r r e s p o n d s  'Increase'  c a l c u l a t e d by means o f t h e above The RC v a l u e s  ferent  respect  This  i n dura-  to i t s duration  i n c r e a s e a n d an RC v a l u e  ponds t o a r e l a t i v e  as  SD(k)  be r e p o r t e d  for dif-  separately.  o f s i g n i f i c a n c e mentioned i n t h i s  study  o f s i g n i f i c a n c e e s t a b l i s h e d by t - t e s t s  follows: * = significant  b e y o n d t h e 0.05% l e v e l  **  = significant  b e y o n d t h e 0.02% l e v e l  ***  = significant  b e y o n d t h e 0.01% l e v e l  **** = s i g n i f i c a n t  b e y o n d t h e 0.005%  level  -  6•3  68  -  R e l a t i v e Change o f V o w e l s It  the b a s i s  became n e c e s s a r y  i n the  of t h e i r apparently  course of a n a l y s i s ,  different  functions,  to  on  con-  s i d e r v o w e l s i n m o n o s y l l a b i c f u n c t i o n w o r d s s u c h as  prepo-  sitions,  the  pronouns,  and d e t e r m i n e r s ,  separately  from  vowels i n o t h e r w o r d s , p r i m a r i l y words b e a r i n g l e x i c a l formation.  Hereafter  in stressed  s y l l a b l e s i n words o t h e r  f u n c t i o n w o r d s , and i n a l l other 'stressed'  'stressed'  vowel w i l l  'unstressed'  syllables.  F i g u r e 6.4 d i s p l a y s the  vowel w i l l  vowels i n the other  statistical table The  III  differences  different  As c a n be s e e n , more t h a n  shows t h e  differences.  f o r vowels i n f u n c t i o n words i n the different  from the  creases'  i n t h e FAST DAF c o n d i t i o n and t o a l e s s e r  from the  'increases'  the  i n the  'increases'  SLOW DAF c o n d i t i o n .  f o r the vowels / u / , / o / ,  f u n c t i o n words were f r e q u e n t l y the  'increases'  ively.  f o r / i i / , /'6/  Most o f the  any  f o r v o w e l s i n f u n c t i o n words and  SAF c o n d i t i o n w e r e s i g n i f i c a n t l y  more,  the  between-condition  shows t h e w i t h i n - c o n d i t i o n s t a t i s t i c a l  'increases'  and  separately.  for the  'increased'  Table II  to vowels  l o n g and s h o r t  r e l a t i v e change  f u n c t i o n words  group o f v o w e l s .  refer  v o w e l s were a n a l y z e d  groups of vowels f o r each s u b j e c t .  to vowels  than the m o n o s y l l a b i c  'Unstressed'  l o n g and s h o r t  refer  in-  significantly  and  'stressed'  significant differences  SLOW c o n d i t i o n s . The r e l a t i v e c h a n g e s a n d /ae/ i n f u n c t i o n w o r d s w e r e r a r e l y  SLOW 'inextent  Furtherand / a /  different vowels  in from  respect-  occurred i n  f o r the vowels /A/ significantly  the  Stressed'  'Unstressed'  vowels  vowels  Vowels i n unction 8  3.5 3 —  i  u  A  6  m  words I  CONDITION  n  I CONDITION  ur  CONDITION ISC  u[ e I ]  2.5 -  o  2 —  l i p  1.5 I-  SUBJECT I  0.5 -  u*  A'  3.5 -  6  6[e\]  1  3 — 2.5 -  o  2 — 1.5 _K33  I —  SUBJECT  2  SUBJECT  3  0.5 -  3.5 3 O  —  I  a  2.5 2 — 1.5 I0.5  f^  m=  Figure  6.4.  U  A  O  u[al]  r it  ae  CL  u  R e l a t i v e change i n d u r a t i o p . f o r v o w e l s i n t h e SLOW SAF ( I I ) , t h e SLOW DAF ( I I I ) , and t h e FAST DAF (IV) c o n d i t i o n s w i t h r e s p e c t t o t h e NORMAL c o n d i t i o n .  -  70  -  SLOW DAF  Subject SLOW SAF  Table I I .  FAST DAF  1  NS  **  2  *  ****  3  **  ****  B e t w e e n - c o n d i t i o n d i f f e r e n c e s i n r e l a t i v e change of vowels i n o n e - s y l l a b l e f u n c t i o n words.  -  71  -  SLOW SAF /ii/  vs. /u/  Subject  /6/  /a/  function words,  ****  NS  2  ** **  ****  **  3  ***  NS  ***  in  function words,  /o/  sentence  1  NS  ***  NS  2  ****  ****  ****  3  *  NS  NS  i n function words,  / a / sentence  1  * * * "k  NS  NS  2  NS  *  NS  3  NS  NS  NS  'stressed' Subject  sentence  *  v s . /A/ and / a /  Subject  /u/  FAST DAF  1  v s . /o/  Subject  in  SLOW DAF  vowels v s .  /e/  i n function words,  all  sentences  1  ****  ****  ****  2  ****  ****  ]vjg  3  ****  ****  ftjg  Table I I I .  W i t h i n - c o n d i t i o n d i f f e r e n c e s i n r e l a t i v e change o f ' s t r e s s e d ' l o n g v o w e l s and v o w e l s i n f u n c t i o n words.  72  -  different  from t h e r e l a t i v e  The  number o f o c c u r r e n c e s o f /A/ and /  small  account  changes f o r t h e vowel  when t h e s e r e s u l t s a r e d i s c u s s e d . d i f f e r e n c e between  words was n o t s i m p l y /%/  i n words o t h e r  were compared w i t h sults,  presented  a significant words o t h e r  than  i n motor t a s k s  300 in are as  'stressed'  'stressed'  below,  t o assure  v o w e l s and /a/  i n table  that  i n function  i n vowel q u a l i t y ,  The s t a t i s t i c a l r e -  IV, i n d i c a t e t h a t i n relative  there  i s rarely  c h a n g e between / s / i n  f u n c t i o n words and ' s t r e s s e d '  vowels.  (1968) i n a d i s c u s s i o n o f r h y t h m i c  behaviour  proposed t h a t  between  t h e minimum i n t e r v a l i n speech  study  (beats)  1000 msec.  t h a t when t h e v o w e l s  e x a m i n e d , t h e s p e e c h power t r a c e  called  be o f f e r e d  In order  vowels.  msec and t h e maximum i n t e r v a l  high  vowels.  than f u n c t i o n words, e . g . , i n / s i t e d / ,  f o r rhythmic behaviour  the present  will  due t o t h e d i f f e r e n c e s  difference  Allen  acts  / (N=3) m i g h t  f o r the n o n s i g n i f i c a n t r e s u l t s f o r these  However, an a l t e r n a t i v e e x p l a n a t i o n  the  ffi  /a/.  i s probably I t was f o u n d  i n function  words  on t h e mingograms i s  f o r t h e s e v o w e l s a s f o r t h e v o w e l s w h i c h have heen 'stressed'  vowels i n t h i s  study.  When t h e d a t a a r e  e x a m i n e d i n v i e w o f A l l e n ' s minimum a n d maximum l i m i t s , i t becomes e v i d e n t ,  that  the subjects,  speech and p a r t i c u l a r l y SAF ed  a t the very  a n d SLOW DAF c o n d i t i o n s , the physical e f f o r t  a t the slower rates o f slow r a t e  i n t h e SLOW  l e n g t h e n e d v o w e l s and i n c r e a s -  w i t h w h i c h t h e y were p r o d u c e d i n  c o m p a r i s o n w i t h t h e NORMAL c o n d i t i o n v o w e l became a b e a t i n t h e r h y t h m i c  such, t h a t succession  each o f speech  -  Table IV.  -  SLOW SAF  SLOW DAF  FAST DAF  1  NS  NS  NS  2  NS  ***  NS  3  **  *  *  ' S t r e s s e d ' vowels v s . not i n f u n c t i o n words Subject  73  / / 9  Within-condition differences o f ' s t r e s s e d ' v o w e l s and / a / words.  i n r e l a t i v e change not i n f u n c t i o n  -  units.  74  -  F u r t h e r examination r e v e a l e d t h a t the  tween the n o r m a l l y s t r e s s e d msec a t  the  speech,  v o w e l s would have exceeded  slower rates of speech,  additional beats.  In other  t h e more l i k e l y  terms,  will  the  speech u n i t s .  between the in  vowel  rhythmic succession  T h i s may e x p l a i n why t h e  differences  SLOW SAF and SLOW DAF c o n d i t i o n s f o r v o w e l s s i g n i f i c a n t as t h e  differences  SLOW SAF and FAST DAF c o n d i t i o n a n d why i n  FAST DAF c o n d i t i o n t h e r e s h o u l d be f e w e r s i g n i f i c a n t ferences words.  between  'stressed'  The e x c e p t i o n s ,  which d i d not increase parison with other the  i.e.,  significantly  i n d u r a t i o n i n com-  i t was f o u n d t h a t t h e s e (two s t r e s s e d  from each o t h e r  in /at/,  cussion of t h i s  latter  the  'stressed'  analysis of  A n a l y s i s of the revealed that creased'  vowels)  by more t h a n  the  for a shorter  vowels are  'stressed'  which 1000 m s e c .  /A/ in /Ap/ in  vowel.  p o i n t f o l l o w s when t h e  i n g e n e r a l /ix/  i n the  exceptions  o c c u r r e d i n an e n v i r o n m e n t t h a t  NORMAL c o n d i t i o n w o u l d c a l l  in  the v o w e l s i n f u n c t i o n words  a d d i t i o n , these e x c e p t i o n a l vowels, e . g . ,  and /ae /  dif-  v o w e l s and v o w e l s i n f u n c t i o n  two b e a t s  were n o t s e p a r a t e d  the  v o w e l s , w e r e now e x a m i n e d i n v i e w o f  above h y p o t h e s i s :  o c c u r r e d between  In  the  rate of  a normally unstressed  f u n c t i o n w o r d s w e r e n o t as  between the  slower the  be1000  thus n e c e s s i t a t i n g  be p r o l o n g e d and f o r m a b e a t i n t h e of  intervals  A dis-  results  of  discussed.  vowels  (see  figure  was c o n s i s t e n t l y m o s t  SLOW SAF c o n d i t i o n , and more  SLOW DAF c o n d i t i o n t h a n  the  6.4)  'in-  'increased'  i n t h e FAST DAF c o n d i t i o n .  -  The  reverse  occurred than the  the greatest  increase  i n t h e FAST  DAF c o n d i t i o n ,  / u / was m o r e  'increased'  'stressed' o f /6/  consistently Table  relative  change  different /a/)  from  'increases'  i n t h e SLOW  a n d 2.  For subject  3 this  although  was  t h e same,  namely  low  vowels.  were  different /a/  with f o r /o/  creased' the  1.51  (primarily  f o r subjects  rarely  reached  of the difference  'increased'  than the  between-condition  dif-  ( n o t shown  i n table  respect  t o t h e SLOW  SAF c o n d i t i o n ,  and / i /  were  each  i n t h e FAST  different  o fthe ;  findings more  slowest  average  significantly  form)  significantly  DAF c o n d i t i o n a n d  f o r one s u b j e c t  i n the  condition.  Analysis above  vowels.  vowels  f o rone s u b j e c t  was s i g n i f i c a n t l y  SLOW DAF  the  significant  f o r 'stressed'  the, ' i n c r e a s e s '  DAF c o n d i t i o n s  the direction  The only  as f o l l o w s :  of 'stressed'  difference  environ-  differences i n  f o r / u / were  / u / was more  /u/ i n  of /u/ i n this  f o r t h e low vowels  S A F a n d SLOW  significance,  ferences  groups  with  o f / u / because o f  the within-condition  the 'increases'  condition  DAF c o n d i t i o n .  behaviour  f o rt h e four  c a n be seen,  i n any o t h e r  i n the analysis  different  V shows  vowel  i n t h e FAST  was n o t i n c l u d e d  ment.  1  f o r/ o / , where  exception  the  As  was t r u e  any o t h e r  /uel/  75 -  than  rate,  RC v a l u e s  i n t h e SLOW  vowels  i n that  i n the passage  vowels  any o t h e r  type  i n function o f vowel  i . e . , i n t h e SLOW f o r vowels  1.3 8  words  'in-  and most a t  SAF c o n d i t i o n .  i n the passage  SAF c o n d i t i o n ,  substantiated  The  amounted t o  i n t h e SLOW D A F  -  /a/  76 -  /?/  / i /  /u/  SLOW SAF Subject 1  NS NS NS  2  /a/  Subject 1  NS * NS  2  /5V  NS NS NS  Subject 1  NS **  **** NS NS * NS  2  / i /  **** ****  SLOW DAF Subject 1 /a/  2  /6/  Subject 1 2  /!/  NS NS NS  NS NS NS  **** *** ***  NS NS NS  ** *  Subject 1  NS ** NS NS  2  FAST DAF Subject 1  75/  NS NS NS  2  /a/  Subject 1  2  NS *** NS  * ** * NS NS  NS * NS  NS NS NS  Subject 1  / i /  T a b l e V.  NS NS NS  2  Within-condition differences "stressed vowels. 1  i n relative  change o f  -  condition,  and  Why and  77  1.2 0 i n t h e  was  / u / more  particularly  a n s w e r s w i l l be  vowel /u/  itself  explains  the  i n which /u/ which the the  greater  greater  /o/  and  Peterson,  (b)  and  vowels  SLOW c o n d i t i o n s ?  in detail: other  (a)  the  that  environment  environment  such, t h a t  Two  the  vowels such  (b)  place  of  d i f f e r s , as  /u/  differs  back.  explained  i t will  in  explain  articulation,  vowel d u r a t i o n ,  vowels are  followed  stops,  followed  e.g.,  articulation, and  c o n s o n a n t on  longer,  i s true  the  /a/  (Lehiste vowels  behave d i f f e r -  facts. that voicing,  i n that order, in voiced  exert  an  environments  and  followed  pre-  a b i l a b i a l place According  i n f l u e n c e of  i s minimal.  Chen  the  l a n g u a g e s as w e l l .  of to  preceding  (197 0)  before  by  and  g e n e r a l l y s h o r t e r ; when  i n vowel d u r a t i o n  for other  (1962) s u g g e s t e d t h a t  from  w h e r e a s when p r e c e d e d  (1960) , t h e  increase  these  generally shorter.  vowel d u r a t i o n  t h a t the  should  (1953) f o u n d  consonants with  vowels are Lehiste  /u/  when p r e c e d e d  vowels are by  does / i / ,  from a l l o t h e r  i n terms o f  generally longer;  by  Why  Fairbanks  fricatives,  consonant  from the  other  a lower i n t r i n s i c amplitude  House and  i n f l u e n c e on  firmed  examined  vowel /u/  1959)  e n t l y c a n n o t be  Peterson  i n the  'increase',  t h a t i t i s c l o s e and  c e d e d and  than the  d i f f e r e d " f r o m the  i n t h a t i t has  vowels are  'increased'  vowels o c c u r r e d  The  and  manner and  condition.  'increase'.  (a)  in  differs  occurred,  other  FAST DAF  more t h a n / a /  different  it  -  a  convoiced  Delattre  changes i n vowel d u r a t i o n  are  -  for  the most  cipation "would Chen an  of  one  (1970)  a voiceless shorter  other  effort"  'shorten'  proposed  vocal  tract  of  When  /u/  vowel"  observed  (vowel)  duration  to  explain  a vowel  most  duration  i n an  of  faster  environment  that  close  position  according  to  the  in a  above  vowel  occurring  least  frequently  i n such  was  /a/.  Does  imply  that,  the  decreased,  vowels  i n an  environment,  longer  vowel  duration,  vowels  i n an  environment  the  vowel?  rates  of  shorter  of  the  that est  t o be  fact  f o r /$/  earlier  jaw at  other  'stressed'  'increase' of  tend  shorter  an  environment  of  shortens the  do  longer  relatively  speech  results  prolonged r e l a t i v e l y  which  more  findings.  rate  which  the  more  in a  more  than  duration  segments  at  is  of  slower  prolonged  than  segments? The  alysis  are  In o t h e r terms,  speech  when  for  the  with  appeared  results  from  stop.  compared /u/  voicing)  1142).  satisfactorily  i s now  which  no  transitions  The  this  p.  before a voiceless  sentence  the vowel  i.e., "anti-  closures,  (ibid.,  a more  sentences, i t i s evident  frequently  conditioned,  (clusters,  the  that  consonant  the  -  physiologically  greater  make  open  part  78  100-msec  that  i n the  lays  were  interest  vowels i n the  reported  activity  of  delay,  no  the  an-  the  consistently  FAST  DAF  condition.  In  Sussman  Smith  vowels  by  / i / ,  i t i s perhaps  p r e s e n t s t u d y , where  used,  from  was  findings  f o r the  emerging  consistent  /e/ not  longer  and too  than  'increases'  and  greater view  /ae/ was  (1971) long-  surprising 100-msec  under  DAF  de-  f o r the  -  79  -  v o w e l s / £ / , / u / and / a / w e r e f o u n d . consistent sible,  f o r /6/  'increases'  that  to produce  How, t h e n ,  be e x p l a i n e d ?  can  the  it  pos-  Is  f o r /6 /  a l o n g e r t h a n 100-msec d e l a y i s  longest  jaw a c t i v i t y ?  would attempt  Any h y p o t h e s i s  which  to e x p l a i n s e l e c t i v e vowel d u r a t i o n  under  DAF w o u l d h a v e t o a c c o u n t h a v e t o move f r o m t h e time d e l a y s .  needed  f o r the d i s t a n c e  rest  the  p o s i t i o n as w e l l  In the present  articulators  as  for  critical  study, vowel context,  which  t u r n e d o u t t o be a p o s s i b l e s o u r c e o f v a r i a t i o n o f ' i n creases'  f o r v o w e l s , was n o t c o n t r o l l e d w e l l  t h a t no s u c h h y p o t h e s i s c a n be  enough,  so  offered.  4  6.3  R e l a t i v e Change o f In g e n e r a l ,  in  consonants  t h e SLOW SAF c o n d i t i o n ,  crease'. the  The e f f e c t  and  t e n d e d t o be  'decreased'  w h e r e a s v o w e l s showed an ' i n -  was s t a t i s t i c a l l y s i g n i f i c a n t b e y o n d  0.01% l e v e l w i t h one e x c e p t i o n f o r t h e  C o n s o n a n t s t e n d e d t o be  'decreased'  three  a l s o i n the  subjects. SLOW DAF  FAST DAF c o n d i t i o n s b u t n o t as c o n s i s t e n t l y o r  significantly true  as i n t h e  SLOW SAF c o n d i t i o n .  f o r the analyzed main experiment It  for  Consonants  h a s b e e n s u g g e s t e d when t h e  T h i s was  a l s o appears rates  to r e s u l t  greater  for that  l o n g e r segments  segment. at  i n a l o n g e r segment  i n greater  also  passage. ^increases  / d / i n t h e SLOW c o n d i t i o n s w e r e d i s c u s s e d ,  environment which r e s u l t s  as  'increases'  that  an  duration, at  The q u e s t i o n was a s k e d  slower whether  slower r a t e s of speech tend to  be  -  80 -  r e l a t i v e l y more p r o l o n g e d t h a n s h o r t e r is  i n fact  the  consonants, creased'  case  'increased'  A discussion follows  consonant a n a l y s i s are  the  and  'final'  f i r s t or l a s t  for  RC f o r  'initial'  'initial'  'initial' / m / and  i n the  c l o s u r e and  more u n d e r t h e the  'increased' less or  fers  'decreased'  It w i l l  in this  only,  emerged f o r t h e  be remembered t h a t  study to the  whereas  'final'  'initial'  d i t i o n s , the  and  seen,  less  sentences,  'initial' o f an  stop i n c l u d e s the A n a l y s i s of the  in  consistently 'increased'  As c a n be  'final'  closure part  than  seen,  voiceless closure  re-  'initial'  release  of  stop  the  passage r e v e a l e d  / b / was a l s o i n c r e a s e d u n d e r t h e DAF c o n -  increase  significantly the  stops,  'increased'  i n t h e DAF c o n d i t i o n s .  c l o s u r e and a s p i r a t i o n . that  nasals  mean the  As c a n be  'decreased'  'Final'  to  shows  i n t h e SLOW SAF c o n d i t i o n and e i t h e r  no c o n s i s t e n t p a t t e r n stops.  'final'  /m/ either  DAF c o n d i t i o n s o r  SLOW SAF c o n d i t i o n . ,  the  statements below,  F i g u r e 6.5  nasals.  'initial'  of  s y l l a b l e but w i l l  c l o s u r e and  'final'  con-  not n e c e s s a r i l y j u s t  pre- or p o s t v o c a l i c r e s p e c t i v e l y . average  'de-  must be  the r e s u l t s  In the  refer  consonant  that  s h o u l d be  factors  after  reported. will  this  i n comparison with vowels.  U n d e r DAF a number o f o t h e r  'initial'  If  t h e n i t w o u l d seem r e a s o n a b l e  i n p a r t i c u l a r noncontinuants,  or less  sidered.  segments.  i n t h e DAF c o n d i t i o n s b e i n g  different  from the  SLOW SAF c o n d i t i o n .  w h e r e no s u c h o b s e r v a t i o n was made,  occurred only after  highly  a consonant p r e v o c a l i c a l l y ,  In  /b/  whereas  in  -  81 -  SUBJECT  I • i  SLOW SAF  |  | SLOW DAF FAST DAF  SUBJECT  1  SUBJECT  2  3  SUBJECT (PASSAGE)  •Initial' voiceless closure Figure 6.5.  'Final' voiceless stops  'Initial' /m/  'Final' Nasals  R e l a t i v e change i n ' i n i t i a l ' v o i c e l e s s c l o s u r e , 'final' v o i c e l e s s s t o p s , ' i n i t i a l ' / m / and ' f i n a l ' nasals.  -  the  passage /b/ occurred  shows t h e r e l a t i v e the  82 -  word-initially.  Figure  change f o r a s p i r a t i o n a s s o c i a t e d  release of 'initial'  aspiration  only  voiceless stops.  'decreased'  for a l l subjects  6.6  with  As c a n be s e e n , i n a l l conditions.  However, when b e t w e e n - c o n d i t i o n d i f f e r e n c e s i n r e l a t i v e change f o r a s p i r a t i o n a r e e x a m i n e d , i t c a n be s e e n i n F i g ure  6.6 t h a t s u b j e c t s  crease' ject  1 a n d 2 showed a n e v e n  i n a s p i r a t i o n i n t h e DAF c o n d i t i o n s , w h e r e a s  3 showed a l e s s e r  statistical 3 differed  f u r t h e r from s u b j e c t s  Table  sub-  V I shows t h e  observations.  Subject  1 and 2 i n t h a t  frica-  'increased'  or less  'decreased in 1  DAF c o n d i t i o n s t h a n i n t h e SLOW SAF c o n d i t i o n ;  (significant and  'decrease*.  s i g n i f i c a n c e o f these  t i v e s were e i t h e r more the  f u r t h e r 'de-  a t t h e .05% l e v e l i n t h e SLOW DAF c o n d i t i o n  a t t h e .005% l e v e l  differences,  although  1 and 2, d i d n o t r e a c h Haggard  i n t h e FAST DAJT c o n d i t i o n ) . i n t h e same d i r e c t i o n  for  s i g n i f i c a n c e f o r these  (1971) , a s q u o t e d  The  subjects  subjects.  i n MacNeilage  (1972) ,  found t h a t o f t h e p o s t v o c a l i c consonants, t h e a b s o l u t e l y final  c o n s o n a n t s a p p e a r t o have t h e l o n g e s t  In t h e p r e s e n t f r e q u e n t l y more tions this for  consonants  'increased'  'final'  i n that nasals  position.  impression  that  i n this  'Final'  for a l l subjects were o b t a i n e d  This  p o s i t i o n were  than consonants  i n t h e SLOW SAF c o n d i t i o n . point,  final  study,  durations.  i n other  nasals  the highest  illustrate RC v a l u e s  consistently i n absolutely  appears t o f u r t h e r confirm t h e  a t a slower  posi-  r a t e , the normally  longer  -  83  -  • H I  SLOW S A F I SLOW DAF  S 5 3 FAST DAF  0 —  Figure  SUBJECT  6.6.  I  SUBJECT  2  SUBJECT  3  R e l a t i v e change i n a s p i r a t i o n i n the SLOW S A F , SLOW DAF and FAST DAF c o n d i t i o n s w i t h r e s p e c t t o t h e NORMAL CONDITION.  -  84  -  SLOW DAF  FAST DAF  SLOW SAF Subject  Table V I .  1  NS  2  ****  3  NS  B e t w e e n - c o n d i t i o n d i f f e r e n c e s i n r e l a t i v e change of a s p i r a t i o n a f t e r ' . i n i t i a l ' v o i c e l e s s c l o s u r e .  -  85 -  segments a r e ' i n c r e a s e d '  more t h a n n o r m a l l y  ments, o r ' d e c r e a s e d ' l e s s . t h e n i t w o u l d be e x p e c t e d dition  sure.  the  particularly  SLOW SAF c o n d i t i o n t h a n d e n t a l  since  next a r t i c u l a t i o n .  RC v a l u e  than d e n t a l  or velar  closures  clo-  i s needed i n systematic  change f o r t h e d i f f e r e n t  I t appears then, t h a t , while  closures  i t i s true  i n t h e SLOW SAF c o n d i t i o n v o w e l s a r e m o r e ' i n c r e a s e d '  vowel i s l o n g e r ,  more  'increased'  c o n s o n a n t s more vocalic  'increased'  Instead,  'increased'  dimension  that  beyond  a l l normally  SLOW SAF c o n d i t i o n .  a simple  'increases' In order  postlonger  v o i c i n g , and p l a c e and stop  f o r consonants, a l l appear t o p l a y  i n determining  i n other  final  u n d e r t h e SLOW SAF c o n d i t i o n .  p o s i t i o n i n the s y l l a b l e ,  manner o f a r t i c u l a t i o n ,  and a b s o l u t e l y  than consonants  positions, i t i s not true  segments a r e more  i n which the  t h a n v o w e l s i n an e n v i r -  onment, i n w h i c h t h e v o w e l i s s h o r t e r ,  of  under  out, b i l a b i a l  t h a n c o n s o n a n t s and v o w e l s i n a n e n v i r o n m e n t ,  roles  clo-  one m i g h t e x -  However, t h e e x p e c t e d  i n relative  were n o t f o u n d . that  longer  This  o r v e l a r c l o s u r e s be-  t h e tongue i n t h e l a t t e r  differences  closures  (1972) h a s p o i n t e d  c l o s u r e c a n be m a i n t a i n e d  the  i s true,  not f o r voiced  c l o s u r e t o show a h i g h e r  c a u s e , as M a c N e i l a g e  seg-  t h a t u n d e r t h e SLOW SAF c o n -  Furthermore, o f the d i f f e r e n t the b i l a b i a l  sure  impression  c l o s u r e w o u l d e x h i b i t t h e l o w e s t RC v a l u e .  was n o t a l w a y s t h e c a s e ,  pect  If this  shorter  /  continuant  differential  f o r consonants  i n the  to specify the role  o f each  t h e p a r a m e t e r s , e n v i r o n m e n t w o u l d have t o be s t r i c t l y  -  86 -  controlled. The  f i n d i n g s o f the consonant a n a l y s i s a r e best  discussed, marize, sure  however, i n t e r m s o f r e a c t i o n t o DAF.  'initial'  (not i n a c l u s t e r ) , ' i n i t i a l '  a greater  'increase'  conditions revealed the  voiceless closure,  or a lesser  that b i l a b i a l  closure  DAF  closure  instead  effect. that  f o r closures  initial  i n that  RC v a l u e  under  out here,  i n terms o f c o n s i s t e n t l y  u n d e r t h e SLOW SAF c o n d i t i o n ,  be remembered t h a t  voiceless closure  Huggins  'increases'  u n d e r DAF. loop  cludes  assume t h a t  that  one c a n n o t  important  found delay.  parameter i n  MacNeilage  (1972) i n  c o n t r o l system i n speech auditory  r o l e i n the c o n t r o l of running  somatic sensory  (1968)  grew l i n e a r l y w i t h  a discussion of closed  initiation  bilabial  change f o r ' i n -  p o s i t i o n a p p e a r s t o be a c r u c i a l  determining  an  analysis  t h e d i f f e r e n c e s must be a t t r i b u t e d t o t h e DAF  Itwill  'Initial'  i n relative  showed  t h e most t o  I t must be p o i n t e d  c a n n o t be e x p l a i n e d  l o w e r RC v a l u e s but  Further  contributed  clo-  i n t h e DAF  e x h i b i t e d most c o n s i s t e n t l y a h i g h e r  that the observed d i f f e r e n c e s itial'  'decrease'  involving closure,  t h a n u n d e r SLOW SAF.  voiced  /m/ a n d f r i c a t i v e s  t h a n i n t h e SLOW SAF c o n d i t i o n .  observed d i f f e r e n c e s  closure  'initial'  To sum-  control i s considered  feedback  conplays  speech, b u t  necessary  f o r the  o f speech.  "The command n e c e s s a r y f o r a n a r t i c u l a t o r to reach a f i x e d s p e e c h - i n i t i a l p o s i t i o n must be c o n d i t i o n a l upon t h e p r e - s p e e c h p o s i t i o n o f t h a t a r t i c u l a t o r w h i c h no d o u b t v a r i e s from o c c a s i o n to occasion." (ibid.,pp.44-45).  -  It  i s entirely  the  only  type  speech.  p o s s i b l e , t h a t i n the normal case t h i s i s o f feedback needed  position  auditory  sensory  I f we  respect  to articulator  and a t t h e same t i m e r e c e i v e s a i r - c o n d u c t e d  conducted  feedback)  information,  furthermore  open l o o p  system takes  relatively  the system t h a t i t (the a i r i s at variance  This  f o r vowels.  with  t h e som-  t h e n h e s i t a t i o n m i g h t be e x p e c t e d .  over,  than i t i s p o s s i b l e t h a t  of a speech u n i t should  more t h a n w o u l d be e x p e c t e d  speech.  be  f o r a slower  does n o t e x p l a i n t h e g r e a t e r  However, s i n c e v o w e l s were more  6.3  under  rate  'increases' 'increased' phenomen-  c a n n o t be a t t r i b u t e d t o DAF b u t must be c o n s i d e r e d  cal  an  prolonged  a l s o a t t h e s l o w e r r a t e o f s p e e c h u n d e r SAF, t h i s on  audi-^-  assume t h a t o n c e s p e e c h i s i n i t i a t e d  DAF t h e b e g i n n i n g  of  feedback with  feedback which informs  atic  f o r the i n i t i a t i o n of  I f t h e s y s t e m u n d e r DAF, however, r e c e i v e s t h e  normal somatic sensory  tory  87 -  typi-  o f a slower r a t e of speech i n g e n e r a l . 5  . . Repetitions Figure  6.7  ferent durations and that  shows t h e number o f r e p e t i t i o n s o f d i f -  f o r each s u b j e c t  the cumulative  % repetitions.  length of the repeated  5, c o r r e l a t e d w i t h  were p r o d u c e d . frequently  3.  The g r a p h s  revealed  s e g m e n t s , as d e f i n e d  the length of delay  As c a n be s e e n , s u b j e c t  than s u b j e c t  than s u b j e c t  i n t h e FAST DAF c o n d i t i o n  2 and s u b j e c t  i n chapter  under which  they  1 repeated  more  2 more  frequently  I t m i g h t be m e n t i o n e d h e r e t h a t  the l a t t e r  2  7 -  o b i—  6 -  rr  4 -  cr u  2 -  SI  Q. ° CD  ODURATION  I O  25  I  I  I  I 7 5 I 125 I 175 I 2 2 5 I 2 7 5 I 3 2 5 I 3 7 5 I 4 2 5 50 100 150 200 250 300 350 400  I I  0  I  25  I I  50  I  75  I I  100  I  125  I I  I  I  I  | I  I  I  175 ' 2 2 5 I 2 7 5 ' 3 2 5 150 200 2 50 300  I I  0  I  25  I I  50  1  75  I  1  I  100  125  I  I  1  I  I  1  1  I  175 I. 2 2 5 ' 2 7 5 I 150 200 250 3 0 0  100 —  2  9 0 -  o P  8 0 -  tu  70-  UJ DC  6 0 -  CL  oo 00  4 0 C < 3  O  3 0 20-  100 —  DURATION  I  0  25 50  I  75 100  I  I  125 150 200  SUBJECT  175 250  I  I  Delay used i n the experiment: 2 4 0  Figure  6.7.  I  I  225 275 300 350 4 00  Number o f r e p e t i t i o n s  5 5 I 125 I 175 I 2 2 5 I 2 7 5 I 3 2 5 3 2 5 II 32755 II 47 2 0 50 100 150 200 250 300 SUBJECT  I I  0  I  25  I I  50  I  75  I I  I  175  SUBJECT  3  100  150  I I' I I I I 2 2 5 I 275 I  200  250  230  200  and c u m u l a t i v e % r e p e t i t i o n s  I  I I  125  i n t h e FAST DAF c o n d i t i o n .  300  -  89  f i n d i n g was  also true  sequence of  articulation.  most a d d i t i o n s  -  f o r other  unrelated  additions  Subject to the  to the  1 exhibited  text  and  expected  by  rather  far  the  bizarre  h. i n n a t u r e , e.g., In the  /kam  SLOW DAF  occurred  fa&e* / became /k  condition only  number.  In v i e w o f  the  rarity  have b e e n o b s e r v e d  by  experimenters,  subjects  five  2 and  for English  i t m i g h t be  r e p e t i t i o n s are  not  K o z h e v n i k o v and  repe-  noted here, that  instance).  in  speakers under  DAF  although  double r e p e t i t i o n s ,  produced m u l t i p l e  r e p e t i t i o n s i n one  i n the  (1968) f i n d i n g  w i t h which m u l t i p l e  3 primarily exhibited  1 frequently  multiple ers  isolated repetitions  at a slower r a t e r e p e t i t i o n s decrease  titions  subject  a few  w h i c h i s i n a g r e e m e n t w i t h MacKay's  t h a t u n d e r DAF  past  ambagl f ep a f aoa"/•  -  repetitions  This  peculiar to  Chistovich  (up  does s u g g e s t the  to that  Russian  speak-  (1965) s t u d y .  Fur-  t h e r m o r e , t h e s e r e p e t i t i o n s were always, r e p e t i t i o n s o f syllables,  which i s i n agreement w i t h the  above a u t h o r s . was  repeated  a glottal after  Finally,  a t the  stop  was  i t was  beginning  i n s e r t e d , and  a c o n s o n a n t , e.g.,  Laryngealization initial  distorted arrival  by  DAF  phases a t the  was  vowel  /i?ist/, repeated  inserted.  preceded a vowel i n  syllable-  conditions.  (1959) f o u n d t h a t  altering  e.g.,  when a v o w e l was /h/  the  t h a t when a  a syllable,  /kaham/, an  frequently  p o s i t i o n i n the Stromsta  of  observed  findings of  open  side-tone,  which  was  i t s f r e q u e n c y components o r i t s two  phonation while phonating  ears,  produced a blockage  a vowel i n f a l s e t t o .  Van  in Riper  -  (1971),  90 -  who, l i k e many o t h e r s  (for a review  s e e Timmons and  B o u d r e a u , 1 9 7 2 ) , c o n s i d e r n a t u r a l and a r t i f i c i a l to  be s i m i l a r  in  t i m i n g o f a n t a g o n i s t i c muscle groups a t the l a r y n g e a l  level  behaviours,  hypothesized  that  stutter  are r e s p o n s i b l e f o r the observed  of  such  of  their  stutter.  a t h e o r y , Freeman and U s h i j i m a experiments,  asynchronies  In support  (1974) on t h e b a s i s  state:  " f l u e n t u t t e r a n c e i s c h a r a c t e r i z e d by p r e c i s e b a l a n c e and t i m i n g o f l a r y n g e a l a b d u c t o r and a d d u c t o r f o r c e s . In fluent utterance a b d u c t o r and a d d u c t o r f o r c e s a c t r e c i p r o c a l l y , whereas, i n s t u t t e r e d u t t e r a n c e , t h i s r e c i procity i s disrupted. I n many s t u t t e r e d utterances the l a t e r a l c r i c o a r y t e n o i d - g e n e r a l l y presumed t o be an a d d u c t o r , w i t h t h e s p e c i f i c f u n c t i o n of medial compressionachieved abnormally high l e v e l s o f a c t i v i t y . " ( i b i d . , p. S80). The  laryngealization  u n d e r DAF i n t h i s tion to  u n d e r DAF a f t e r  i n this  'initial'  than  voiceless  stutter.  'decrease'  i n aspira-  showed a l e s s e r  I t i s of particular  s u b j e c t s most of aspiration  offered  glottal  at this  stops  the expected  time  and / h / .  'decrease'.  affected u n d e r DAF least  No e x p l a n a t i o n c a n  f o r the d i f f e r e n t i a l Nor c a n t h e b i z a r r e  sequence o f a r t i c u l a t i o n  tend  are not unlike  i n t h e SLOW SAF c o n d i t i o n , w h e r e a s t h e s u b j e c t  affected  observed  c l o s u r e would  o f DAF on s p e e c h  respect t h a t those  DAF showed a g r e a t e r  stops  and a l s o t h e ' d e c r e a s e '  of natural or a r t i f i c i a l  interest  be  study  confirm t h a t the e f f e c t s  those  by  and i n s e r t i o n o f g l o t t a l  insertion of insertions  into  be r e a s o n a b l y e x p l a i n -  ed.  The c o r r e l a t i o n  of the durations of repeated  with  t h e d e l a y u n d e r w h i c h t h e y were p r o d u c e d ,  segments  is in  -  91  -  agreement w i t h t h e f i n d i n g s r e p o r t e d I n summary, the  the i n v e s t i g a t i o n  e x p e c t e d sequence  of a r t i c u l a t i o n  mistiming at the l a r y n g e a l speech ships the  disturbances are a c r u c i a l  durations  observed  into  suggests that  (a)  f o r some o f t h e  u n d e r D A F , (b) t i m e  relation-  a s p e c t o f b e h a v i o u r u n d e r DAF i n t h a t  of r e p e t i t i o n s  are r e l a t e d (c)  to the delay  multiple  a b e h a v i o u r w h i c h must  be e x p l a i n e d  (1968).  of i n s e r t i o n s  l e v e l accounts  w h i c h t h e y were p r o d u c e d and constitutes  by H u g g i n s  repetitions  i n the l a s t  i n terms o f i n d i v i d u a l  under  analysis  differences.  "A major c h a l l e n g e t h a t i s emerging f o r r e s e a r c h e r s i n s p e e c h p h y s i o l o g y , when they use s e v e r a l s u b j e c t s i n t h e i r e x p e r iments, i s t o develop speech p r o d u c t i o n t h e o r i e s which take these i n d i v i d u a l d i f f e r e n c e s i n t o account r a t h e r than i g n o r i n g them." (MacNeilage, 1972,pp. 22-23). 6.4  Summary and C o n c l u s i o n s This  normal r a t e and s p e e c h It  s t u d y has examined  a n d compared  and a t a s l o w r a t e u n d e r s y n c h r o n o u s  feedback fast  was f o u n d t h a t  differ-  considerable  s h i p between  prolongation  prolongation,  the fewer  s u b j e c t s who p r o l o n g e d more i t was n o t t r u e  that  relation-  i . e . , t h e more  the r e p e t i t i o n s ,  also  rate.  disturbance  A reciprocal  and r e p e t i t i o n ,  o n l y when r a t e was v a r i e d u n d e r D A F .  terms,  individual  i n terms o f t h e degree o f speech  produced i n the s u b j e c t s under DAF.  other  at a  u n d e r DAF a t b o t h a s l o w and m a x i m a l l y  ences e x i s t  overall  speech  existed  A t a maximum r a t e ,  repeated  frequently.  the subject  In  who r e p e a t e d  -  most f r e q u e n t l y , longation.  92 -  showed t h e l e a s t amount o f o v e r a l l  Repetitions  p e a r e d t o be r e l a t e d  pro-  a t t h e maximum r a t e u n d e r DAF a p -  t o t h e d e l a y u n d e r w h i c h t h e y were  produced. W h i l e t h e h y p o t h e s i s t h a t u n d e r SLOW SAF v o w e l s are  p r o l o n g e d more t h a n c o n s o n a n t s was s u b s t a n t i a t e d , i t  could of  n o t be c o n f i r m e d t h a t u n d e r SLOW SAF w i t h i n  the class  v o w e l s , c l o s e v o w e l s a r e p r o l o n g e d more t h a n open vow-  els.  The h y p o t h e s i s t h a t u n d e r SLOW SAF c o n t i n u a n t  con-  s o n a n t s a r e p r o l o n g e d more t h a n o b s t r u e n t s was a l s o n o t substantiated. The h y p o t h e s i s t h a t u n d e r DAF v o w e l s a n d f r i c a t i v e s are  p r o l o n g e d t h e most and t h a t p o s i t i o n w i t h i n  affects  the duration  increases  the syllable  o f each sound c l a s s  select-  i v e l y was c o n f i r m e d . The h y p o t h e s i s differ DAF  that  s p e e c h u n d e r SLOW SAF w o u l d  f r o m s p e e c h u n d e r DAF was s u b s t a n t i a t e d  open b a c k v o w e l s , f r i c a t i v e s ,  sure and a l l i n i t i a l prolonged  bilabial  initial  voiceless  under  clo-  c l o s u r e was r e l a t i v e l y  t h e n u n d e r SLOW SAF w h e r e a s u n d e r  sonants i n f i n a l  i n that  more  SLOW SAF c o n -  p o s i t i o n were r e l a t i v e l y more p r o l o n g e d  t h a n u n d e r DAF. It  had a l s o been h y p o t h e s i z e d  determine r e l a t i v e  that  stress  amount o f p r o l o n g a t i o n u n d e r  would  SLOW SAF.  It  was f o u n d t h a t u n d e r SLOW SAF a n d u n d e r SLOW DAF a n d  to  a lesser  e x t e n t u n d e r FAST DAF e a c h s y l l a b l e  beat i n the rhythmic s u c c e s s i o n o f speech u n i t s ,  formed a i.e.,  there  - 93  are  no  unstressed  The  beat manifests  segments a t v e r y itself  of the vowel i n the comparison with unstressed  stressed  slow r a t e s of  in relative  s y l l a b l e and  increased  in  r e l a t i v e l y more i n d u r a t i o n  s p e e c h power i n Thus,  normally  than  r a t e u n d e r SAF  i s not  due  normally  must t a k e p l a c e  (Chapter 2 ) , i t can  at a r e f l e x l e v e l ,  r a t h e r t h a t such a  at a c e n t r a l l e v e l ,  voluntary  s u c h as  m o t o r c o n t r o l programme l e v e l p r o p o s e d by A l l e n When t h e  r a t e i s s l o w e d u n d e r DAF  e f f e c t , slowing  Thus, s i m i l a r i t i e s expected.  can  be  i n the  takes place.  t h e DAF  effect.  One  Any  complying with  m i g h t assume t h a t t h e  to d i f f e r e n c e s i n the I f one  must be  level  and  termined at a c e n t r a l l e v e l ,  than the  while  voluntary  differences are  observed  in  attributtakes  r a t e changes are  de-  differences  DAF-slowed  a t t r i b u t a b l e to i n t e r f e r e n c e at the  o b s e r v e d s i m i l a r i t i e s m i g h t be  be  a t t r i b u t e d to  at which slowing  b e t w e e n v o l u n t a r i l y s l o w e d s p e e c h and m i g h t be  no  u n d e r DAF  assumes t h a t v o l u n t a r y  the  as w e l l .  r e s u l t i n g behaviour might  slowing  the  (1973).  s a i d t o be v o l u n t a r y  s p e e c h b e h a v i o u r u n d e r SLOW SAF  place.  by  A t a m a x i m a l l y f a s t r a t e u n d e r DAF  slowing  be  at a v o l u n t a r i l y slowed  to slowing  i . e . , a p e r i p h e r a l l e v e l , but  able  slow  segments.  r e a s o n a b l y assumed t h a t s l o w i n g  DAF  duration  f u n c t i o n words, at a very  In view of the d i s c u s s i o n  slowing  speech.  increases  speech a t a normal r a t e .  s e g m e n t s , e.g.,  rate increase  -  speech  reflex level,  a t t r i b u t a b l e e i t h e r to  i n t e r f e r e n c e at a c e n t r a l l e v e l , or a l s o to r e f l e x l e v e l  -  interference,  i f reflex  these respects tral  94  -  level  (from t h e p o i n t  interference.  reflex  level  speech  behaviour,  I n any  i s involved  observed that  The  prevocalic  the s y l l a b l e  u n d e r DAF;  and  i n view  rather  tive  caused  that  i t i s able to  of the next  study attempted  the r e f l e x  disturbances.  Chistovich, level  1965)  i s involved  slowing indicate  i n speech p r o d u c t i o n procede  being  speech  to specify  i t c o u l d n o t answer how  and  the  involvement  interference  beyond a c o n f i r m a t i o n o f p a s t  (Kozhevnikov  deny t h a t  seems t o  those changes which a r e observed  n o t u n d e r SAF,  cen-  laryngealization  c h a n g e s i n segment d u r a t i o n s u n d e r DAF  to o u t l i n e  to  than p o s t v o c a l i c  is initiated,  a b l e again a t the i n i t i a t i o n this  of the  unit  in  changes i n the  n o t u n d e r SLOW SAF  towards i t s c o n c l u s i o n , the next  Although  cannot  frequent  i s a monitored  once speech  one  i s similar  of r e s u l t s )  i n DAF-induced  especially  u n d e r DAF  of view  event,  o f t h e l a r y n x as e v i d e n c e d by u n d e r DAF.  interference  and  notice-  unit. the  rela-  attempted  u n d e r DAF  but  t h e s e c h a n g e s were  experimenters'  c o n c l u s i o n s , namely i n the DAF-induced  speech  Bibliography ALLEN, G.D. 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LENNEBERG, E . H . ( 1 9 6 7 ) . B i o l o g i c a l Foundations of ( J o h n W i l e y & S o n s , New Y o r k ) .  Language  MacNEILAGE, P . F . ( 1 9 7 2 ) . "Speech P h y s i o l o g y , " i n Speech and C o r t i c a l F u n c t i o n i n g J . G i l b e r t , E d . ( A c a d e m i c P r e s s , New Y o r k ) . MacKAY, D . G . ( 1 9 6 8 ) . "Metamorphosis of a C r i t i c a l I n t e r v a l : A g e - L i n k e d Changes i n t h e D e l a y o f A u d i t o r y F e e d back t h a t produces Maximal D i s r u p t i o n i n Speech," J . A c o u s t . S o c . Amer. 4J3, 8 1 1 - 8 2 1 . MAHAFFEY, R . B . , and STROMSTA, C P . ( 1 9 6 5 ) . "The E f f e c t s o f A u d i t o r y F e e d b a c k as a F u n c t i o n o f F r e q u e n c y , I n t e n s i t y , T i m e , and S e x , " De T h e r a p i a V o c i s e t L o q u e l a e IJE, 2 3 3 - 2 3 5 .  -  97  -  PETERSON,  G., a n d L E H I S T E , I . ( 1 9 6 0 ) . "Duration of S y l l a b l e N u c l e i i n E n g l i s h , " J . A c o u s t . S o c . Amer. 32, 693-703.  PETERSON,  G.E., a n d M c K I N N E Y , N.P. (1961). o f S p e e c h P o w e r , " P h o n e t i c a ]_, 6 5 .  RAWNSLEY,  A . I . , and HARRIS, A n a l y s i s of Normal S i d e - T o n e by Means R e s . L a b . R e p . No. S u r g e r y , Navy Dept. No. 9.  "The  Measurement  J.D. (1954). "Comparative Speech and Speech w i t h D e l a y e d o f Sound S p e c t r o g r a m s , " Med. 248, B u r e a u o f M e d i c i n e and P r o j . NM 003 0 4 1 . 5 6 . 0 3 , 1 3 ,  ROBINSON, G.M. (1972). "The D e l a y e d A u d i t o r y F e e d b a c k E f f e c t i s a F u n c t i o n o f Speech Rate," J . Exp. P s y c h o l . 95, 1-5. SALTER,  SMITH,  D. (1973). " C a p a c i t y and P s y c h o l . 6_4, 1 9 3 - 1 9 8 . K.U. (1962). Delayed (W.B. S a u n d e r s Co.,  Delayed  Speech,"  Br.  J.  S e n s o r y Feedback and B e h a v i o u r P h i l a d e l p h i a & London).  STROMSTA, C P . (1959.) "Experimental Blockage of by D i s t o r t e d S i d e t o n , " J . Speech H e a r i n g 2, 2 8 6 - 3 0 1  Phonation Res.  SUSSMAN,  H.M., under Amer.  TIMMONS,  B.A. (1971). "Sex as a F a c t o r I n f l u e n c i n g Sensitiv i t y t o Delayed A u d i t o r y Feedback," P e r c e p t u a l and M o t o r S k i l l s 3 2 , 82*4-826.  TIMMONS,  B . A . , . a n d BOUDREAU,J.P. ( 1 9 7 2 ) . "Auditory Feedback as a M a j o r F a c t o r i n S t u t t e r i n g , " J . Speech H e a r i n g D i s . 3_7, 4 7 6 - 4 8 4 .  VAN  a n d S M I T H , K.U. (1970). "Jaw M o v e m e n t s Delayed A u d i t o r y Feedback," J . A c o u s t . Soc. 5fJ, 6 8 5 - 6 9 1 .  R I P E R , C. (-1971) . The N a t u r e o f S t u t t e r i n g H a l l , Inc., Englewood C l i f f s , N.J.).  YATES, A . J .  (1965). "Delayed i n g , " Q u a r t . J . Exp.  ZELNIKER,  (Prentice-  A u d i t o r y F e e d b a c k and P s y c h o l . 1_7, 1 2 5 - 1 3 1 .  Shadow-  T. ( 1 9 7 1 ) . " P e r c e p t u a l A t t e n u a t i o n o f an I r r e l e v a n t A u d i t o r y V e r b a l I n p u t as M e a s u r e d by an I n v o l u n t a r y V e r b a l Response i n a S e l e c t i v e - A t t e n t i o n T a s k , " . J . E x p . P s y c h o l . 87, 5 2 - 5 6 .  -  98 -  Experimenter  Number of Subjects  Delay in msec.  Level or Gain of feedback signal  Error and Duration Measures  Lee (1950b)  5  0,40,140,280  unspecified (high enough to produce substantial disturbance  Total duration  Black (1951)  22  0 to 300 i n 30 msec. increments  85-90 dB at earphones  Mean of total duration  Fairbanks (1955)  16  0,100,200, 400,800  30 dB above an arbitrary reference  Fairbanks and" Guttman (1958)  (based on Fairbanks (1955) experiments)  Chase (1958)  20  0,216  20 dB above the vocal output  Kozhevnikov and Chistovich (1965)  5  0,100,210, 300,470  115 dB at earphones  a) total instances of error, b) total duration c) rate of instance of error, d) correct word rate, e) total word rate f) error word rate  a) classification of errors according to type, b) number of phonemes per error Number of times [b] was repeated i n 5 sec. a) phonemes per sec., b) duration of repeated syllables and of segments within syllables, c) number of repetitions i n any one instance of repetition.  Number of Subjects  Experimenter  Level or Gain of feedback signal 45 dB above vocal output 45 dB above vocal output  a) Number of repetitions per syllable b) Total duration Number of correct syllables  35 dB above vocal output (70-75 dB speaking level)  a) t o t a l duration b) number of repetitions c) acoustic segment durations  MacKay 1968 a)  13  200,263  b)  13  0,100,150,200, 263,375,524,750  Huggins (1968)  1  0,80-400 i n 10 msec increments  Fletcher and Yates (1971)  Error and Duration Measures  Delay i n msec.  200 50 i n experiments I, II and I I I , 48 i n experiment IV.  35 dB above vocal output  Sussman and Smith (1971)  4  0,100,200,300, 400  unspecified (high enough to mask boneconducted feedback)  Robinson (1972)  4  0,200,225,250, 275,300  unspecified (feedback signal was accompanied by "pink" noise masker)  Number of times a part i c u l a r sound was repeated i n 5 seconds  Extent of a) jaw opening b) jaw velocity during opening and closing c) duration of jaw activity Number of errors  Appendix Pilot  B  Study  Passage  [Once upon a t i m e ] , a number o f mice c a l l e d a meeting, to decide upon the b e s t means of r i d d i n g of  a c a t t h a t had k i l l e d so many o f them.  themselves Various  plans were t a l k e d about, but none o f them chosen.  A  young mouse came forward, and s a i d t h a t a b e l l should be hung round the t y r a n t ' s neck. hear the c a t coming, suggestion was  Then they would a l l  and so be a b l e t o escape.  r e c e i v e d w i t h p l e a s u r e by a l l , u n t i l a  t h o u g h t f u l o l d mouse got up and s a i d , p l a n a very c l e v e r one. who  The  "I c o n s i d e r the  But I should l i k e to know,  i s going t o put the b e l l on the c a t ? "  [It i s  e a s i e r to make a s u g g e s t i o n than t o c a r r y i t out.] The sentences i n b r a c k e t s served as frame and were not analyzed. The passage was  broken up i n t o the f o l l o w i n g phrases  f o r purposes of a n a l y s e s : Phrase 1 .  a number of mice c a l l e d a meeting,  Phrase 2 .  t o d e c i d e upon the b e s t means  Phrase 3 .  o f r i d d i n g themselves of a c a t  Phrase 4.  t h a t had k i l l e d so many of them.  Phrase 5 .  V a r i o u s p l a n s were t a l k e d  Phrase 6 .  but none of them chosen.  Phrase 7 .  A young mouse came forward, -  101  -  about,  -  Phrase  8.  and  said  that  tyrant's Phrase  9.  Then be  a  b e l l  would  to  Phrase  10.  The  Phrase  11.  u n t i l  Phrase  12.  "I consider  Phrase  13.  But  I  the  b e l l  a l l hear  be  hung  round  the  thoughtful  should on  t h e c a t coming,  and  so  escape.  s u g g e s t i o n was a  should  neck.  they  able  102 -  received o l d mouse  the plan like the  with  a  very  t o know, cat?"  pleasure by  g o t up clever  who  and  a l l .  said,  one."  i s going  t o put  Appendix C Screening  Passage  We know t h e s h o c k s a r e p a i n f u l ; we h a v e o u r s e l v e s and we know t h a t the  p e r s o n who does t h e s h o c k i n g  successfully sive  too.  w i t h a hundred k i d s ,  about i t ; you always t h i n k  e x c e p t i o n ; maybe y o u w i l l But  they hurt.  tried  them on  But i t i s s t r e s s f u l f o r You may h a v e u s e d  b u t you a r e s t i l l  shock  apprehen-  t h a t maybe t h i s k i d w i l l  be t h e  h u r t h i m and i t won't do any g o o d .  t h e n when y o u s h o c k h i m a n d y o u s e e t h e s e l f - d e s t r u c t i v e  behaviour  stop,  i t i s tremendously rewarding.  -  103 -  Appendix Main  Experiment  [Some t i m e ago, a g r o u p to  D Passage  o f mice  of that  p l a n was t a l k e d  awful k i l l e r  tie  a bell  future and  around  they would  s o be a b l e  the tyrant's hear  that  t o escape.  I should l i k e  the  cat?"  The  Many a  that  little  they should  neck.  Then i n  feline  approach  The s u g g e s t i o n was until  a  thoughtful  t h e whole p l a n a c l e v e r one.  t o know, who w i l l  [Iti s easier  put the b e l l  on  t o make a s u g g e s t i o n t h a n  i t out.]  s e n t e n c e s i n b r a c k e t s s e r v e d a s frame  a n d were  analyzed. The  for  "I consider  But  carry  cat.]  crafty  r e c e i v e d w i t h much p l e a s u r e , mouse s a i d ,  themselves  o v e r , when a n i n s i g n i f i c a n t  mouse came f o r w a r d a n d r e m a r k e d  not  a meeting  d e c i d e upon a good means o f r i d d i n g  permanently  to  called  p a s s a g e was b r o k e n  purposes  up i n t o  1:  Many a p l a n was t a l k e d  Phrase  2:  when an i n s i g n i f i c a n t  Phrase  3:  and remarked  Phrase  4:  phrases  of analysis:  Phrase  the  the f o l l o w i n g  tyrant's  that  little  mouse came f o r w a r d  they should t i e a b e l l  around  neck.  Then i n f u t u r e feline  over,  they would  approach  -  104 -  hear t h a t  crafty  -  105 -  Phrase  5:  and so be a b l e  to escape.  Phrase  6:  The s u g g e s t i o n  was r e c e i v e d w i t h  Phrase  7:  until  Phrase  8:  "I consider  Phrase  9:  But I should bell  a t h o u g h t f u l mouse  much  pleasure,  said,  t h e whole p l a n a c l e v e r one. like  on t h e c a t ? "  t o know, who w i l l  put the  Appendix E Main Experiment Sentence  10  /o/  " [ I n an a v e r a g e  Sentences theater  on a s c e n e j u s t Enthralled for  like  actors the  following:]  Maud's c a u t i o u s  the chalk  scrawl  are working  daughter  on t h e w a l l  pauses,  t a l k s of  awesome hawk's c l a w s . [It  i s quite clear that  s u c h s c e n e s must  be c a r e f u l l y e x e c u t e d . ] " Sentence  11  / i /  " [ I n an a v e r a g e t h e a t e r on a s c e n e j u s t Seated East  like  are working  the following:]  i n between l e a f y t r e e s  t h e keen  G r e e n v i l l e people see the three  teams e a c h r e t r e a t [It  actors  greedy  speedily.  i s quite clear that  s u c h s c e n e s must  be c a r e f u l l y e x e c u t e d . ] "  Sentence /a/  12  " [ I n an a v e r a g e t h e a t e r on a s c e n e At  h a l f past  gas masks staff [It  just  like  actors  are working  the f o l l o w i n g : ]  one t h e c a l m f a t h e r  passes  up t h e s h a f t a f t e r t h e c a s t l e  r u s h e d up t h e p a t h .  i s quite clear that  s u c h s c e n e s must  be c a r e f u l l y e x e c u t e d . ] "  -  106 -  -  Sentence /u/  13  107  " [ I n an a v e r a g e a scene  just  Soon t h e two  -  t h e a t e r a c t o r s are working  like  the  following:]  f o o l s who  choose  t o t h e smooth s n o o p s who to shoot snooker [It  i s quite  carefully  The analyzed.  on  use  crude  tools  goof-proof  lose  rules  pool.  clear  that  such  s c e n e s must  be  executed.]"  s e n t e n c e s i n b r a c k e t s s e r v e d as frame and were n o t  Appendix F  Symbols u s e d i n t h e Study Consonants  LabioDental  Bilabial  Plosives  D e n t a l and Alveolar  p,b  Nasals  PalatoAlveolar  Palatal  t,d  m  Laterals Fricatives  p  Frictionless Continuants and Semivowels  w  e,8/s,z  f,v  j , ^  Vowels  front close  back  i  u  i  o e  o  e  e  A O  ae open  v  a  D i a c r i t i c a l Marks:  = unreleased = voicing  v = 0  breath  - 108 -  (  •  ' h  = syllabic =• s t r e s s = aspiration  Velar  Glottal  Appendix' G  600 —  1  3  6  II  14  16 2 0 2 2 2 4 2 7 3 0 3 3 3 8 4 0 4 2 4 6 4 8 51  2  5  10  13  15  19 21  2 3 26 29 32 37  3 9 41  45 47  53 58 63 67 6 9  5 0 52 57 6 2 6 6 6 8 7 0  NORMAL FAST DAF SLOW SLOW DAF  Subject 1 ,  Sentence 12 -  109  -  71 74  -  400  110 -  —  MSEC,  SYL.  1 2  3 6 II 14 16 20 22 24 27 30 33 3 8 4 0 42 4 6 4 8 51 53 58 6 3 6 7 6 9 71 - - - 5 10 13 15 19 21 23 26 29 32 37 3 9 41 4 5 4 7 5 0 52 57 62 6 6 6 8 7 0 74  NORMAL FAST DAF SLOW SLOW DAF  Subject 2,  Sentence 12  -  -  Ill  500  400  300-  200  100 —  MSEC.  0.  SYL.  |  2  3  6  14  5  10 13  15  ,  |  ,  ,  .  |  i  |  •  |-  .  |  i  3 0 3 3 3 8 4 0 4 2 4 6 4 8 51  |  i  |  i  |  16 2 0 2 2 2 4 2 7  19 21 2 3 2 6 2 9 3 2 3 7 3 9 41 4 5 4 7 5 0 5 2 5 7 6 2 6 6 6 8 7 0 NORMAL  S u b j e c t 3,  S e n t e n c e 12  i  5 3 5 8 6 3 6 7 6 9 71  —  FAST  —  SLOW  —  SLOW  DAF  DAF  74  -  112 -  700 —  MSEC.  0 —  SYL.  |  i  |  .  |  I  4  6  9  13  3  5  8  12  ,  |  ,  |  i  |  I  |  ,  |  .  |  i  |  i  |  i  |  15 19 2 4 2 9 3 2 3 5 3 7 41 4 6 4 8 51 5 4 5 9 6 3 6 6 6 9 7 2 7 5 14 18 2 3 2 8 31 3 4 3 6 4 0 4 5 4 7 5 0 5 3 5 8 6 2 6 5 6 8 71 7 4 7 8 NORMAL FAST  DAF  SLOW SLOW  S u b j e c t 1, Sentence 13  DAF  -  113 _  500 —  400 —  300 —  200  -A  - \  -\  V/  \  A  V  I  \\ i I  /  V  100 —  MSEC.  0 —  SYL.  I  |•  i  |  I  |  I  4  6  9  13  15  19 2 4 2 9 3 2 3 5 3 7 41 4 6 4 8 51 5 4 5 9 6 3 6 6 6 9 7 2 7 5  i  |  i  |  I  |  '  | • '  |  i  |  3  5  8  12  14  18 2 3 2 8 31  1  |  3 4 3 6 4 0 4 5 4 7 5 0 5 3 5 8 6 2 6 5 6 8 71  1  74 7 8  NORMAL FAST  DAF  SLOW SLOW  •Subject 2,  Sentence 13  |  DAF  -  iiU -  600 —  MSEC  |  I  |  I  |  I  |  I  |  I  |  I  |  I  |  I  |  I  |  I  |  I  |  I 4 6 9 13 15 19 24 29 32 35 37 4J 46 48 51 54 59 63 66 69 72 7! SYL.  3 5 8 12 14 18 23 28 31 34 36 40 45 47 50 53 58 62 65 68 71 74 78 NORMAL FAST DAF SLOW SLOW DAF  Subject 3,  Sentence 13  400 —  SEG.  | I I I | I I I I | I I I I | I II I 5 10 15  Subject 1, Sentence 12  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 I |I I M | I I I I | I 20 25 30 35 40 45 50 55 60 65 70 NORMAL FAST DAF  

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