UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

An investigation of sound attentuation by tree stands Matthews, John Russel 1971

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Notice for Google Chrome users:
If you are having trouble viewing or searching the PDF with Google Chrome, please download it here instead.

Item Metadata

Download

Media
831-UBC_1971_A6 M38.pdf [ 15.73MB ]
Metadata
JSON: 831-1.0101911.json
JSON-LD: 831-1.0101911-ld.json
RDF/XML (Pretty): 831-1.0101911-rdf.xml
RDF/JSON: 831-1.0101911-rdf.json
Turtle: 831-1.0101911-turtle.txt
N-Triples: 831-1.0101911-rdf-ntriples.txt
Original Record: 831-1.0101911-source.json
Full Text
831-1.0101911-fulltext.txt
Citation
831-1.0101911.ris

Full Text

I N V E S T I G A T I O N O F S O U N D A T T E N U A T I O N BY T R E E S T A N D S by . R U S S E L M A T T H E W S B.Sc. (HONS) University of Wales, 1968 A T H E S I S S U B M I T T E D ' I N P A R T I A L F U L F I L M E N T O F T H E R E Q U I R E M E N T S F O R T H E D E G R E E O F M A S T E R O F F O R E S T R Y i n the Faculty of F O R E S T R Y We accept this thesis as conforming to the required standard T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A A p r i l 1 9 7 1 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l - make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y - . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may b e g r a n t e d b y t h e H e a d o f my D e p a r t m e n t o r b y h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s ' t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t b e a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . F a c u l t y o f F O R E S T R Y T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r 8 , C a n a d a D a t e j<*/:'fydL' (°cfl A B S T R A C T T h e t h e s i s h a d t w o m a i n o b j e c t i v e s : n a m e l y t o p r o v i d e i n f o r m a t i o n o n t h e s o u n d a t t e n u a t i n g a b i l i t i e s o f t r e e s p e c i e s o f t h e l o w e r m a i n l a n d r e g i o n o f B r i t i s h C o l u m b i a a n d t o a s c e r t a i n w h a t s t a n d c h a r a c t e r i s t i c s c a u s e t r e e s t o a t t e n u a t e s o u n d . A f t e r a n e x t e n s i v e l i t e r a t u r e r e v i e w a n e x p e r i m e n t w a s d e s i g n e d t o i n v e s t i g a t e s o u n d a t t e n u a t i o n i n e i g h t e e n t r e e s t a n d s , c o m p r i s e d o f f o u r s p e c i e s , a t t h r e e d i s t a n c e s , f o r e i g h t d i f f e r e n t s o u n d f r e q u e n c i e s . T h e e x e r i m e n t a l w o r k w a s d o n e d u r i n g t h e w i n t e r o f 1 9 6 9 a n d t h e s u m m e r o f 1 9 7 0 . P r i o r t o t h i s t h e t r e e s t a n d s w e r e e n u m e r a t e d a n d v a r i o u s t r e e p a r a m e t e r s m e a s u r e d . No p a t t e r n s c o u l d b e f o u n d w h i c h s i g n i f i c a n t l y c o r r e l a t e d t h e m e a s u r e d s t a n d c h a r a c t e r i s t i c s w i t h t h e a m o u n t o f s o u n d a t t e n u a t e d . L i t t l e s i g n i f i c a n t d i f f e r e n c e w a s f o u n d b e t w e e n t h e s u m m e r a n d w i n t e r a t t e n u a t i o n s a n d i t w a s f o u n d t h a t s t a n d s r e a c t e d i n d e p e n d e n t l y o f t h e s e a s o n . T a b l e s a r e p r e s e n t e d i n t h e A p p e n d i x s h o w i n g t h e a t t e n u a t i o n s f o r e a c h s t a n d , a t e a c h d i s t a n c e a n d f o r e a c h f r e q u e n c y . M e a n v a l u e s t o g e t h e r w i t h t h e i r s t a n d -a r d d e v i a t i o n s a r e g i v e n f o r a l l s t a n d s w i t h i n a s p e c i e s . S u g g e s t i o n s a r e g i v e n f o r f u t u r e w o r k o n t h i s t o p i c a n d t h e i m p l i c a t i o n s o f t h e r e s u l t s o n v a r i o u s d e s i g n f i e l d s a r e d i s c u s s e d . i i T A B L E O F C O N T E N T S P a g e A B S T R A C T i i T A B L E O F C O N T E N T S i i i L I S T O F T A B L E S . . v i L I S T O F F I G U R E S v i i . G L O S S A R Y i x A C K N O W L E D G M E N T S . . . . . . . . ' . . . . . . x i F R O N T I S P I E C E . . . . . . . . . . . . ' x i i C h a p t e r I - I N T R O D U C T I O N . . . . . . . . . . . . . . . 1 1.1 W h y T h i s P r o b l e m 3 1 . 2 P r e l i m i n a r y O b j e c t i v e s 3 1 . 3 P r a c t i c a l V a l u e 3 1 . 4 A c a d e m i c V a l u e . . . . . . . . . . . . . . 3 C h a p t e r I I - L I T E R A T U R E - . R E V I E W ' 5 2.1 P h y s i c s o f S o u n d 5 2 . 2 W h a t i s N o i s e ? 9 2 . 3 W h a t A r e t h e E f f e c t s o f N o i s e . . . . . . 1 6 2 . 3 . 1 G e n e r a l 1 6 2 . 3 . 2 P h y s i c a l . . . . . . . . . . . . . . . 1 7 2 . 3 . 3 P h y s i o l o g i c a l 1 8 2 . 3 . 4 P s y c h o l o g i c a l 1 9 • 2 . 4 How C a n N o i s e b e A t t e n u a t e d ? . . . . . . . 2 0 2 . 4 . 1 I n v e r s e s q u a r e l a w . . 2 0 2 . 4 . 2 A i r a b s o r p t i o n . 21 2 . 4 . 3 G r o u n d r e f l e c t i o n . 21 2 . 4 . 4 C I i m a t o l o g i c a l e f f e c t s . 2 2 2 . 4 . 5 A t t h e s o u r c e 2 4 2 . 4 . 6 A t t h e . l i s t e n e r . . . . . . . . . . . . 2 5 2 . 4 . 7 B y c o n t r o l l i n g t h e d i r e c t i o n . . . . . . 2 6 2 . 4 . 8 B y t h e u s e o f b a r r i e r s . . . . . . . . 2 7 . P a g e C h a p t e r I I I - D I S C U S S I O N O F P R O C E D U R E S 3 8 3.1 T h e o r i e s a n d H y p o t h e s e s . 3 8 3 . 2 E x p e r i m e n t a l D e s i g n 4 0 3 . 3 L i m i t a t i o n s . . . . . . . . . 4 4 3 . 4 A n a l y s i s . 4 5 C h a p t e r I V - E X P E R I M E N T A L T E C H N I Q U E S . .. . 4 7 4.1 A p p a r a t u s . . . . . 4 7 4 . 2 P r o c e d u r e 4 8 4 . 2 . 1 P l o t m e a s u r e m e n t 4 8 4 . 2 . 2 A t t e n u a t i o n m e a s u r e m e n t 5 2 4 . 2 . 2 . 1 M e a s u r e m e n t t h r o u g h t r e e s c r e e n s . . 5 3 4 . 2 . 2 . 2 M e a s u r e m e n t o v e r o p e n g r o u n d . . . . 5 6 4 . 3 C I i m a t o l o g i c a l F a c t o r s . . . . . . . . . . . 5 6 4 . 3 . 1 T e m p e r a t u r e a n d r e l a t i v e h u m i d i t y . . . 5 6 4 . 3 . 2 W i n d . . . . . . . . . . . . . 5 7 4 . 3 . 3 O t h e r s . 5 8 4 . 4 E x p e r i m e n t a l E r r o r s . 5 8 4 . 4 . 1 P e r s o n a l a n d I n s t r u m e n t a l . . . . . . . . 5 8 4 . 5 R e p r o d u c i b i l i t y . . . 5 9 C h a p t e r V - P U R P O S E O F A N A L Y S E S AND D A T A F O R M A T . . . . 6 0 5.1 P u r p o s e o f t h e A n a l y s e s a n d D a t a F o r m a t . . 6 0 5 . 2 C o d i n g 6 0 5 . 3 T h e A n a l y s e s . . . . . . . . . . . . . . • . 6 2 C h a p t e r V I - R E S U L T S AND D I S C U S S I O N . 6 5 6.1 M e t h o d o f P r e s e n t a t i o n . . 6 5 6.2 M u l t i p l e R e g r e s s i o n A n a l y s i s . . . . . . . . 6 5 6 . 3 T h e I n v e r s e S q u a r e L a w 71 6 . 4 A t t e n u a t i o n V a l u e s . . . . . . . . . . . . ; 7 2 6 . 5 T h e A n a l y s e s o f V a r i a n c e 7 3 6 . 6 T h e T w o - W a y A n a l y s i s o f V a r i a n c e . . . . . . 8 2 C h a p t e r V I I - I M P L I C A T I O N S O F R E S U L T S . . . . . . . . . . 8 8 7.1 I n t r o d u c t i o n . . ..; . . . . . . 8 8 7 . 2 L a n d s c a p e D e s i g n 8 8 7 . 3 I n d u s t r i a l D e s i g n . . . . . . . . . . . . . 9 0 7 . 4 H i g h w a y D e s i g n 9 3 7 . 5 R e c r e a t i o n a n d P a r k D e s i g n . . . . . . . . . . 9 6 . 7.6 • U r b a n D e s i g n . . . . . . . . . . 9 7 P a g e C h a p t e r V I I I - S U G G E S T I O N S F O R F U T U R E WORK AND C O N C L U S I O N S . . . . . . . . . . . . . 1 0 0 8.1 S u g g e s t i o n s f o r F u t u r e W o r k 1 0 0 8 . 1 . 1 M a n a g e d s t a n d s . . . . . . 1 0 0 8 . 1 . 2 A r t i f i c i a l s t a n d s . . . . . . . . . . . . 1 0 1 8 . 1 . 3 T o t e s t t h e t h e o r y o f d i m i n i s h i n g a t t e n u a t i o n c o e f f i c i e n t s a n d t h e i n v e r s e s q u a r e l a w 1 0 2 8 . 1 . 4 H e i g h t o f t h e s o u n d s o u r c e 1 0 2 8 . 1 . 5 O t h e r f a c t o r s 1 0 3 8 . 1 . 6 T h e w h i t e c a r d t e c h n i q u e f o r e s t i m a t i n g g r o u n d v e g e t a t i o n . . . ., 1 0 3 8 . 1 . 7 S h r u b s p e c i e s 1 0 3 8 . 2 C o n c l u s i o n s 1 0 4 A P P E N D I X 1 . M a p S h o w i n g L o c a t i o n o f T r e e S t a n d s . . . - . . . 1 0 6 2 . S t a n d I n f o r m a t i o n f o r t h e F o u r S p e c i e s . . . . . 1 0 8 3 . S u m m e r a n d W i n t e r C o r r e l a t i o n M a t r i c e s 1 1 4 4 . A t t e n u a t i o n V a l u e s f o r t h e F o u r S p e c i e s . . . . . 1 2 4 5 . B l a c k a n d W h i t e P h o t o g r a p h s o f t h e T r e e S t a n d s . 1 3 8 B I B L I O G R A P H Y . 1 5 7 T a b l e P a g e 1 . D e c i b e l S c a l e . . 1 2 2 . N o i s e L e v e l s i n D i f f e r e n t V e h i c l e s 1 3 3 . E x a m p l e s o f D i f f e r e n t N o i s e L e v e l s . . . . . . 1 3 4. M a x i m u m N o i s e L e v e l s A c c e p t e d i n S w i t z e r l a n d 1 4 5 . P e r m i s s i b l e N o i s e E x p o s u r e s i n t h e U n i t e d S t a t e s o f A m e r . i c a 1 5 6. A t t e n u a t i o n s a t 1 0 0 F e e t O b t a i n e d f r o m E y e r i n g ' s R e s u l t s . 2 9 7 . C o m p a r i s o n o f t h e R e s u l t s o f E y e r i n g w i t h T h o s e o f W i e n e r a n d K e a s t 3 0 8. A t t e n u a t i o n s O b t a i n e d b y M e i s t e r i n 1 9 5 9 f o r V a r i o u s V e g e t a t i o n T y p e s . . . . 31 9. A t t e n u a t i o n s P r o d u c e d b y D i f f e r e n t S p e c i e s 3 6 1 0 . C o m p a r i s o n o f A t t e n u a t i o n C o e f f i c i e n t s . . . . 7 9 F i g u r e P a g e 1. G r a p h i c a l D e p i c t i o n o f E y e r i n g ' s R e s u l t s . . . 2 8 2 . G r a p h i c a l D e p i c t i o n o f W i e n e r a n d K e a s t ' s R e s u l t s 3 0 3 . G r a p h o f D e c i b e l s M e a s u r e d A g a i n s t F r e -q u e n c y a s O b t a i n e d b y H e s s a n d K u r s t e i n e r . 3 2 4 . G r a p h s o f A t t e n u a t i o n A g a i n s t F r e q u e n c y f o r A l l F o u r , S p e c i e s a s O b t a i n e d . b y E m b l e t o n 3 3 5 . G r a p h s o f A t t e n u a t i o n A g a i n s t F r e q u e n c y f o r I n d i v i d u a l S p e c i e s a s O b t a i n e d b y E m b l e t o n 3 4 6. G r a p h i c a l R e s u l t s o f E m b l e t o n ' s T e s t f o r R e s o n a n c e 3 4 7 . G r a p h i c a l R e s u l t s o f E m b l e t o n ' s A t t e m p t t o C o r r e l a t e O p t i c a l V i s i b i l i t y w i t h S o u n d A t t e n u a t i o n . . . . 3 5 8 . D i a g r a m a t i c R e p r e s e n t a t i o n o f • t h e E x p e r i m e n t a l D e s i g n . . . . . . 41 9 . G r a p h S h o w i n g t h e R e s p o n s e o f t h e S o u n d L e v e l M e t e r S e t t i n g s w i t h R e s p e c t t o F r e q u e n c y . . 4 3 1 0 . S c h e m a t i c P l a n o f t h e A p p a r a t u s . . . . . . . . 5 4 1 1 . G r a p h o f A t t e n u a t i o n i n D e c i b e l s 'A'. A g a i n s t F r e q u e n c y f o r D o u g l a s f i r . . . . 7 4 1 2 . G r a p h o f A t t e n u a t i o n i n D e c i b e l s 'A' A g a i n s t F r e q u e n c y f o r t h e M i x t u r e . . . . 7 5 F i g u r e P a g e 1 3 . G r a p h o f A t t e n u a t i o n i n . D e c i b e l s 'A' A g a i n s t F r e q u e n c y f o r B i r c h . . . . . . . 7 6 . 1 4 . G r a p h o f A t t e n u a t i o n i n D e c i b e l s 'A' A g a i n s t F r e q u e n c y f o r A l d e r 7 7 1 5 . G r a p h o f A t t e n u a t i o n i n D e c i b e l s 'A' f o r E a c h ' S t a n d i n E a c h S e a s o n f o r D o u g l a s f i r . . . . . . . . . . . . . . 8 3 1 6 . G r a p h o f A t t e n u a t i o n i n D e c i b e l s 'A' f o r E a c h S t a n d i n E a c h S e a s o n f o r t h e M i x t u r e 8 4 1 7 . G r a p h o f A t t e n u a t i o n i n D e c i b e l s 'A' f o r E a c h S t a n d i n E a c h S e a s o n f o r B i r c h 8 5 1 8 . G r a p h o f A t t e n u a t i o n i n D e c i b e l s 'A' f o r E a c h S t a n d i n E a c h S e a s o n f o r A l d e r . . . . . . . . . . . . . . . . - . 8 6 1 9 . G r a p h S h o w i n g L e v e l s a n d S p e c t r a o f I n d u s t r i a l N o i s e • • 9 2 2 0 . G r a p h S h o w i n g L e v e l s a n d S p e c t r a o f H i g h w a y N o i s e 9 2 2 1 . G r a p h S h o w i n g L e v e l s a n d S p e c t r a o f R e s i d e n t i a l N o i s e 9 8 v i i i G L O S S A R Y The decibel - T w o s o u n d s o f e n e r g i e s a n d W 2 a r e s a i d t o d i f f e r b y n d e c i b e l s ( d B ) w h e n n = 1 0 l o g i c ( W : / W ? ) . B y e x t e n s i o n , t w o s o u n d p r e s s u r e s p a a n d p 2 d i f f e r b y n d e c i b e l s w h e n n = 20 l o g i o (Pi/Pz) • T h u s a d e c i b e l i s n o t a q u a n t i t y b u t a r e l a t i o n b e t w e e n t w o q u a n t i t i e s . E x p r e s s i o n s l i k e "90 d e c i b e l s " w h i c h a r e s o c o m m o n l y u s e d a r e t h e r e f o r e m e a n i n g l e s s u n l e s s r e l a t e d t o a d a t u m . I f n o d a t u m i s e x p l i c i t l y s t a t e d t h e r e f e r -e n c e s o u n d p r e s s u r e o f 0.0002 d y n / c m 2 i s u s u a l l y i m p l i e d . A n i n c r e a s e o f 3 d B m e a n s t h a t t h e n o i s e e n e r g y i s d o u b l e d ; a n i n c r e a s e o f 10 d B m e a n s . a t e n f o l d e n e r g y i n -c r e a s e , a n d s o o n . Frequency - i s t h e r a t e o f r e p e t i t i o n o f a p e r i o d i c p h e n o m e n o n a n d i s m e a s u r e d i n c y c l e s / s e c o n d ( c / s ) . S'ound pressure level - i s measured i n d e c i b e l s r e l a t i v e to a datum l e v e l of 0.0002 d y n / c m 2 . ' Pitch - i s the s u b j e c t i v e e q u i v a l e n t of f r e q u e n c y . Loudness - i s the s u b j e c t i v e e q u i v a l e n t of i n t e n -s i t y , d e f i n e d as a " l i s t e n e r ' s a u d i t o r y i m p r e s s i o n of the s t r e n g t h of a s o u n d . " A C K N O W L E D G M E N T S I w o u l d T i k e t o t h a n k f i r s t l y T h e N a t r o n a T R e s e a r c h C o u n c i l , O t t a w a , w h o p r o v i d e d t h e f i n a n c i a l s u p p o r t f o r t h e p r o j e c t . M a n y p e o p l e p r o v i d e d a s s i s t a n c e , t h e t e c h -n i c i a n s i n t h e E l e c t r i c a l E n g i n e e r i n g d e p a r t m e n t , , t h e -m e m b e r s o f my t h e s i s c o m m i t t e e , M r . P . J . D o . o l i h g , D r . D. H a l e y , D_r. A . K o z a k , D r . J . N e i l l a n d M r . P. T a t t e r s f i e l d , t h e D i r e c t o r o f t h e U . B . C . R e s e a r c h F o r e s t , M r . J . W a l t e r s , t h e f i e l d a s s i s t a n t s , M r . D a v i d S m i t h a n d M r . M e l v y n M o f f a t . A l l o f t h e s e p e o p l e h e l p e d d u r i n g o n e p h a s e o r , a n o t h e r o f t h e p r o j e c t . I w o u l d a l s o l i k e t o e x t e n d my h e a r t f e l t t h a n k s t o a n u m b e r o f p e o p l e w h o o f f e r e d n o t e c h n i c a l a d v i c e , s o l v e d n o p r o b l e m s b u t w h o b e t w e e n t h e m m a n a g e d t o m a k e i n s u r m o u n t a b l e p r o b l e m s s o l v a b l e . T o M r . E r y l P a r d o e , M i s s L i l y A n n M a r s h a l l a n d t o a l l t h e f o r e s t r y g r a d u a t e s t u d e n t s m a y I s a y a n e s p e c i a l t h a n k y o u , a n d t o S h a r i H a l l e r w h o t y p e d t h e m a n u s c r i p t . . From a l l destroyers of natural beauty in this parish and everywhere, from a l l .. p o l l u t e r s of earth, air and water, from a l l makers of v i s i b l e abominations, from j ' e r r y - b u i l d e r s , d i s f i g u r i n g advertisements, road-hogs, and spreaders of l i t t e r , from the v i l l a n i e s of the rapacious and the in-competencies of the stupid, from careless-ness of i n d i v i d u a l s and the somnolence of local a u t h o r i t i e s , from a l l foul smells, noises, and sights.... good Lord d e l i v e r us! ( C o u n c i l f o r t h e p r e s e r v a t i o n o f R u r a l E n g l a n d , 1 936) Chapte r I I N T R O D U C T I O N 1 . 1 Why Th i s P rob lem S e l e c t i n g a t h e s i s t o p i c i s somewhat s i m i l a r to s e l e c t i n g a w i f e . A t h e s i s i s someth ing you l i v e w i t h f o r about two y e a r s o f you r l i f e and t h e r e f o r e i f i t and the r e s e a r c h e r a re go ing to have a s u c c e s s f u l r e l a t i o n s h i p they need to be c o m p a t i b l e . The t h e s i s needs , as do a l l women, an a i r o f f a s c i n a t i o n , an aura of i n t r i g u e , an a b i l i t y to a rouse the c u r i o s i t y , and hav i n g a roused i t , an a b i l i t y to s u s t a i n i t . S ad l y a l l too few the se s have t h i s c a p a b i l i t y and perhaps the same may be s a i d f o r the m a j o r i t y o f women. The above ment ioned r e q u i r e m e n t s may be added to ano the r s e t of d i c t a t e s - tho se of s o c i e t y . D i r e c t l y or i n d i r e c t l y s o c i e t y f i n a n c e s a l l r e s e a r c h and t h i s t h e s i s i s no e x c e p t i o n . In r e t u r n f o r i t s s uppo r t s o c i e t y o f t e n makes c e r t a i n demands: I t asks t h a t a t h e s i s be u s e f u l , a p p l i c a b l e , and l a s t but not l e a s t - needed.. These c r i t e r i a l e a d to the s e l e c t i o n of a t h e s i s wh ich would i n v e s t i g a t e - t he ' s ound a t t e n u a t i n g a b i l i t i e s of t r e e s c r een s and the p a r t i c u l a r s t and c h a r a c t e r i s t i c s wh ich cause a t t e n u a t i o n . I n f o r m a t i o n cn the a b i l i t y of a t r e e s t and to reduce sound i s needed by many groups and would be u s e f u l in - the f i e l d s of highway d e s i g n , urban d e s i g n , i n d u s t r i a l l o c a t i o n and d e s i g n , and to the more g e n e r a l f i e l d of l a nd s cape d e s i g n . The r e s u l t s f rom t h i s s t udy w i l l be a p p l i c a b l e to the h i g h l y p o p u l a t e d a rea s of the Vancouver and S e a t t l e m e t r o p o l e s . No i s e . ha s a lways been a prob lem to mank.i.n.d. However i n r e c e n t y e a r s the prob lem has i n c r e a s e d enormous ly and now a f f e c t s each and eve ry one of us . Our r o a d s i d e r e c r e a -t i o n a rea s a re no l o n g e r q u i e t , f a c t o r i e s produce n o i s e which d i s t u r b s nearby r e s i d e n t s , our c i t i e s a re becoming d e a f e n i n g i n some a r e a s , and highway and a i r p o r t n o i s e a re r e n d e r i n g l a r g e t r a c t s of n e i g h b o u r i n g l and u n f i t f o r human h a b i t a t i o n . The prophesy made i n 1880 by Rober t Koch t h a t " . . . o n e day n o i s e w i l l be f ough t l i k e we are. c u r r e n t l y f i g h t i n g c h o l e r a and the p l a g u e " (Zundel -1 965 ) i s s t a r t i n g to come t r u e . In the vanguard of the f i g h t have been a few worke r s who have a t t empted to i n v e s t i g a t e v a r i o u s ways i n wh ich t r e e s can be used to reduce n o i s e . These worke r s have i n c l u d e d Wiener and Keast ( 1 9 5 9 ) , Hess and K u r s t e i ner (1961 ) , Embleton and Thi.essen ( 1 9 6 2 ) , Durk (1 9 6 5 ) , Swieboda (.19.65), Zundel (1 9 6 5 ) , Anderson (1 969 ), Cook and Haverbecke (1 969 ),. and R o b i n e t t e (1 969 ). A r e v i e w of t h e i r work and o t h e r s i s to be found i n Chap te r I I . 1 • 2 P r e l i m i n a r y O b j e c t i v e s The i n i t i a l o b j e c t i v e s o f t h i s t h e s i s were to i n v e s -t i g a t e and q u a n t i f y the sound a t t e n u a t i o n at v a r i o u s f r e -quenc i e s of s c r e e n s of t r e e s composed of d i f f e r e n t s p e c i e s ; and to a t t empt to c o r r e l a t e t h i s a t t e n u a t i o n w i t h v a r i o u s measured c h a r a c t e r i s t i c s of the t r e e s tand a n d . i t s a s s o -c i a t e d ground v e g e t a t i o n . « 1.3 P r a c t i c a l Va l ue The p r a c t i c a l v a l u e of the t h e s i s l i e s i n i t s a b i l i t y to p r o v i d e d e f i n i t e i n f o r m a t i o n about f o u r s tand t ype s found i n the l ower ma i n l and r e g i o n of B r i t i s h C o l u m b i a . Shou ld l a r g e v a l u e s be o b t a i n e d f o r the sound a t t e n u a t i o n , t h i s i n f o r m a t i o n would be of enormous impo r tance i n numerous d e s i g n f i e l d s , and the i m p l i c a t i o n s of the r e s u l t s w i l l be d i s c u s s e d l a t e r i n the t h e s i s . 1 .4 -Academic Va l ue In a l l the work done to da te on the sound a t t e n u a t i n g a b i l i t i e s of t r e e s c r e e n s , no one ha s , as y e t , a t t empted to c o r r e l a t e a t t e n u a t i o n and measured f a c t o r s of the t r e e s tand o t h e r than o p t i c a l v i s i b i l i t y (.Embl e t o n , 1 9 63 ) . H o p e f u l l y , t h i s t h e s i s w i l l p r o v i d e a t e c h n i q u e t h a t w i l l e nab l e t h i s to be done and f u r t h e r w i l l g i v e an i n d i c a t i o n as to wh ich s tand c h a r a c t e r i s t i c s cause sound a t t e n u a t i o n . The e x p e r -i m e n t a l d e s i g n w i l l be such t h a t , g i v e n s u i t a b l e a p p a r a t u s , the t e s t s c o u l d be r e p r o d u c e d , to p r o v i d e i n f o r m a t i o n , f o r t r e e s tands found i n any p a r t o f the w o r l d . Chapte r I I L I T E R A T U R E R E V I E W 2•• 1 The P h y s i c s of Sound Sound i n gene ra ted by a v i b r a t i n g body. These v i b r a t i o n s s e t up waves of compre s s i on and r a r e f r a - c t i on i n the s u r r o u n d i n g a i r . The sound waves move outward i n a s e r i e s of m inute push and p u l1 m o t i o n s , each push c o r -r e s p o n d i n g to a compres s i on and each p u l l to a r a r e f r a c -t i o n . When the waves r each the e a r , the push p u l l e f f e c t s t a r t s a second s e t of v i b r a t i o n s w h i c h , i n t u r n , a f f e c t the a u d i t o r y nerve g e n e r a t i n g the s e n s a t i o n we c a l l h e a r i n g The human body and mind make c e r t a i n p h y s i o l o g i c a l and p s y c h o l o g i c a l r e sponse s to t h i s i n i t i a l mechan i c a l s t i m u l u s ' These r e spon se s w i l l be s t u d i e d l a t e r i n more d e t a i l . The energy of a sound wave i s sma l l and a sound i t s e l f i s s h o r t l i v e d . The energy of the wave i s o b v i o u s l y be i ng t r a n s f e r r e d i n t o ano the r form - u s u a l l y h e a t . An example of the s m a l l energy of sound waves i s g i v e n by R..L. Jones i n B e l l Te lephone D i r e c t o r y . . . if a m i l l i o n persons were.to t a l k • s t e a d i l y and the energy of t h e i r voices converted into heat, they would have to t a l k for an hour and a half to produce enough heat, to make a cup of tea. So much f o r the t h e o r y t h a t the l e i s u r e t ime of women c o u l d be put to some u s e f u l pu rpose ! To r e c e i v e the se minute q u a n t i t i e s of energy and t r a n s f e r them i n t o the s e n s a t i o n of h e a r i n g , the ear must need to be a r ema rkab l e s e n s i t i v e i n s t r u m e n t . Though the q u a n t i t i e s of energy a r e , r e l a t i v e l y s p e a k i n g , v e r y s m a l l , they va r y enormous ly between the q u i e t e s t and the l o u d e s t sounds. An a r t i c l e p u b l i s h e d by the M a s s a c h u s e t t s Audubon S o c i e t y ( 1 968 ) , equated the h e a r i n g a b i l i t y of the ear w i t h t h a t of a b a l ance a b l e to weigh both a pos tage stamp and an o c e a n ' l i n e r . The v a r i a t i o n s i n energy . l e v e l s produce the e f -f e c t s of l oud and q u i e t sounds. However the r e l a t i o n s h i p i s not a d i r e c t one. The amount of energy per s e c o n d , p a s s i n g th rough a one c e n t i m e t r e s q u a r e , p e r p e n d i c u l a r to the wave d i r e c t i o n , i s the sounds i n t e n s i t y and i s p r o p o r t i o n a l to the square of the p r e s s u r e v a r i a t i o n . The s e n s a t i o n of l oudne s s i s n e a r l y p r o p o r t i o n a l to the l o g a -r i t h m of t h i s i n t e n s i t y . 1 0 " 1 6 wa t t s per second i s the i n t e n s i t y of the f a i n t e s t a u d i b l e sound and has an i n t e n -s i t y l e v e l ( l o u d n e s s ) of 0 d e c i b e l s (DB . ) . An i n t e n s i t y of 1 0 ~ 1 5 w a t t s per second i s 10 t imes as i n t e n s e as the t h r e s -h o l d and has an i n t e n s i t y l e v e l . o f 10 DB. An i n t e n s i t y o f TO" 1 1 * w a t t s per second i s 10 t imes as i n t e n s e as IO" ' 1 ' 5 w a t t s per s e c o n d , 100 t imes as i n t e n s e as the t h r e s h o l d and has an i n t e n s i t y l e v e l of 2 0 D B . However the 2 0 D B . sound i s not 1 0 0 t imes as l oud as the t h r e s h o l d . S i n c e i n t e n s i t y l e v e l i s , by d e f i n i t i o n , a l o g a r i t h m i c f u n c t i o n , the s e n s a t i o n of l oudnes s i s a p p r o x i m a t e l y p r o p o r t i o n a l to the i n t e n s i t y l e v e l i n d e c i b e l s ( A n t h r o p , 1 9 6 9 ) . Thus the l oudnes s of the 20 D B . Sound exceeds t h a t of the 1 0 D B . sound by the same amount t h a t the l oudnes s of the 1 0 D B . sound exceeds t h a t of the t h r e s h o l d of h e a r i n g . A sound has ano the r c h a r a c t e r i s t i c - b e s i d e s i t s i n t e n s i t y . Th i s i s i t s f r e q u e n c y , and i s d e f i n e d as the . number of c y c l e s of the wave wh ich pass th rough a g i v e n p o i n t i n one s e cond . The l o w e s t note on a p iano has a f r e q u e n c y of 3 0 c y c l e s per s e cond , c o n v e r s a t i o n ranges between 2 0 0 and 6 , 0 0 0 c y c l e s per s e c o n d , and the l i m i t of h e a r i n g f o r a young h e a l t h y a d u l t male i s around 1 2 , 0 0 0 t o 1 4 , 0 0 0 c y c l e s per s econd . Above t h i s l e v e l the f r e q u e n c y i s i n the range whe re , as F l a n d e r s and Swan put i t , . . . the ear can't hear as high as that but i t ought to please any passing bat.. ( B r a gdon , 1 9 6 8 ) . G e n e r a l l y the h i gh f r e q u e n c y sounds we can hear seem l o u d e r to us , and a r e more d i s t u r b i n g , d e c i b e l f o r d e c i b e l , than the low f r e q u e n c y sounds ( M a s s a c h u s e t t s Audubon S o c i e t y , 1 9 6 8 ) . I n f o r m a t i o n f o r t h i s p o r t i o n of the t e x t was o b t a i n e d f rom the t e x t " Sound " (Watson, 1 9 3 5 ) . Between the p r o p a g a t i o n and r e c e p t i o n of a sound any one of a number of f a c t o r s may have a l t e r e d i t s f o r m . Each of these w i l l be b r i e f l y d i s c u s s e d . P i f f r a c t i o n - I f a l i g h t f rom a p o i n t s ou rce i s shone th rough an open ing onto a s c r e e n , the edges of the l i g h t on the s c r e e n w i l l have a b l u r r e d e f f e c t . Th i s i s caused by the bend ing of the l i g h t waves as they pass the edge of the o p e n i n g . The same p r i n c i p l e a p p l i e s , to a g r e a t e r e x t e n t , w i t h sound waves. Th i s phenomenon i s known as d i f f r a c t i o n , and the amount of s p r e a d i n g i n c r e a s e s as the s i z e of the open ing becomes s m a l l e r , compared w i t h the wave l e n g t h . R e f 1 e c t i o n - Du r ing i t s passage from sou rce to r e c e p t o r , a sound may encoun te r an i n t e r v e n i n g s c r e e n . The waves w i l l h i t t h i s s c r e e n and , wi11 be bounced o f f i n a manner s i m i l a r to t h a t of a b a l l e n c o u n t e r i n g a w a l l . T h i s p r oce s s i s known as r e f l e c t i o n . R e f r a c t i o n - I f , i n i t s t r a n s m i s s i o n , a sound wave passes from one medium to a second medium of d i f f e r e n t , d e n s i t y or e l a s t i c i t y , the v e l o c i t y of the wave changes . Th i s causes a bend ing of the waves and i s known as r e f r a c -t i o n . Th i s r e f r a c t i o n may be caused i f the a i r i s u n e q u a l l y h e a t e d , or i f a wind i s b l ow i n g such t h a t i t s v e l o c i t y a t the ground i s l e s s because o f f r i c t i o n . I n t e r f e r e n c e - I f , i n s t e a d of j u s t one s e t of sound waves we c o n s i d e r two s e t s , when they c r o s s each o t h e r they s e t up c e r t a i n e f f e c t s known as i n t e r f e r e n c e . Two equa l compress ion ' s produce a doub le c ompre s s i on , ' two equa l r a r e f r a c t i o n s a doub le r a r e f r a c t i o n , and a compres -s i o n and a r a re ' f r a c t i on tend to annul each o t h e r s e f f e c t . Resonance - A sound wave has a n a t u r a l v i b r a t i o n p e r i o d wh ich v a r i e s w i t h the f r e q u e n c y c f the sound. These v i b r a t i o n s can cause a second, s e t of v i b r a t i o n s of l a r g e a m p l i t u d e (even i f the o r i g i n a l v i b r a t i o n s a re r e l a t i v e l y s m a l l ) i f the second v i b r a t i n g body, has a n a t u r a l • p e r i o d the same, or n e a r l y the same, as the o r i g i n a l s e t of v i b r a -t i o n s . T h i s phenomenon i s known as re sonance and can have an_ a m p l i f y i n g e f f e c t . 2.2 What i s No i se ? . . No i se i s me re l y sound t h a t i s unwanted. I t i s a c h i l d o f the i n d u s t r i a l r e v o l u t i o n , and a b y - p r o d u c t of t e c h n o l o g y ( R o b i n s o n , 1 962 ) ; S c h e n k e r - S p r u n g l i i (1967) r ' epor ted the f o r m a t i o n , i n 1959, of the I n t e r n a t i o n a l A s s o c i a t i o n A g a i n s t N o i s e , and f u r t h e r , equates n o i s e prob lems w i t h tho se of a i r and wa te r p o l l u t i o n . Rob inson (1962) a n d ' S c h a f e r (1969) propose the i dea t h a t n o i s e g i v e s a f e e l i n g o f power and because of t h i s peop le have been w i l l i n g to a c c e p t n o i s e as a n e c e s s a r y b y - p r o d u c t . In an i n v e s t i g a t i o n of the n o i s e i n and around some Japanese s a w m i l l s , S u g i h a r a and K i tayama (1966) p o i n t out the two a s p e c t s of n o i s e problems - namely , n o i s e i n s i d e ' a' f a c t o r y where i t a f f e c t s the emp loyee s , anct n o i s e o u t s i d e the f a c t o r y where i t i s a s o c i a l p rob lem and p u b l i c n u i s a n c e . Embleton and T h i e s s e n (1962) sugges t t h a t n o i s e s h o u l d be one of the f a c t o r s c o n s i d e r e d i n z on i n g d e c i s i o n s Cook and Haverbeke (1969) r e p o r t t h a t the average community sound l « ve1 has r i s e n one d e c i b e l a n n u a l l y f o r the l a s t t h i r t y y e a r s . A p o l i s h w o r k e r , Swieboda (1966) s t a t e d t h a t the f i g h t ' a g a i n s t n o i s e i s not so m u c h a f i g h t to p r o t e c t the a tmosphe re , but r a t h e r the whole b i o l o g i c a l e n v i r o n -ment of man. In an a r t i c l e on n o i s e p o l l u t i o n , the M a s s a c h u s e t t s Audubon S o c i e t y ( 1 9 6 8 ) , sugges ted t h a t r e a c -t i o n s to n o i s e a re more s u b j e c t i v e than r e a c t i o n s to a i r or wa te r p o l l u t i o n . Anderson (1969) s t a t e d t h a t . . . peace and quiet . . . are v i t a l com-ponents of what we now c a l l environmental q u a l i t y . However, he f u r t h e r noted t h a t a n o i s e t h a t i s u n a c c e p t a b l e to one community may be c o m p l e t e l y a c c e p t a b l e , to a n o t h e r . He f u r t h e r emphas i ses the s u b j e c t i v e n a t u r e of n o i s e when he s t a t e s -. . . people who consider, a highway to be obnoxious in general are more, l i k e l y to be annoyed- by highway generated nois-e. E m b l e t o n , Dagg and T h i e s s e n (1959) make the p o i n t t h a t the prob lem of n o i s e i s as much a f u n c t i o n of the f r e q u e n c y as the volume. For example , the t h r e e o c t a v e band's between 600 C .P .S . and 4,800 C .P .S . a re the most e f f e c t i v e i n mask ing the i n t e l l i g i b i l i t y o f s p e e c h . Urban n o i s e goes on w i t h o u t c e a s i n g and h a s ' b e -come l a r g e l y a c c e p t e d ( S c h a f e r , 1 969 ) , ( B r agdon , 1 968 ) . A l t h o u g h t h i s i s the a rea i n wh ich t h e r e e x i s t s the l a r g e s t c o n c e n t r a t i o n s of p e o p l e , i t i s not the o n l y n o i s y p a r t of our e n v i r o n m e n t . P r e v i o u s l y n o i s y work a reas were a s s o c i a t e d w i t h f a c t o r i e s and c o n s t r u c t i o n s i t e s . Today the average o f f i c e may be as n o i s y . a s t he se a reas ( B r agdon , 1968) . 1 Humphreys ( 1 9 6 2 ) , equates n o i s e problems w i t h road a c c i d e n t s , i n t h a t peop le o n l y a c t i v e l y wor ry about them a f t e r they have happened. T h i s s e c t i o n w i l l be c o n c l u d e d w i t h some t a b l e s to i l l u s t r a t e d e c i b e l l e v e l s and some examples of s t a n d a r d s of p e r m i s s i b l e n o i s e . T A B L E 1 D e c i b e l S c a l e D e s c r i p t i o n D e c i b e l L e v e l E x a m p l e E a r d r u m R u p t u r e s 1 4 0 J e t t a k i n g o f f P a i n f u l t o e a r 1 2 0 S i r e n J e t r e v v i n g i t s m o t o r s f o r t a k e o f f T w o e n g i n e p r o p p l a n e D e a f e n i n g 1 0 0 T h u n d e r C a r h o r n a t t h r e e f e e t L o u d p o w e r l a w n m o w e r V e r y l o u d 8 0 P o r t a b l e s a n d e r H a v e t o s h o u t t o b e h e a r d N o i s y c o c k t a i l p a r t y F o o d b l e n d e r I m p o s s i b l e t o u s e t e l e p h o n e L o u d 6 0 V a c u u m c l e a n e r C i t y p l a y g r o u n d A v e r a g e t r a f f i c N o i s y o f f i c e U s e o f t h e t e l e p h o n e d i f f i c u l t M o d e r a t e 4 0 S u b u r b a n p l a y g r o u n d A v e r a g e l i v i n g r o o m F a i n t 2 0 P r i v a t e o f f i c e A w h i s p e r a t f i v e f e e t T h r e s h o l d 0 R u s t l i n g l e a v e s B r e a t h i n g ( A f t e r t h e M a s s a c h u s e t t s A u d u b o n S o c i e t y , 1 9 6 8 ) T A B L E 2 :. N o i s e L e v e l s i n D i f f e r e n t V e h i c l e s T y p e o f . V e h i c l e No i s e I n't e n s i t y i n D e c i b e l s M o t o r c y c l e - n o m u f f l e r no T r u c k , 95 S t r e e t c a r 9 0 S t r e e t c l e a r i n g v e h i c l e 8 3 P a s s e n g e r c a r 7 6 T r o l l e y b u s 7 6 * ( A f t e r S w i e b o d a , 1 9 6 6 ) T A B L E .3 E x a m p l e s o f D i f f e r e n t N o i s e L e v e l s N o i s e S o u r c e . D e c i b e l s L a r g e p n e u m a t i c r i v e t e r 1 2 5 + R o c k a n d r o l l b a n d ( p e a k ) 1 2 0 C o n s t r u c t i o n - n o i s e ( 1 0 f e e t ) 1 1 0 L o u d o u t b o a r d m o t o r 1 0 2 S u b w a y t r a i n ( 2 0 f e e t ) 9 5 + T r a i n w h i s t l e s ( 5 0 0 f e e t ) 9 0 + ( A f t e r W e l c h , 1 9 6 9 ) Maximum No i se L e v e l s A ccep ted i n ' S w i t z e r 1 and Maximum Noise Levels (in decibels) Areas B a s i c Sound F requent Peaks I n f r e q u e n t Peaks R e c r e a t i ona l Eight Day Night Day Night Day 35 45 4 5 50 . 55 55 R e s i d e n t i a l 45 55 55 65 65 70, Commerc i a 1 50 60 60 70 6 5 75 I n d u s t r i a l 55 65 60' 7 5 70 80-. Main t r a f f i c a r t e r i e s 60 70 70 80 :80 • 90 ( A f t e r Schenker S p r u n g ! i i , 1967) Tu rn ing .now to the t o p i c of a c c e p t a b l e n o i s e l e v e l s , Ba r r on ( 1 9 6 9 ) , p r o v i d e s a t a b l e of recommended n o i s e l e v e l s f o r v a r i o u s a rea s r a n g i n g f rom r e s t a u r a n t s to h o s p i t a l s . Bragdon (1968) r e f e r r i n g to the r e p o r t of the subcommit tee on n o i s e i n i n d u s t r y , s t a t e s t h a t the Amer i can Academy of Optha lmo logy and O t o l a r y n g o l o g y recommends n o i s e exposu re c o n t r o l and h e a r i n g t e s t s s h o u l d t h e r e be h a b i t u a l e x p o s u r e , i n the f requency, range, of 300 to 1 ,200 c y c l e s per s e c o n d , to n o i s e s i n exces s of 85 d e c i b e l s . The B r i t i s h M e d i c a l S o c i e t y recommends c o n s e r v a t i o n measures i n the f r e q u e n c y range of 250 to 4,000 c y c l e s per second when the n o i s e l e v e l exceeds 85 d e c i b e l s . (Committee on the Prob lem of N o i s e , 1963.) 1. The U n i t e d S t a t e s A i r Fo rce - ear d e f e n d e r s must be worn i f t h e n o i s e l e v e l - e x c e e d s 85 d e c i b e l s . 2. The s t a t e of New York - a c a r t r a v e l l i n g at 35 M.P.H. must not produce n o i s e i n exces s of 80 d e c i b e l s a t f i f t y f e e t . Recent l e g i s l a t i o n i n the U n i t e d S t a t e s of A m e r i c a , namely the Walsh Hea ley A c t , has produced the f o l l o w i n g t a b l e of pe rm i s . s i b l e n o i s e e x p o s u r e s . » .. TABLE ' 5 P e r m i s s i b l e No i se Exposures i n the U n i t e d S t a t e s of Amer i ca D u r a t i o n per Day ( hou r s ) Sound L e v e l ( d e c i b e l s ' A ' w e i g h t i n g ) 8 90 6 92 4 95 3 97 2 100 1.5 102 1 105 .5 n o .25 or l e s s 115 ( A f t e r O t t , 1970) • . Perhaps the e a r l i e s t l e g a l approach to n o i s e c o n t r o l was t h a t by J u l i u s C a e s a r , who banned n i g h t c h a r i o t d r i v i n g i n the s t r e e t s of Rome, (Mas sachuse t t s Audubon S o c i e t y , 1968) . 2.3 What Are the E f f e c t s of No i se ? 2.3.1 Gene ra l . No i s e has many e f f e c t s and t he se w i l l be examined s h o r t l y under the head ing s - p h y s i c a l , p h y s i o l o g i c a l and p s y c h o l o g i c a l . F i r s t l y a word or two about the o v e r a l l e f f e c t s of n o i s e . S c h a f e r (1969) s t a t e s t h a t i n the U n i t e d S t a t e s of Amer i ca a l o n e i t i s e s t i m a t e d t h a t one m i l l i o n worke r s s u f f e r f rom s e r i o u s h e a r i n g l o s s . Th i s f i g u r e seems to be a s e r i o u s u n d e r e s t i m a t e as Bragdon (1968) quotes e s t i -mates from': 1 . Amer i can Mutua l I n su rance A l l i a n c e . Between f i v e and s i x m i l l i o n worker s have a h e a r i n g i m p a i r m e n t . 2. Dr. Aram G l o r i g . S i x m i l l i o n men have work c o n d i t i o n s w i t h a p o t e n t i a l to damage h e a r i n g . 3. P u b l i c H e a l t h S e r v i c e . S i x and a h a l f m i l l i o n peop le have impa i red h e a r i n g . 4. Save Your Hea r i n g F o u n d a t i o n . F i f t e e n m i l l i o n peop le have a h e a r i n g d i s a b i l i t y . The Ma s s a chu se t t s Audubon S o c i e t y (1968) quotes s t u d i e s done a t C o l g a t e U n i v e r s i t y wh ich show t h a t the average worke r spends o n e - f i f t h of h i s energy f i g h t i n g n o i s e . No i s e causes a l o s s of nervous energy wh ich i n t u r n l e ad s to the d e t r i m e n t , i n h e a l t h and w e l f a r e of the i n d i v i d u a l ( S e n e n k e r S p r u n g l i i , 1967 ) . Cook and Haverbeke (1969) s t a t e t h a t the mere p re sence of n o i s e causes an i n a b i l i t y to- c o n c e n t r a t e and- a d i s t u r b a n c e , of r e s t and s l e e p wh ich i n t u r n g i v e r i s e to o t h e r f r u s t r a -t i o n s . • • One o f the major works on the n o n - a u d i t o r y e f f e c t s of n o i s e i s t h a t of C a r p e n t e r ( 1962 ) . He d i v i d e s the e f f e c t s i n t o t h r e e s u b - g r o u p s , namely -1. I n t e r f e r e n c e w i t h speech c o m m u n i c a t i o n . 2. Harm to an i n d i v i d u a l ' s h e a l t h and temper . 3. Harm to pe r fo rmance a t work or p l a y . 2 .3.2 P h y s i c a l . The a c t u a l p h y s i c a l e f f e c t s of n o i s e on man are few but t he se few b r i n g about a wide v a r i e t y of s econda ry p h y s i o l o g i c a l and p s y c h o l o g i c a l r e s p o n s e s . . One r e p o r t e d , p h y s i c a l e f f e c t o f n o i s e t h a t does not d i r e c t l y a f f e c t man has been the damage caused to w i l d e r n e s s a reas by s o n i c booms. Welch (1 968) r e p o r t s ' t w o cases where a s o n i c boom has l o o s ened rock.. The f i r s t f a l l has cove red an- a n c i e n t I n d i a n c l i f f d w e l l i n g , the second d e s t r o y e d a un ique s and -s tone f o r m a t i on . R e t u r n i n g to the e f f e c t of n o i s e on man, t h e r e i s o n l y one major r e c e p t i v e organ to the p h y s i c a l s t i m u l u s of n o i s e , and t h a t i s the e a r . K r y t e r (1950) quotes work done by P a r r a c k et_. aj_. who found the f o l l o w i n g p h y s i c a l e f f e c t s on men exposed to a 150 d e c i b e l . n o i s e : 1. A h e a t i n g of the s k i n . 2. At c e r t a i n low f r e q u e n c i e s a v i b r a t i o n of the c r a n i a l bones , a i r movement i n the • na sa l passages and s i n u s e s and a b l u r r i n g o f v i s i o n p resumab ly caused by a v i b r a t i o n of the e y e b a l I s . 3. An appa ren t weaken ing of the body s u p p o r t i n g m u s c u l a t u r e . The most obv i ou s p h y s i c a l e f f e c t of n o i s e on man i s t he r u p t u r i n g of the eardrum. At l ower sound p r e s s u r e l e v e l s i t i s the p h y s i c a l s t i m u l u s of chang ing p r e s s u r e l e v e l s on the eardrum t h a t causes c e r t a i n p h y s i o l o g i c a l a n d . p s y c h o l o g i c a l r e s p o n s e s . 2 .3 .3 Phys i o l o g i c a l . S c h a f e r (1969) r e p o r t e d some f i n d i n g s of the U n i t e d S t a t e s o f Amer i ca N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r a t i o n to the e f f e c t t h a t peop le wo r k i n g around r o c k e t ' l a unch i n g pads s u f f e r f rom nausea and e p i l e p t i c f i t s . Wh i l e g i v i n g n o t i c e of a symposium to be h e l d on the p h y s i o l o g i c a l e f f e c t s on a u d i b l e s o u n d , W e l c h (1969) notes t h a t : . .' . through its a c t i v a t i n g effect upon the subcortical neuronal systems of the brain, sound, either continuous or intermittent, modifies the pacing by the brain.of cardio- -vascular, endocrine, metabolic, reproductive, and neurological function. • The M a s s a c h u s e t t s Audubon S o c i e t y s t a t e d t h a t n o i s e r a i s e s b l ood p r e s s u r e , and s t a r t s a i l m e n t s such as a l l e r g i e s and u l c e r s . S a t a l o f f and Zap.p (1 965 ) g i v e a d e s c r i p t i o n of the e f f e c t of e n v i r o n m e n t a l n o i s e on the i n n e r ear.: . . . sound induced motion of the f l u i d in the cochlea induces shearing and bending movements of .the hair c e l l s in the organ of c o r t i , which, in turn result in e l e c t r i c a l stimuli transmitted by the auditory nerve. Prolonged and excessive noise eventually produces- d e t e r i o r a t i o n and., f i n a l l y destruction of hair c e l l s , and thus disrupts the sound transmission mechanism. C a r p e n t e r (1962) r e p o r t s t h a t on the on se t of a l o ud u n f a m i l i a r n o i s e t h e r e e x i s t s a t r a n s i e n t i n c r e a s e i n m u s c u l a r t e n s i o n , of h e a r t and r e s p i r a t i o n r a t e s , and a t r a n s i e n t change i n e l e c t r i c a l s k i n r e s i s t a n c e . A more permanent , or l o n g e r l a s t i n g e f f e c t i s s a i d to be the c o n t r a c t i o n of the a r t e r i o l e s of the hand. 2 .3 .4 P s y c h o l o g i c a l . S ' chafer (1969) d i scuss .es work done, a t the Max. P l ank I n s t i t u t e i n West Germany to d i s c o v e r why i r o n f o u n d r y worke r s have more e m o t i o n a l and f a m i l y problems than peop le who work i n q u i e t e r e n v i r o n m e n t s . C a r p e n t e r (1962) h y p o t h e s i s e s t h a t n o i s e exposu re i n c r e a s e s the p r o b a b i l i t y of an i n d i v i d u a l p r o d u c i n g symp-toms of any n e u r o s i s to which he i s p r e d i s p o s e d . To some e x t e n t he d e s t r o y s h i s own h y p o t h e s i s by r e p o r t i n g some n e g a t i v e t e s t s made upon U n i t e d S t a t e s nava l p e r s o n n e l s e r v i n g on a i r c r a f t c a r r i e r s . What i s perhaps be s t c a t e g o r i s e d as a p s y c h o l o g i c a l e f f e c t of n o i s e i s c i t e d by Ho rn i g ( 1 9 6 8 ) , when he d i s c u s s e s the l o s s i n p r o p e r t y v a l u e s i n a r ea s ' of h i gh n o i s e i n t e n s i t y . Th i s r e p o r t , i n d i s c u s s i n g the p s y c h o l o g i c a l s t r e s s e s i nduced by n o i s e , uses the example of the embarassment caused by the n o i s e g e n e r a t e d w h i l s t u s i n g bathroom f a c i l -i t i e s . Sug/ihara and K i tayama (1 966) comment on the nerve s t r e s s caused by s o - c a l l e d " a t t a c k n o i s e s " i n the wood work ing• i n d u s t r i e s . In war t ime sound has been used as a weapon. Examples a re found i n the n o i s e g ene r a t ed by a s t u k a d i vebombe r , or i n the ' g l o c k e n s p i e l " t a c t i c of the G e s t a p o , when a bucke t p l a c e d over the p r i s o n e r ' s head i s . c o n t i n u o u s l y b e a t e n . 2.4 How Can No i se Be A t t e n u a t e d ? 2 2.4.1 I n ve r s e square l aw. The i n f o r m a t i o n f o r t h i s an a r t i c l e e n t i t l e d ' " P r o p a g a t i o n 1962 ) . s e c t i o n was of Sound i n o b t a i n e d f rom A i r " (Pa r k i n , An. i m a g i n a r y sound source suspended i n space em i t s sound energy . Three d i m e n s i o n a l l y t h i s sound, energy w i l l sp read out i n ever w i d e n i n g s p h e r e s . As the d i s t a n c e f rom the s ou r ce i n c r e a s e s the sound energy per u n i t a r e a ' d e c r e a s e s . Th i s r e l a t i o n s h i p i s a p r o p o r t i o n a l one, the sound' p r e s s u r e or energy d e c r e a s i n g p r o p o r t i o n a l l y to the square of the d i s t a n c e from the s o u r c e . Th i s i s known as the i n v e r s e square law and i t a p p l i e s to a l l e n e r g i e s and f r e q u e n c i e s of sound. The p i c t u r e i s s i m i l a r when a d i r e c t i o n a l s ou r ce of sound i s c o n s i d e r e d . 2.4.2 A i r A b s o r p t i o n . The a b s o r p t i o n of sound by a i r i s a f u n c t i o n of the r e l a t i v e h u m i d i t y and t empe ra tu re of the a i r . These two f a c t o r s w i l l be c o n s i d e r e d s e p a r a t e l y l a t e r i n t h i s s e c t i o n . At the moment s u f f i c e i t to say t h a t the a b s o r p t i o n i s a f u n c t i o n of the amount of a i r the sound passes t h r o u g h . I t i s t h e r e f o r e e xp re s sed as so many d e c i b e l s per thousand f e e t . Th i s a b s o r p t i o n i s n e g l i g i b l e a t f r e q u e n c i e s below 1000 c y c l e s per s e c o n d , but has a c o n s i d e r a b l e e f f e c t i n t h e - h i g h e r f r e q u e n c i e s . . 2 .4 .3 Ground r e f l e c t i o n . . There e x i s t two paths f o r a sound to t r a v e l f rom i t s s ou r ce ' A ' to a r e c e i v e r * B ' . The f i r s t path i s d i r e c t and s t r a i g h t . The second path i s a r e f l e c t e d one , the sound h i t t i n g the ground and bounc ing up to the r e c e i v e r . The n a t u r e and e x t e n t of t h i s r e f l e c t i o n w i l l depend on the n a t u r e and topography of the g round . The ground i s s o f t and ab s o r ben t then the sound p r e s s u r e l e v e l at ' B ' w i l l be l e s s than i f the ground was hard and r e f l e c t i n g . F u r t h e r e f f e c t s o c c u r when the two waves a r r i v e d i r e c t l y i n phase or i n o p p o s i t e phase. The f o rmer w i l l a lmos t doub le the sound p r e s s u r e l e v e l , the l a t t e r a lmos t h a l f i t . For s h o r t d i s t a n c e s between ' A ' and ' B ' the e f f e c t i s smal l * but d i f f e r e n t c o n d i t i o n s are found when ' A ' and ' B ' a re s e p a r a t e d by hundredso r thousands of f e e t . 2.4.4 C I i m a t o l o g i c a l e f f e c t s . Wiener and Keast (1959) l i s t t e m p e r a t u r e , wind speed and d i r e c t i o n and h u m i d i t y as among the most i m p o r t a n t f a c -t o r s a f f e c t i n g the p r o p a g a t i o n of sound. They a l s o l i s t t u rbu1ance as an a d d i t i o n a l a t t e n u a t i n g f a c t o r . E y e r i n g (1946) measured t e m p e r a t u r e , wind v e l o c i t y and r e l a t i v e h u m i d i t y d u r i n g h i s e x p e r i m e n t s on j u n g l e a c o u s t i c s . Embleton (1963) measured wind v e l o c i t y and t e m p e r a t u r e . Each of the above ment ioned f a c t o r s t o g e t h e r w i t h tho se of f o g and snow w i l l now be b r i e f l y c o n s i d e r e d . 1. Temperature - The v e l o c i t y of sound i n c r e a s e s w i t h a r i s e i n the a i r t e m p e r a t u r e . U s u a l l y d u r i n g day t ime the t e m p e r a t u r e o f the a i r i s g r ea te r - near to the ground than i t i s i n the h i g h e r l a y e r s . T h i s causes the sound waves h i g h e r above the ground to t r a v e l s l owe r than those near the g round . The net e f f e c t i s a bend ing of the waves up-ward and a r e d u c t i o n i n the sound p r e s s u r e l e v e l . The conve r s e i s t r u e at n i g h t when the t empe ra tu re i s c o o l e r near to the ground t h a n - i t i s i n the upper l a y e r s . 2. R e l a t i v e Hum id i t y - Stephens and Bate (1966) r e p o r t on work done by Knudsen i n the n i n e t e e n t h i r t i e s to show the e f f e c t of h u m i d i t y on the a b s o r p t i o n of sound i n a i r . Knudsen found a c r i t i c a l value- f o r maximum a b s o r p t i o n , but t h i s v a l u e v a r i e s a c c o r d i n g to the f r e q u e n c y . S tephens and Bate go on to quote work done by Evans and B a x l e y at . the N a t i o n a l P h y s i c s L a b o r a t o r y . Evans and B a x l e y ' s f i g u r e s are d i s t r i b u t e d such t h a t maximum a b s o r p t i o n o c cu r s a t 5% r e l a t i v e h u m i d i t y a t a f r e q u e n c y of 1,000 c y c l e s per second r i s i n g to 20% r e l a t i v e h u m i d i t y a t 12,500 c y c l e s per s e c o n d . The a t t e n u a t i o n i s sma l l and r a p i d l y f a l l s o f f a f t e r t he se peaks to an a lmos t c o n s t a n t l e v e l up to 100% r e l a t i v e hu-m i d i t y . 3. Wind - Wind a c t s on sound i n a manner not too d i f f e r e n t l y to t h a t e x h i b i t e d by t e m p e r a t u r e . I f a wind i s b l o w i n g t h e r e i s a lways a wind g r a d i e n t , i . e . the wind near the ground i s not moving as f a s t as the wind h i g h e r up. When the r e c e i v e r i s s t a n d i n g upwind t h i s means t h a t th e sound waves n e a r e s t the ground w i l l be t r a v e l l i n g the f a s t e s t . Th i s w i l l cause a bend ing upward o f the sound waves and a net d e c r e a s e of the sound p r e s s u r e 1eve l . C o n v e r s e l y downwind the waves w i l l be bent downward c a u s i n g a net i n c r e a s e i n the sound p r e s s u r e l e v e l . O b v i o u s l y a t r i g h t ang l e s to the wind t h e r e s hou ld be no e f f e c t . 4. T u r b u l e n c e - T u r b u l e n c e i n the atmosphere has o n l y a s m a l l e f f e c t on the p r o p a g a t i o n of sound. I t can cause minor f l u c t u a t i o n s a t the r e c e i v i n g p o i n t and can cause a s c a t t e r i n g of the sound energy i n t o a reas t h a t would o t h e r w i s e have l i t t l e ene r gy . 5. Fog and Snow - Fog causes an e x t r a a b s o r p t i o n to t a ke p l a c e i n the a i r . The amount of t h i s e x t r a a t t e n u -a t i o n depends on the f r e q u e n c y . Dayt ime fogs are o f t e n a s s o c i a t e d w i t h ' f r e a k ' t empe ra t u r e g r a d i e n t s wh ich can c r e a t e a s k i p p i n g e f f e c t and r e s u l t i n abnormal r e c e p t i o n s . Snow on the ground forms an ab s o r ben t l a y e r and as such g r e a t l y a f f e c t s the r e f l e c t e d wave. B o n v a l l e t (1951) found a 2 d e c i b e l drop i n the 400 to 800 c y c l e s per second f r e q u e n c y range w i t h a b l a n k e t of snow on the g round . The a t t e n u a t i o n was g r e a t e r a t h i g h e r f r e q u e n c i e s and s m a l l e r a t l o w e r ones . 2 .4 .5 At the s o u r c e . The method of n o i s e c o n t r o l a t the s ou r ce c o n s i s t s of e n c l o s i n g the n o i s e s ou r ce i n a sound p r o o f box , or so m o d i f y i n g the sou rce such t h a t i t p roduces l e s s n o i s e . The obv iou s example i s the a d d i t i o n of m u f f l e r s to the exau s t systems of a u t o m o b i l e s . In c e r t a i n case.s t h e r e i s a' good argument to d e c r e a s e s t i l l f u r t h e r the exhau s t n o i s e . There i s , however, a happy medium below wh ich l e v e l t he c a r s would be so q u i e t as to g r e a t l y i n c r e a s e the r i s k o f p e d e s t r i a n a c c i d e n t s ( R o b i n s o n , 1962) . The same p r i n c i p l e of c o n t r o l a p p l i e s to i n d u s t r i a l n o i s e . In t h i s ' s i t u a t i o n peop le had a more t o l e r a n t a t t i -tude towards n o i s e . B u r r i s (1962) makes t h i s p o i n t when he s t a t e s : . . . 'getting the thing to, run ' was of more importance than the c l a t t e r and bang coming from.the new production machines which had been developed. S i l e n c i n g was weighed against the d o l l a r s it would take from the t i l l and came out second best. That s i l e n c i n g at the sou rce i s p o s s i b l e has been demons t r a ted many t i m e s . An th rop (1969) r e p o r t s two B r i t i s h i n n o v a t i o n s wh ich produced a m u f f l e d a i r compres so r and a q u i e t e n e d jack -hammer . U n f o r t u n a t e l y , i n many c a s e s , a r e d u c t i o n i n n o i s e means a r e d u c t i o n i n p r o d u c t i o n . 2.4.6 At the l i s t e n e r . B a s i c a l l y t he se e x i s t two ways of r e d u c i n g n o i s e a t the l i s t e n e r . The f i r s t method i n v o l v e s the use of ear p l u g s . The se , however , are f r e q u e n t l y u n c o m f o r t a b l e and d i f f i c u l t i e s a re e x p e r i e n c e d pe r suad ing , peop le to use .'them. The second method i n v o l v e s the c o n s t r u c t i o n of a sound p r o o f box i n w h i c h an o p e r a t o r , who would o t h e r w i s e be exposed to h i gh n o i s e l e v e l s , i s s i t u a t e d . T h i s approach has been a d o p t e d , on o c c a s i o n s , i n the woodworking i n d u s t r y . 2 .4.7 By c o n t r o l l i n g the d i r e c t i o n . Th i s method of c o n t r o l a c c e p t s t h e n o i s e f rom the s ou r ce and t r y s t o f i n d a way of d i r e c t i n g the n o i s e away f rom p o t e n t i a l r e c e i v e r s . T h i s method i s not as easy as i t seems, becau se , as was shown e a r l i e r , of the h i gh d i f -f r a c t i o n of sound. N e v e r t h e l e s s some form of s u cce s s i s a c h i e v e d by d i r e c t i n g n o i s e skywards by some k i n d of m e c h a n i c a l d e v i c e ( R o b i n s o n , 1962) . Ano the r a s p e c t of t h i s t ype of c o n t r o l i s found i n the r e g u l a t i o n s wh ich govern f l y i n g ( S c h e n k e r - S p r u n g l i i , 1967 ) . However, the U n i v e r s i t y of Ch i cago Law Review (1968) m a i n t a i n s t h a t : . . . The ( C i v i l Aeronautics) Board has • u t t e r l y disregarded environmental impact, a- major ex-ternal cost of a i r transportation. With the i n t r o d u c t i o n of commerc ia l s u p e r s o n i c t r a v e l t i g h t e r r e g u l a t i o n s g o v e r n i n g f l i g h t paths w i l l s u r e l y f o l l o w . Anderson (1969) r e f e r r i n g to work done i n Germany, p o i n t e d out the r e d u c t i o n i n sound p r e s s u r e l e v e l caused by a 100 f o o t wide c u t t i n g i n a f o r e s t near an a i r p o r t . Sound t r a v e l l i n g t h rough the c o l d e r a i r of the f o r e s t - , h i t s the p a r t i a l vacuum c r e a t e d by the c o n v e c t i o n c u r r e n t s i n the warmer c u t t i n g , and moves upwards. Anderson i s i n the p r oce s s of a p p l y i n g t h i s p r i n c i p l e to r o a d s i d e p l a n t -i ng i n Mary 1 and . 2 .4 .8 By the use of b a r r i e r s . Rob in son (1962) recommends the use o f an i n t e r v e n i n g sound a b s o r b i n g b a r r i e r , s hou l d i t be i m p o s s i b l e or d i f f i -c u l t to c o n t r o l the n o i s e a t the s ou r ce or at the l i s t e n e r . Sometimes t he se s c r e e n s may a c t as f i l t e r s , s c r e e n i n g out c e r t a i n u n d e s i r e d f r e q u e n c i e s . Some i l l u s t r a t i o n o f t h i s method i s g i v e n by S c h e n k e r - S p r u n g l i i (1967) when he uses the examples of sound p r o o f hangars f o r eng ine t e s t i n g , and the hou seho ld use of sound a b s o r b i n g m a t e r i a l s such as drapes., c u r t a i n s , and c a r p e t s . Th i s t h e s i s i s conce rned w i t h the use of n a t u r a l or a r t i f i c i a l l y c r e a t e d b a r r i e r s of t r e e s to a t t e n u a t e sound. Perhaps the f i r s t work done i n t h i s f i e l d was t h a t by E y e r i n g (1946) i n the j u n g l e s o f Panama. Work ing i n s t and s o f n a t u r a l t r o p i c a l f o r e s t he f o u n d : ... the t e r r a i n loss c o e f f i c i e n t s , measured in decibels -per foot, were measured for various types of jungle and were found to be a function of the frequency and of the density of the . t e r r a i n , the density of the t e r r a i n being measured by the d i f f i c u l t y of penetration and the. distance a foreign object may be seen. The g r a p h i c a l r e p r e s e n t a t i o n of E y e r i n g ' s r e s u l t s a re d e p i c t e d i n F i g u r e 1. 111 W W V W 7 / / / T \ \ \ \ S \Wi VWYVW F I G . 1. A chart from which to estimate terrain loss coefficients for tropical jungles. Zone 1, very leafy, one sees a distance of approximately 20 ft., penetration by cutting; zone 2, very leafy, one sees approximately 50 ft., penetrated with difficulty but without cutting; zone 3, leafy, one sees a distance of approximately 100 ft., free walking if care is taken; zone 4, leafy, one sees a distance "of approximately 200ft., penetration is rather easy; zone 5, little leafy undergrowth, large bracketed trunks, one sees a ^'distance of approximately 300 ft., penetration is easy. ( A f t e r E y e r i n g , 1946) E y e r i n g ' s v a l u e s g i v e t o t a l a t t e n u a t i o n s a t 100 f e e t a s d e p i c t e d i n T a b l e 6. A t t e n u a t i o n s a t 100 Feet Ob ta i ned From E y e r i n g ' s R e s u l t s Zone F requency A t t e n u a t i o n i n D e c i b e l s 1 1000 7.5 1 5000 15.0 2 1000 6.0 2 5000 11.0 3 1000 4.0 3 5000 8.5 4 1000 2.5 4 5000 6.0 5 1000 4.5 5 5000 6.5 Wiener and Keast (1959) d i d some work i n dense e v e r g r e e n f o r e s t s of e a s t e r n Ma ine . As p a r t of a l a r g e r s t u d y , they i n v e s t i g a t e d sound a t t e n u a t i o n , at d i s t a n c e s up to 800 f e e t , th rough b e l t s of t r e e s . The g r a p h i c a l r e p r e s e n t a t i o n of t h e i r r e s u l t s i s r ep roduced i n F i g u r e 2. They m a i n t a i n t h a t the a t t e n u a t i o n c o e f f i c i e n t ob-t a i n e d by E y e r i n g , i n j u n g l e s of comparab le d e n s i t y , i s not. g r e a t l y d i f f e r e n t f rom t h e i r own. 20 S i 5-10 FT R = 3 FT . . TREE HEIGHT ± 20 -10FT AVG. VISIBILITY 70FT •f//i 1/3 OCTAVE BAN OS • OCTAVE SANDS '/, ' / a/" /A Ml' $,!//"" •//)"'[ 200 1000 10000 CENTER FREOUENCY OF BANO IN CYCLES PER SECOND F I G . 2. Excess attenuation coefficients determined in dense •evergreen woods, for sound propagated along the ground. This is exclusive of attenuation due to inverse square law and molecular absorption. ( A f t e r Wiener and K e a s t , 1959) The v i s i b i 1 i t y o f a l l o f Wiener and ' K e a s t ' s s t ands was 70 f e e t , wh ich app rox ima te s w i t h e i t h e r zone 1 or zone 2 of E y e r i n g ' s r e s u l t s . The a t t e n u a t i o n s a re compared i n T a b l e 7. i TABLE 7 Compar i son of the R e s u l t s of E y e r i n g w i t h Those o f Wiener and Keast F requency Ey e r i n g Di s t ance Wiener & Keast Di s t a n ce 1000 C .P . S . 6.0 DB. 50 f e e t 2.5 DB. 70 f e e t 5000 C .P . S . 11.0 CB. 50 f e e t 7.0 DB. 70 f e e t 1000 C .P . S . 4.0 DB. 100 f e e t 2.5 DB. 70 f e e t 5000 C .P . S . 8.5 DB. 100 f e e t 7.0 DB. 70 f e e t Hess and K u r s t e i n e r (1961) r e p o r t the r e s u l t s ob-t a i n e d by M e i s t e r i n 1959. These a re r e p e a t e d i n T a b l e 8 ( A t t e n u a t i o n s i n d e c i b e l s per m e t r e ) . TABLE 8 A t t e n u a t i o n s Ob ta i ned by M e i s t e r i n 1959 f o r V a r i o u s V e g e t a t i o n Types Wood Type F requency Band A v . - a l 1 Freqs . P i ne Crown 200-400 400-800 800-1600 1600-3 200 3200-6400 .15 .08- . 11 . 13 - .15 • . 14- .15 • .16 .19- .20 P i n e Nu r se r y .10-.11 .10 .10 - .15 .16 .14 - .20 .15 Spruce Crown .10 - .12 . 14 - . 17 .18 .14 - .17 .23 - .30 .18 Dense Dec i d . Copp i ce .05 .05 - .07 .08 - .10 . 1 1 - . 15 . 1 7 - . 20 .12 - .17 Dense Bushes . 13 - . 15 .17 - .25 . 18 - .35 .20- .40 .30 - .50 . 25 - .35 [ A f t e r Hess and K u r s t e i n e r (.1961)] Hess and K u r s t e i n e r go o n t o r e p o r t on some f i n d i n g s o f t h e i r own.. U n f o r t u n a t e l y the i r . re s u 1 t s a re g i v e n i n d e c i b e l s measu red , i n s t e a d o f a t t e n u a t i o n c o e f f i c i e n t s or d e c i b e l s a t t e n u a t e d . R e g a r d l e s s of t h i s f a c t the shape of t h e i r c u r ve of d e c i b e l s measured ve r su s f r e q u e n c y i s o f some i n t e r e s t and i s r e p e a t e d i n F i g u r e 3. 150 300 600 1200 2400 4800 lOks FIGURE 3. FREQUENCY ANALYSIS OF THE SOUND OF A MAGIRUS-DGUTZ-DIESEL AT THE 100 METRE SOUND LOCATION 1 . Located in an open f i e l d . 2 . High growth form trees. • _ 3. High growth form trees with an under storey. 4 . Low growth form trees with an understorey. ( A f t e r Hess and K u r s t e i n e r , 1961) A t t e n u a t i o n i s o b t a i n e d by s u b t r a c t i n g the v a l u e s o f c u r ve s 2 to 4 f rom those of cu r ve 1. Compar i son w i t h e i t h e r E y e r i n g or Wiener and K e a s t ' s r e s u l t s i s d i f f i c u l t because of the ve r y g e n e r a l d e s c r i p t i o n s of s t and t y p e . Embleton and T h i e s s e n (1962) w h i l s t i n v e s t i g a t i n g the e f f e c t o f t r a i n n o i s e s and the use of a d j a c e n t l a n d , d i s c o v e r e d one o r two i n t e r e s t i n g f a c t s . They found a 15 to 25 DB. a t t e n u a t i o n a t 1000 f e e t , the a c t u a l amount depend ing upon the d e n s i t y o f the unde r g r owth . They a l s o s t a t e t h a t s tands w i t h c l e a r bo l e s to a h e i g h t of 6 to 8 f e e t spaced about 10 f e e t a p a r t showed no a t t e n u a t i o n . Of perhaps the g r e a t e s t i n t e r e s t i s t h a t the a t t e n u -a t i o n i n the 600-1200 C.P .S . band was l e s s than t h a t i n the 300-600 C.P .S . band. Th i s phenomenon was f i r s t r e p o r t e d by E y e r i n g who a t t r i b u t e d i t to an e x p e r i m e n t a l e r r o r . Embleton and T h i e s s e n ' s r e s u l t s show a d i p which cannot be accoun ted f o r by e x p e r i m e n t a l e r r o r a l o n e . In an a t tempt to i n v e s t i g a t e t h i s phenomenon i n p a r t i c u l a r , and the a t t e n u a t i o n of sound by t r e e s tands i n g e n e r a l , Embleton (1963) per fo rmed a whole new s e r i e s o f e x p e r i m e n t s . He found the d i p aga i n most pronounced ( see F i g u r e s 4 and 5 ) . Embleton h y p o t h e s i s e d t h a t t h i s d i p was caused by a r e s o n a t i n g e f f e c t o f the t r ee s ' a t t h i s p a r t i c u l a r f r e q u e n c y . To t e s t t h i s h y p o t h e s i s he a t t a c h e d a c c e l e r o m e t e r s to . v a r i o u s p a r t s o f the t r e e s . The r e s u l t s o f the t e s t a re rep roduced i n F i g u r e 6. J—1 100 COO IOOOO FREQUENCY - cp» F I G . 4 . Excess attenuation vs frequency, average of all four species of trees; (a) all results, including anomalous "edge effects," and (b) only those results calculated by the conventional method. C E D A R P I N E - l - K L i -C CO Tl -H. ' i—t-i-H !—i--H © C O oco FREQUENCY-cps tt 111 0 - 5 0 F T F R O M S O U R C E 5 0 -1 0 0 F T 1 0 0 -1 5 0 F T 1 5 0 -2 0 0 F T i — * - H J i—iH-H O" CO . O00 "JO -4c r A L L T R E E S - i - i J 1-l-ic.5. Excess attenuation vs frequency. Results broken down by species of trees (vertical columns) and by distances from source (horizontal rows). The last column is the average of the previous four and illustrates the relative effects of distance without regard to species. ' TRUNK RESONANCES 5 20 < 15-w 10-I I o co o o o o o o • o o C 6 a a #) O a a o o • • O o a o o a o o o o a ^ a « a a C O CO O a O . o O a C o o o c C O 400 600' 800 1000 FREQUENCY-cps 2000 F I G . 6- Resonances detected by an accelerometer mounted on several branches of a red pine, plotted as a function of frequency and height of branch. Ease of excitation is indicated by size of mark. Resonances in the trunk detected at a height of 10 ft are shown as a spectrum at the top of figure. ( A f t e r E m b l e t o n , 1963) However, as Embleton puts i t : . . .the s i m i l a r i t y (between t h e o r e t i c a l and measured r e s u l t s ) extends only to the general shape of the curve and its frequency depen-dance; the magnitude predicted by this theory is smaller than the measured effect by a fac-•• tor. of roughly 1000. . . .One may speculate that resonant absorption is s t i l l the primary mechanism', but that some unsuspected feature leads to a magnification of the effect; a l t e r -n a t i v e l y the explanation may need to be based on a t o t a l l y d i f f e r e n t process. Embleton a l s o t r i e d to e s t a b l i s h a r e l a t i o n s h i p between o p t i c a l v i s i b i l i t y and exces s a t t e n u a t i o n . H i s r e s u l t s ( see F i g u r e 7) would seem to d i s a g r e e w i t h those o f both E y e r i n g and Wiener and K e a s t . 60 40 50 OPTICAL VISIBILITY - ft PlC 7." K.yccss att.cnuation/100 ft vs optical visibility. .•There is a lack of any obvious correlation. ( A f t e r Emb le t on , 1963) Swieboda (1965) r e p o r t s the f i n d i n g s of a s t udy done by the P o l i s h I n s t i t u t e of P l a n n i n g and A r c h i t e c t u r e Th i s s tudy showed t h a t s t r e e t p l a n t i n g l owered sound pres-su re l e v e l s by r e d u c i n g the r e f l e c t i o n from b u i l d i n g s and ground s u r f a c e s . Swieboda summarises the r e s u l t s as f o l l o w s : ... small boulevards and loosely placed planting groups within housing developments reduce noise by 4-7 DB. A double row of linden trees, approx-imately 8 metres high lowers the l e v e l , in the summer, on a busy street, by 9 DB. A planting• s t r i p 30 metres wide with loosely placed trees cuts noise by 8-11 DB. Well developed trees and shrubs, with dense f o l i a g e , in a 40 metres wide • s t r i p reduce the average level by 17 DB. and the maximum level by 23 DB. Of perhaps more i n t e r e s t i s the work of Sadowski et,. al_. .which Swieboda a l s o r e f e r s t o . Th i s work compared the a t t e n u a t i n g a b i l i t i e s of b e l t s of d i f f e r e n t t r e e s and the r e s u l t s are r ep roduced be low: TABLE 9 A t t e n u a t i o n s Produced by D i f f e r e n t S p e c i e s Type of P l a n t i n g Width S o u r c e ' No i se R e d u c t i o n i n DB Frequency i n HZ. Hed-ge - w i l d b l a c k l i l a c 1 .8M Truck 250 500 1000 3 4 6 Young l i n d e n t r e e s - s h r u b s between 20 . OM Truck 13 17 23 Young b i r c h e s and A l d e r 20. OM Truck 14 16 21 Dense t r e e s p l u s shrubs 1-1 . 5 M 150 .OM Truck 18 21 23 [ A f t e r Swieboda (1 965 ) ] • R o b i n e t t e (1969) c i t e s numerous examples of a t t e n u -a t i o n of sound by p l a n t s . His r e s u l t s are somewhat hard to i n t e r p r e t due to the appa ren t absence of a c o n t r o l . He s t a t e s t h a t most e f f e c t i v e , - a t t e n u a t i o n i s a c h i e v e d by a p l a n t i n g o f t r e e s and shrubs 25 to 35 f e e t i n w i d t h , low near to the sound s ou r ce and h i g h e r n e a r e r the l i s t e n e r . Cook and Haverbecke (1969) r e p o r t t h a t they w i l l be c o n d u c t i n g a s tudy f o r the U n i t e d S t a t e s F o r e s t S e r v i c e to a s c e r t a i n the a t t e n u a t i n g a b i l i t i e s of t r ee s , and.-shrubs but have as y e t , not r e p o r t e d any r e s u l t s . Chapte r I I I D I S C U S S I O N OF P R O C E D U R E S 3 .1 T h e o r i e s and Hypotheses As was d i s c u s s e d i n the p r e v i o u s c h a p t e r the a t t e n u -a t i o n of sound i s dependent on a number of f a c t o r s , namely: 1. The i n v e r s e square law. 2. A i r a b s o r p t i o n . 3. Ground r e f l e c t i o n . 4. C l i m a t e ( t e m p e r a t u r e , r e l a t i v e h u m i d i t y , w i n d , t u r b u l e n c e , and f o g and snow). 5. R e d u c t i o n a t the s o u r c e . ' 6. R e d u c t i o n a t the l i s t e n e r . 7. C o n t r o l o f the sounds ' d i r e c t i o n . 8. I n t e r v e n i n g b a r r i e r s . 9. .Frequency and i n t e n s i t y o f the sound. In o r d e r to s tudy the e f f e c t of one of t he se f a c t o r s on the a t t e n u a t i o n of sound , the o t h e r f a c t o r s must a l l be s t a n d a r d i z e d or t h e i r e f f e c t s e l i m i n a t e d . T h i s s t udy i s c once rned w i t h the use of an i n t e r v e n i n g b a r r i e r of t r e e s to a t t e n u a t e s ound , and , to a l e s s e r d e g r e e , w i t h how an i n t e r v e n i n g b a r r i e r can be used to c o n t r o l the sounds d i r e c t i o n . The methods used to s t a n d a r d i z e the o t h e r f a c t o r s w i l l be d i s c u s s e d i n the nex t c h a p t e r . The b a s i c t h e o r y beh ind the use of t r e e s as a sound a t t e n u a t i n g b a r r i e r i s t h a t they w i l l d i f f r a c t , absorb and r e f l e c t s u f f i c i e n t sound waves to produce a s i g n i f i c a n t r e d u c t i o n i n the sound p r e s s u r e l e v e l . I t i s h y p o t h e s i s e d t h a t the amount of a t t e n u a t i o n caused by the b a r r i e r w i l l be a f u n c t i o n of the t r e e s p e c i e s i n g e n e r a l and of the . s t a n d c h a r a c t e r i s t i c s o f the s p e c i e s i n p a r t i c u l a r . The e x p e r i m e n t was d e s i g n e d to t e s t the f o l l o w i n g l i s t o f hypothes e s : 1. The sound p r e s s u r e l e v e l r e c o r d e d a t v a r i o u s i n t e r v a l s t h r ough a s c r e e n o f t r e e s w i l l de-• c r e a s e i n p r o p o r t i o n t o the square of the d i s t a n c e from the sound s o u r c e . 2. A t t e n u a t i o n w i l l v a r y w i t h t h e s p e c i e s o f the i n t e r v e n i n g s c r e e n . • 3- A t t e n u a t i o n w i l l - v a r y w i t h the season of the y e a r . 4. A t t e n u a t i o n w i l l v a r y w i t h the b a s a l a r e a , i n terms o f square f e e t per a c r e , o f the i n t e r v e n i n g s c r e e n . 5. A t t e n u a t i o n w i l l v a r y - w i t h the number of stems p e r a c r e i n the i n t e r v e n i n g s c r e e n . 6. A t t e n u a t i o n w i l l v a r y w i t h the h e i g h t a t which the f i r s t b r a n c h o c c u r s on the t r e e . 7- A t t e n u a t i o n w i l l v a r y w i t h the h e i g h t a t . which the f i r s t l i v e b r a n c h o c c u r s on .the t r e e . 8. A t t e n u a t i o n w i l l v a r y w i t h the l e n g t h o f the l i v e crown. 9- A t t e n u a t i o n , w i l l v a r y w i t h the age of the s t a n d . 10. A t t e n u a t i o n w i l l v a r y w i t h the. average d i a m e t e r a t b r e a s t h e i g h t o f the stand". • 12.- A t t e n u a t i o n w i l l v a r y w i t h the f r e q u e n c y o f sound. 3.2 E x p e r i m e n t a l Des ign A . d i a g r a m a t i e r e p r e s e n t a t i o n of the e x p e r i m e n t a l de s i g n i s shown i n F i g u r e 8. 1 . Season The w i n t e r da ta were c o l l e c t e d d u r i n g the month of Feb rua r y 1970 and the summer data d u r i n g the month of June 1970. 2. S p e c i e s Four d i f f e r e n t s p e c i e s or s p e c i e s c o m b i n a t i o n s were s t u d i e d . These were A) Red A l d e r (Alnus rubra Bong) B) Western w h i t e b i r c h {Betula vapyrifera Marsh. Va r . Commutata ( R e g e l ) ] C) D o u g l a s - f i r \_Pseudotsuga menziesii ( M i r b . ) F r anco ] D) Western hemlock [Tsuga heterophylla ( R a f . ) S a r g . ] Western red cedar {Thuja p l i c a t a Donn) Douglas f i r [Pseudotsuga menziesii ( M i r b . ) ; F r anco ] S p e c i e s t y p e D w i l l h e r e a f t e r be known as ' m i x t u r e 1 . 3. Stand F i v e s e p a r a t e s tands were l o c a t e d and measured f o r Red a l d e r and the m i x t u r e . Four s t ands were measured i n the case of Western w h i t e b i r c h and Douglas f i r . Figure 8- Diagramatic representation of the experimental design-NTER SUMMER SPECIES STAND 5 SETTING A SETTING C READING I READING 2 F= Frequency Sound p r e s s u r e l e v e l s were r e c o r d e d a t the three-d i s t a n c e s of 50 f e e t , 100 f e e t , and 150 f e e t f rom the sound .source. 5. F requency The e i g h t s e l e c t e d f r e q u e n c i e s cove r most of the a u d i b l e range of the average human e a r . The e i g h t f r e -quenc i e s were : 1 . . 1 2 5 c y c l e s per. second 2 . 250 c y c l e s per second 3 . 500 c y c l e s per second 4 . 1 0 0 0 c y c l e s per second 5 . 2 0 0 0 c y c l e s per second 6. 4000 c y c l e s per second 7 . 8 0 0 0 c y c l e s p e r second 8 . 1 2 0 0 0 c y c l e s per second 6 . S e t t i n g T h e ' s e t t i n g s a re found on the sound l e v e l meter and r e p r e s e n t a w e i g h t i n g c h a r a c t e r i s t i c of the measured sound p r e s s u r e l e v e l . S e t t i n g ' A ' d i s c r i m i n a t e s h e a v i l y a g a i n s t the low f r e q u e n c y sounds and g i v e s a c l o s e a p p r o x i m a t i o n to s u b j e c t i v e e s t i m a t e s of l o u d n e s s , annoyance and speech i n t e r f e r e n c e . S e t t i n g ' C ' g i v e s a n e a r l y u n i f o r m re sponse ove r the whole f r e q u e n c y r a n g e , g i v i n g a s l i g h t d i s c r i m i n a -t i o n a g a i n s t v e r y low f r e q u e n c i e s . I t g i v e s a good i n d i c a -t i o n of the o v e r a l l sound p r e s s u r e l e v e l . The re sponse of the two s e t t i n g s ove r t h e whole f r e q u e n c y range a re shown i n F i g u r e 9. 20c/s SO 100 200 500 l i y s 2 5 10 20 FREQUENCY Figure T y p i c a l A- , B-, and C -weighted random- inc idence responses of the sound- leve l meter. ( A f t e r Gene ra l R a d i o , 1966) B a s i c a l l y i t means t h a t any g i v e n sound w i l l have a h i g h e r d e c i b e l r e a d i n g on the ' C s e t t i n g a t the l owe r f r e q u e n c i e s and on the ' A ' s e t t i n g a t the h i g h e r f r e q u e n -c i e s . 7. Read ing Two r e a d i n g s were t aken f o r each, s e t t i n g to produce an average v a l u e f o r the measured sound p r e s s u r e l e v e l . I t was hoped by t h i s p r o cedu re to reduce p e r s o n a l e r r o r s made i n r e a d i n g the sound l e v e l m e t e r , and tho se caused by minor f l u c t u a t i o n s i n the ambient sound l e v e l . 3.3 L i m i t a t i o n s The l i m i t a t i o n s of the s tudy a re b a s i c a l l y those a s s o c i a t e d w i t h i t s t i m i n g , i t s l o c a t i o n , and the p r ocedu re a d o p t e d . The e x p e r i m e n t s were o n l y r e p e a t e d t w i c e d u r i n g the cou r se o f a y e a r . The extremes of c l i m a t e were chosen such t h a t i n the w i n t e r the t r e e s tands were i n a dormant c o n d i t i o n , t h e r e be i n g no l e a v e s and l i t t l e u n d e r g r o w t h , and i n the summer the s tands were f u l l y f l u s h e d and l e a f a r ea and undergrowth were at a maximum. The scope o f the e x p e r i m e n t a l r e s u l t s may be l i m i t e d because of t h i s l a c k of cove rage of the. s p r i n g and autumn c o n d i t i o n s . Four t ype s of s t ands were i n v e s t i g a t e d and g r e a t c a r e must be e x e r c i s e d i f the r e s u l t s f rom these s t ands a re t o . b e a p p l i e d to any o t h e r s p e c i e s , or even to the same s p e c i e s i n a d i f f e r e n t l o c a t i o n from the l ower ma i n l and r e g i o n of B r i t i s h C o l u m b i a . In as much as the s tands had to be chosen f rom a l i m i t e d a v a i l a b l e a rea and r e g u l a r age , d e n s i t y and d i a m e t e r g r a d a t i o n s c o u l d not be f o u n d , the n a t u r a l v a r i a b i l i t y of the s tands has tended to c l o u d the r e s u l t s . Three d i s t a n c e s o n l y were measured but as the sound . s ou r ce was l o c a t e d i n the s t a n d , an edge e f f e c t was e l i m i -n a t e d . G r e a t c a re must be t aken i f the r e s u l t s a re to be e x t r a p o l a t e d f o r any d i s t a n c e s g r e a t e r than 150 f e e t . • I t was o r i g i n a l l y i n t e n d e d to a l s o run e x p e r i m e n t s w i t h the sound s ou r ce l o c a t e d o u t s i d e of the t r e e s and measurements made i n the t r e e s and i n open ground on the f a r s i d e of the s t a n d s . Th i s t e c h n i q u e was abandoned f o r two r e a s o n s . F i r s t l y the amount of da ta was i m p o s s i b l e to c o l l e c t i n the t ime a v a i l a b l e , and s e c o n d l y , o n l y a few s tands of s u i t a b l e w i d t h c o u l d be found w i t h open ground on each s i d e . The e i g h t f r e q u e n c i e s cove r the whole a u d i b l e f r e -quency range f o r a h e a l t h y a d u l t male and no d i f f i c u l t y i s e n v i s i o n e d i n e x t r a p o l a t i n g i n f o r m a t i o n f o r any d e s i r e d f r e q u e n c y up to 14,000 c y c l e s per s e cond . The t e c h n i q u e used to a s se s s ground v e g e t a t i o n was a d e f i n i t e l i m i t a t i o n . Th i s v e g e t a t i o n r e p r e s e n t e d , on c e r t a i n o c c a s i o n s , q u i t e a s i z e a b l e p r o p o r t i o n of the b i o -mass of the s t a n d . F u r t h e r , no i n d i c a t i o n of the s l a s h c o u l d be o b t a i n e d , a p a r t f rom a v i s u a l e s t i m a t e , and t h i s may have produced an e r r o r . S u g ge s t i o n s t o overcome the se p r o b l e m s , based on e x p e r i e n c e , a re g i v e n i n Chap te r s VI and V I I I . 3.4 Ana l y s i s I n i t i a l l y a computer programme was c r e a t e d wh ich s e l e c t e d the open ground p l o t t h a t c o r r e sponded c l o s e s t , f rom a c l i m a t i c v i e w p o i n t , w i t h a g i v e n t r e e s t a n d . The programme then s u b t r a c t e d the sound p r e s s u r e l e v e l r e c o r d e d i n the s tand f rom t h a t r e c o r d e d over open g round . However, a subsequent a n a l y s i s of v a r i a n c e on the open ground p l o t s showed no s i g n i f i c a n t d i f f e r e n c e between them. Thus i t was d e c i d e d to o b t a i n a mean v a l u e f o r each f r e q u e n c y , each s e t t i n g , a t each of the t h r e e d i s t a n c e s from a l l the open ground p l o t s , and use t h i s v a l u e to o b t a i n the a t t e n u a t i o n . Th i s v a l u e t o g e t h e r w i t h p e r t i n e n t s tand i n f o r m a t i o n , was punched out on a new computer c a r d . Us ing the se new ca rd s t h r e e s e p a r a t e programmes were s u b s e q u e n t l y r u n . F i r s t l y a s c a t t e r g r a m was p l o t t e d . o f a t t e n u a t i o n a g a i n s t each of the measured s tand v a r i a b l e s , f o r each s p e c i e s and f o r each f r e q u e n c y . Next a r e g r e s -s i o n a n a l y s i s was run i n an a t tempt to d i s c o v e r any r e l a -t i o n s h i p s between a t t e n u a t i o n and c o m b i n a t i o n s of the measured f a c t o r s . F i n a l l y d i f f e r e n c e s , i n a t t e n u a t i n g a b i l i t i e s between the s p e c i e s and f o r the d i f f e r e n t , f r e -quenc i e s were i n v e s t i g a t e d u s i n g the A n a l y s i s o f ' V a r i a n c e programme. Chapte r IV EXPERIMENTAL TECHNIQUES 4.1 Appa ra tu s The f o l l o w i n g i s a comprehens i ve l i s t o f the appa ra tu s used i n a l l s t age s of the s t u d y . 1 . P l o t measurement . .' 1 . F i f t y f o o t , tape 2 . C o l o u r e d marking tape • . 3 - M e t a l Diameter tape • 4 . Hager hypsometer 5 . S i x t e e n i n c h i n c r e m e n t b o r e r 2. Sound sou r c e 1 . M a s t e r tape w i t h e i g h t r e c o r d e d f r e q u e n c i e s 2 . Uher 4000 Report L tape r e c o r d e r . 3- Bogen BT 35A 40 watt power a m p l i f i e r 4 . D e l c o E n e r g i s e r 12 v o l t a u t o m o b i l e b a t t e r y 5 . M a r s l a n d Hawk 2 - 1 2 100 watt l o u d s p e a k e r and c a b i n e t w i t h a s i g h t i n g groove cut a l o n g the top a t r i g h t a n g l e s t o the p l a n e of the s p e a k e r . 3- Sound measurement 1 . G e n e r a l Radio type 1 5 6 5 - A sound l e v e l meter - w i n t e r . 2 . G e n e r a l Radio t y p e 1 5 5 1 - B sound l e v e l meter - summer. 3. W r i s t w a t c h w i t h sweep a c t i o n second hand. 4. C l i m a t e • 1 . S l i n g p s y c hrometer 2 . A l n o r v e l o m e t e r j u n i o r 4.2 P r o cedu re '4.2.1 P l o t measurement. I t was i n i t i a l l y hoped to enumerate the b l o c k s u s i n g t h e v a r i a b l e p l o t t e c h n i q u e . However, due to the v a r i a b l e a reas s amp led , t h i s method was abandoned i n f a v o u r o f a more comp le te enumera t i on l e s s s u s c e p t i b l e to f a c t o r s o u t s i d e the p l o t s . To t h i s end p l o t s were f i r s t d e l i n e a t e d on the ground and the c o r n e r t r e e s marked by t y i n g c o l o u r e d tape around them. For each p l o t t h r e e c o n t i g u o u s b l o c k s , each 30 f t . by 50 f t . were dema r ca t ed , such t h a t the whole • formed a s t r i p 150 f t . by 30 f t . T h i s was done i n the autumn of 1969. Next a 100 per c en t enumera t i on was per fo rmed fo r -each b l o c k . The d i a m e t e r a t b r e a s t h e i g h t was measured f o r each t r e e down to a l i m i t of one i n c h . Below t h i s v a l u e the t r e e s were counted but not measured. The s p e c i e s of t r e e was r e c o r d e d a g a i n s t each measured d i a m e t e r v a l u e . A mean d i a m e t e r v a l u e was now c a l c u l a t e d f o r each 30 f t . by 50 f t . b l o c k . The b a s a l a reas f o r each b l o c k were c a l c u -l a t e d nex t u s i n g the f o l l o w i n g f o r m u l a : Ba sa l A rea = Square Feet where N = number of t r e e s measured D = Average d i a m e t e r at b r e a s t h e i g h t i n i n che s P = P i = 3.1416 The c a l c u l a t e d v a l u e was m u l t i p l i e d by 29.04 to o b t a i n the b a s a l a rea per a c r e f o r one b l o c k . By summat ion, the, b a s a l a reas f o r two and t h r e e c o n t i g u o u s b l o c k s were o b t a i n e d . In stands, where two or more s p e c i e s were p r e s e n t , a s l i g h t l y m o d i f i e d p rocedu re was a d o p t e d . I t was o r i g i n a l l y hoped t h a t i f a mixed s tand was broken down i n t o i t s c o n -s t i t u e n t s , the a n a l y s i s would be a b l e to show the a t t e n u -a t i n g e f f e c t of each s p e c i e s c o n s t i t u e n t . Subsequent a n a l y s i s showed t h i s to be i m p o s s i b l e because of n a t u r a l s t and v a r i a t i o n but the p rocedu re "used to a s c e r t a i n the p e r c e n t a g e c o m p o s i t i o n of a s tand by s p e c i e s i s wor th r e c o r d i n g . F i r s t l y the average d i a m e t e r a t b r e a s t h e i g h t f o r each s p e c i e s i n each b l o c k was c a l c u l a t e d . From t h i s v a l u e the b a s a l a rea per b l o c k , of each s p e c i e s , w a s c a l c u -l a t e d . By summation of the s p e c i e s s u b - t o t a l s the t o t a l , b a s a l a r ea f o r each b l o c k was f o u n d . The ba sa l a rea f o r each s p e c i e s was then d i v i d e d by the ba sa l a rea f o r the b l o c k and m u l t i p l i e d by 100. Th i s gave the pe r cen t age of each s p e c i e s i n each b l o c k . The p r o ce s s was r e p e a t e d f o r eve r y b l o c k i n the s t r i p and the i n d i v i d u a l • b l o c k t o t a l s were summed to g i v e the pe r cen tage c o m p o s i t i o n , by s p e c i e s , f o r two and t h r e e c o n t i g u o u s b l o c k s and hence the comp le te s t r i p . The number of stems per a c r e was found by m u l t i -p l y i n g the t o t a l number of stems counted ( t ho se measured p l u s those too s m a l l to measure) by 29.04 f o r o n e . b l o c k , 14.52 f o r two b l o c k s , and by 9.68 f o r t h r e e b l o c k s . A f t e r the ba sa l a rea and stem enumera t i on was com-p l e t e d ten t r e e s per 150 f o o t s t r i p were sampled to o b t a i n v a l u e s f o r ' the f o l l o w i n g s t and c h a r a c t e r i s t i c s : h e i g h t to the f i r s t l i v e b r a n c h , h e i g h t to the f i r s t b r a n c h , l e n g t h of l i v e c r own , and h e i g h t of the ground v e g e t a t i o n . Trees were s e l e c t e d a t f i f t e e n f o o t i n t e r v a l s t h r oughou t the l e n g t h of s t r i p . At each f i f t e e n f o o t i n t e r v a l the f o l l o w i n g o r d e r of s e l e c t i o n was a d o p t e d . An arm was e l e v a t e d s i deward s u n t i l i t was at r i g h t ang l e s to the body and p a r a l l e l to the g round . At f i f t e e n f e e t : The f i r s t t r e e to appear i n the l i n e of v i s i o n on the l e f t s i d e of the body to the f r o n t o f the e l e v a t e d arm. At t h i r t y f e e t : The f i r s t t r e e to appear i n the l i n e of v i s i o n on the r i g h t s i d e of the body to the f r o n t of the e l e v a t e d arm. At f o r t y - f i v e f e e t : The f i r s t t r e e to appear i n the l i n e of v i s i o n on the r i g h t s i d e of the body to the r e a r of the e l e v a t e d arm. At s i x t y f e e t : The f i r s t t r e e to appear i n the l i n e of v i s i o n on the r i g h t s i d e of the body to the r e a r of the e l e v a t e d arm. Th i s o r d e r was r e p e a t e d u n t i l a t o t a l of ten t r e e s had been samp led . Us ing the Hager hypsometer each t r e e was measured to f i n d i t s t o t a l h e i g h t , the h e i g h t to the f i r s t b r a n c h , the h e i g h t to the f i r s t l i v e branch and the h e i g h t of the ground v e g e t a t i o n n e a r e s t the base of the t r e e . From the measurements of the t o t a l h e i g h t and the h e i g h t to the f i r s t l i v e branch the l e n g t h of the l i v e crown was computed f o r each t r e e . From the ten measurements thus o b t a i n e d an average v a l u e f o r each f a c t o r was computed f o r each s t r i p . The f i n a l s t age of the p l o t measurement was to a s c e r t a i n the average age of the t r e e s . When t h i s i n f o r -mat ion was not a v a i l a b l e from s tand r e c o r d s the f o l l o w i n g p r ocedu re was a d o p t e d . As a l l s tands were even or near even a g e d o n l y f i v e t r e e s were s e l e c t e d a t t h i r t y f e e t i n t e r v a l s t h r oughou t the l e n g t h of the s t r i p u s i n g the same s e l e c t i o n p r ocedu re as o u t l i n e d above. Each s e l e c t e d t r e e was bored to o b t a i n a co re samp le . The annua l r i n g s of the co re sample were counted and an average age f o r the s t and o b t a i n e d . Where d i f f i c u l t y was encoun te red i n c o u n t -i ng the number of annual r i n g s , a s o l u t i o n of methe lene b l u e and m e l a c h i t e green was a p p l i e d to a c c e n t u a t e the l a t e wood. The enumera t i on was per fo rmed d u r i n g the f a l l o f 19 69 and w i n t e r of 1970. The v a l u e s o b t a i n e d were used f o r both the w i n t e r and summer a n a l y s i s w i t h the e x c e p t i o n of the v a l u e s f o r the h e i g h t of the ground v e g e t a t i o n i n a l l s t a n d s , and the h e i g h t of the f i r s t l i v e branch and l e n g t h of l i v e crown i n the dec iduou s s t a n d s . These v a l u e s were e i t h e r measured f o r the f i r s t t ime or remeasured i m m e d i a t e l y a f t e r the summer e xpe r imen t s to o b t a i n the sound p r e s s u r e l e v e l s . 4 .2 .2 A t t e n u a t i o n measurement. Th i s was a c o m p a r a t i v e measure. F i r s t l y an o u t - " l i n e of the t h e o r y beh ind the t e c h n i q u e i n v o l v e d . Over open ground sound i s a t t e n u a t e d by the f a c t o r s p r e v i o u s l y ment ioned i n Chap te r s II and I I I . Through a s t and of t r e e s ; and a d d i t i o n a l a t t e n u a t i o n takes p l a c e due to the p re sence of the v e g e t a t i o n . Th i s a d d i t i o n a l a t t e n u a t i o n i s known as the exces s a t t e n u a t i o n . To a s c e r t a i n the amount, of t h i s - exces s a t t e n u a t i o n one needs t o know the sound p r e s s u r e l e v e l t h a t e x i s t s when no t r e e s a r e ' p r e s e n t . When the se v a l u e s a re s u b t r a c t e d f rom the v a l u e s o b t a i n e d when t r e e s a re p r e s e n t then the exces s a t t e n u a t i o n i s f o u n d . There-., f o r e two s e t s of e xpe r imen t s a re run - one when t h e r e a re no t r e e s p r e s e n t and one when the v e g e t a t i o n s c r e e n i s p r e s e n t . Each p l o t , when enumerated , was measured i n such a way t h a t t h r e e s e t s of i n f o r m a t i o n were o b t a i n e d . W h i l s t the pa rameter s of t r e e h e i g h t s and h e i g h t of the ground v e g e t a t i o n were measured f o r the p l o t as a w h o l e , a l l o t h e r i n f o r m a t i o n was o b t a i n e d f o r b l o c k s 50 f e e t by-30 f e e t , 100 f e e t by 30 f e e t , and 150 f e e t by 30 f e e t i n s i z e . To match t h i s i n f o r m a t i o n the a t t e n u a t i o n a t each of t he se t h r e e d i s t a n c e s must be known. The sound s ou r ce was f i r s t s e t up a t the end of t h e . p l o t wh ich had been p r e v i o u s l y d e s i g n a t e d as the base l i n e end. The l o u d s p e a k e r was l o c a t e d on the c e n t r e l i n e o f the p l o t . The sound l e v e l meter was now s e t up a t a d i s t a n c e of 50 f e e t from the f r o n t edge of the l o u d s p e a k e r . The l o u d s p e a k e r was now s i g h t e d on the microphone of the sound l e v e l meter by means of the q u a r t e r i n c h groove cu t i n t h e . t o p of the l o u d s p e a k e r c a b i n e t . The r e s t of the appa ra tu s was now connec ted (see F i g u r e 10 ) . The a s s i s t a n t now s t a r t e d the tape r e c o r d e r and w a l k e d , a l ong the o u t -s i d e of the p l o t , to j o i n the person o p e r a t i n g the sound l e v e l m e t e r . Each f r e q u e n c y Tas ted f o r 60 seconds and the e i g h t f r e q u e n c i e s were i n t e r s p a c e d w i t h 20 seconds of b l ank t a p e . The f o u r r e a d i n g s t a k e n i n each s i x t y second p e r i o d were r e c o r d e d by the a s s i s t a n t . At 10 seconds and 40 seconds Figure 10- Schematic representation of equipment used to generate and measure the sound-A - Uher 4000 Report L Tape Recorder B - Delco Energiser Automobile Battery C - Bogen BT 35A Power Amplifier D - Marsland-Hawk 2-12 lOOw Loudspeaker E - Sound Level Meter £ a r e a d i n g was taken w i t h th-e-sound ' 1 e ve l meter a t s e t t i n g 'A . ' , and a t 25 seconds and 55 seconds w i t h the sound l e v e l meter a t s e t t i n g 'CV. Th i s p rocedu re was r e p e a t e d w i t h the sound l e v e l meter a t a d i s t a n c e of 100 f e e t and 150 f e e t f rom the sound s ou r ce i n a l l e i g h t e e n t r e e s t a n d s . G rea t c a r e must be taken to avo id ' a h i gh ambient n o i s e l e v e l when sound p r e s s u r e l e v e l s a re be ing measured. Examples a re a p a s s i n g c a r or a i r c r a f t . I f the n o i s e was of s h o r t d u r a t i o n i t was p o s s i b l e to o b t a i n f o u r r e a d i n g s by a l t e r i n g the t imes a t which they were r e a d . For l o n g e r d u r a t i o n n o i s e s the tape had to be. r e - r u n . Th i s drawback was l a r g e l y a v o i d e d by the remote l o c a t i o n of many of the s t and s and. by c o n d u c t i n g the e xpe r imen t s i n the v e r y e a r l y , morn ing i n those s t ands where a h i gh ambient n o i s e l e v e l was a p r ob l em. A t e c h n i q u e was d i s c o v e r e d (Gene ra l R a d i o , 1958 ) , a f t e r the w i n t e r da ta had been c o l l e c t e d , t h a t enab l ed a c o r r e c t i o n to be a p p l i e d to c o u n t e r a c t the e f f e c t of a h i gh ambient n o i s e l e v e l . B a s i c a l l y t h i s i n v o l v e d s u b t r a c t -i n g the ambient sound l e v e l f rom the measured sound p r e s s u r e l e v e l and a s c e r t a i n i n g , f rom a t a b l e , the c o r r e c t i o n , i n d e c e i b e l s , to be s u b t r a c t e d from the measured sound p r e s -s u re l e v e l . Th i s t e c h n i q u e was a p p l i e d to the summer d a t a . The p rocedu re adopted f o r the measurement of sound p r e s s u r e l e v e l s over open ground was i d e n t i c a l to t h a t used f o r the measurement of sound p r e s s u r e 1 e v e l s th rough a t r e e s c r e e n . Four s e r i e s of r e a d i n g s were taken - one over a s p h a l t , - one ove r mown g ra s s and two over s c r ub g r a s s -l and and bare sandy g round . A subsequent a n a l y s i s ' o f v a r i -ance f o r the open ground l o c a t i o n s showed no s i g n i f i c a n t d i f f e r e n c e between the sound p r e s s u r e l e v e l s r e c o r d e d f o r ea*ch. T h e r e f o r e , from the se f o u r l o c a t i o n s a mean sound p r e s s u r e l e v e l ove r open ground was c a l c u l a t e d f o r each s e t t i n g , a t each f r e q u e n c y , and a t each of the t h r e e d i s t a n c e s . The f o u r open ground l o c a t i o n s cove red the range of t e m p e r a t u r e s , wind s peed s , and r e l a t i v e h u m i d i t i e s r e c o r d e d i n the t r ee , s t ands so t he se t h r e e f a c t o r s c o u l d be e l i m i -nated f rom the e x p e r i m e n t a l d e s i g n . 4.3 C I i m a t o l o g i c a 1 F a c t o r s 4.3.1 Temperatu re and r e l a t i v e h u m i d i t y . As was s t a t e d e a r l i e r , i t was i n i t i a l l y hoped to match the t e m p e r a t u r e and r e l a t i v e h u m i d i t y of the t r e e s t a n d , a t the t ime of the sound p r e s s u r e l e v e l measurements , w i t h the open ground p l o t wh ich c o r r e s p o n d e d c l o s e s t , w i t h i n c e r t a i n s e t , l i m i t s . To t h i s e n d ' a s l i n g p s y c r o m e t e r r e a d i n g was taken a t the c e n t r e of each s tand i m m e d i a t e l y f o l l o w i n g the sound p r e s s u r e l e v e l measurements . From' the wet and d ry bu lb r e a d i n g s the r e l a t i v e h u m i d i t y was c a l c u l a t e d and the a i r t e m p e r a t u r e r e c o r d e d . As was l a t e r d i s c o v e r e d t h e r e e x i s t e d no s i g n i f i c a n t d i f f e r e n c e between the sound p r e s -su re l e v e l s measured a t the d i f f e r e n t t empe ra t u r e s and r e l a t i v e s - h u m i d i t i e s . A mean v a l u e was t h e r e f o r e c a l c u l a t e d f o r each f r e q u e n c y , a t each s e t t i n g , f o r each of the t h r e e d i s t a n c e s . Th i s v a l u e was s u b t r a c t e d from the c o r r e s p o n d i n g v a l u e o b t a i n e d th rough a t r e e s tand to g i v e v a l u e s f o r t h e , exces s a t t e n u a t i o n . No measurements were taken when the t e m p e r a t u r e v a r i e d by more than p l u s or minus 10 d e g r e e s , o r the r e l a t i v e h u m i d i t y by p l u s or minus 10 per cent , f rom the month l y mean. 4 . 3 .2 Wind Of a l l the c l i m a t i c f a c t o r s a f f e c t i n g sound a t t e n u a -t i o n , wind p r o b a b l y h a s the g r e a t e s t i n f l u e n c e . The nature, of i t s a f f e c t was d i s c u s s e d e a r l i e r i n Chap te r I I . The e x t e n t of the i n f l u e n c e of wind can be a l l but e l i m i n a t e d i f the l i n e between the sound s ou r ce and the sound r e c e i v e r i s a t r i g h t ang l e s to the d i r e c t i o n of the w i n d . However, as the p l o t s were pe rmanen t l y d e l i n e a t e d on the g r o u n d , i t was not a lways p o s s i b l e to w a i t f o r the wind to blow i n t h i s r e q u i r e d d i r e c t i o n . O b v i o u s l y i f t h e r e was no wind t h i s p a r t i c u l a r prob lem d i d not a r i s e . The open ground p l o t s were a lways l a i d out such t h a t the long a x i s was at r i g h t ang l e s t o the d i r e c t i o n of the w i n d . No r e a d i n g s were t aken when the wind speed was i n exces s of 440 f e e t per second (5 m i l e s per h o u r ) . The wind speed was measured b e f o r e , d u r i n g and a f t e r the sound p r e s s u r e l e v e l measure-ment u s i n g the A l n o r v e l o m e t e r J r . Once aga i n i t had been o r i g i n a l l y i n t e n d e d ' to match the open ground p l o t s w i t h the t r e e p l o t s on the b a s . i s ' o f wind speed , but the l a c k of any s i g n i f i c a n t d i f f e r e n c e between' the open ground p l o t s negated the n e c e s s i t y of do i ng t h i s . 4 . 4 . 3 O t h e r s . The o t h e r c l i m a t i c ' f a c t o r s of f o g , m i s t , snow, and t u r b u l e n c e were o m i t t e d from the d e s i g n by a p o l i c y of a v o i d a n c e . No measurements were done when snow l a y on the ground or was f a l l i n g , or when t h e r e was a m i s t , f og or r a i n shower. 'No measurements were taken when the v e g e t a -t i o n was w e t , e i t h e r f rom dew or f rom r a i n . T u r b u l e n c e i s a lmos t i m p o s s i b l e to d e t e c t , but the amount was c o n s i d e r e d so s m a l l t h a t i t c o u l d be i g n o r e d f o r a l l i n t e n t s and p u r p o s e s . 4.4 E x p e r i m e n t a l E r r o r s 4.4.1 P e r s o n a l and I n s t r u m e n t a l . P e r s o n a l e x p e r i m e n t a l e r r o r s a re bound to o c c u r i n the c o l l e c t i o n of any l a r g e amounts of da ta and undoub ted l y some o c c u r r e d i n t h i s p r o j e c t . A t t empt s were made to a v o i d e r r o r s by s t a n d a r d i z i n g the t e c h n i q u e s u sed . As the m a j o r i t y of the equipment used was new t h e r e s hou l d be l i t t l e unexpected i n s t r u m e n t a l e r r o r . The b a t -t e r i e s of the tape r e c o r d e r were kept f u l l y c h a r g e d , even though the s p e c i f i c a t i o n s of the i n s t r u m e n t were such t h a t a c o n s t a n t tape speed i s ' mai n t a i ned when the b a t t e r i e s a r e a lmos t f u l l y d i s c h a r g e d . The a u t o m o b i l e b a t t e r y was kept f u l l y charged to ensure a c o n s t a n t volume o u t p u t from the power a m p l i f i e r . The f r e q u e n c y of the r e c o r d e d sounds were checked on an o s c i l l o s c o p e as they were r e c o r d e d , and a subsequent check showed no more than a f i v e per c en t v a r i a t i o n a t any g i v e n f r e q u e n c y . The v e l o m e t e r was a d j u s t e d u s i n g the k i l n of the F e d e r a l F o r e s t P r oduc t s Research L a b o r a t o r y i n Vancouve r . Both sound l e v e l meters used were c a l i b r a t e d b e f o r e da ta • c o l l e c t i o n s t a r t e d . A s m a l l e r r o r must be e xpec t ed f rom the Hager hypsometer but as t h e f a c t o r s measured were a l l r e l a t i v e to one a n o t h e r t h i s can be l a r g e l y i g n o r e d . , 4 . 5 R e p r o d u c t i b i 1 i t y The e x p e r i m e n t a l t e c h n i q u e i s such t h a t i t can be r e p e a t e d f o r any v e g e t a t i o n type anywhere i n the w o r l d . Th i s a p p l i e s to f l a t ground and homogenous s t a n d s . Chapte r V PURPOSE OF THE ANALYSES AND THE DATA FORMAT 5.1 Purpose of the A n a l y s e s and the Data Format S e v e r a l d i f f e r e n t a n a l y s e s were per fo rmed on the c o l l e c t e d da ta w i t h the p r i m a r y aim of p r o v i n g o r d i s p r o v -i n g t he ; hypotheses l i s t e d i n Chapte r I I I . Secondary to t h i s main c o n s i d e r a t i o n , was the hope t h a t new i dea s and t hough t s would be produced by the r e s u l t s of the a n a l y s e s . 5 .2 Codi ng The f i e l d da ta p e r t a i n i n g to the t r e e s tands were f i r s t coded and then t r a n s f e r r e d onto F o r t r a n s hee t s t o be keypunched onto computer c a r d s . Each c a r d c o n t a i n e d the-f o l l o w i n g i n f o r m a t i o n f o r one f r e q u e n c y at one d i s t a n c e i n a p i o t . FACTOR CODING Stand number 1 - 1 8 W i n t e r or summer d a t a W i n t e r = 1 Summer = 2 D i s t a n c e 5 0 f t . = 1 , 1 0 0 f t . = 2 , 1 5 0 f t . B a s a l a r e a i n square f e e t per a c r e Number o f stems p e r a c r e FACTOR CODING S p e c i e s 1 = Cedar 2 = Hemlock 3 = Douglas f i r 4 = B i r c h 5 = A l d e r 7 = C h e r r y 8 = Stumps P e r c e n t a g e o f each s p e c i e s by b a s a l a r e a . H e i g h t t o t h e f i r s t b r anch i n f e e t . H e i g h t t o the f i r s t l i v e b r a n c h i n f e e t . L e n g th of the l i v e crown i n f e e t H e i g h t of the ground v e g e t a t i o n i n f e e t . Age i n y e a r s . Mean d i a m e t e r a t b r e a s t h e i g h t i n i n c h e s . Wind speed i n m i l e s per hour.. A i r t e m p e r a t u r e i n degrees F a h r e n h e i t . R e l a t i v e h u m i d i t y . Frequency 125 250 500 1 0 0 0 2 0 0 0 4000 8 0 0 0 1 2 0 0 0 c y c l e s c y c l e s c y c l e s c y c l e s c y c l e s c y c l e s c y c l e s c y c l e s per per per per per per per per second second second second second second second second 1 2 3 4 5 6 7 8 Sound l e v e l meter s e t t i n g A = 1 , C = 2 Sound p r e s s u r e l e v e l i n d e c i b e l s . The f i e l d da ta c o l l e c t e d when no t r e e s were , p r e s e n t were a l s o coded and r e c o r d e d on F o r t r a n f o r m s , f rom whence they were keypunched onto computer c a r d s . Each c a r d c o n t a i n e d i n f o r m a t i o n p e r t a i n i n g to one open ground p l o t a t one d i s t a n c e f o r one f r e q u e n c y . I n f o r m a t i o n was r e c o r d e d as f o l l o w s : FACTOR P l o t number W i n t e r o r summer d a t a D i s t a n c e Wind speed i n m i l e s p e r hour A i r t e m p e r a t u r e i n degrees F a h r e n h e i t . ' R e l a t i v e h u m i d i t y . Frequency •Sound l e v e l meter s e t t i n g ' Sound p r e s s u r e l e v e l i n d e c i b e l s CODING-1 - 4 ' ' W i n t e r = 1 , Summer = 2 5 0 f t . = 1 , 1 0 0 f t . = - 2 , 1 5 0 f t . = 3 1 2 5 250 500 1 0 0 0 2 0 0 0 4000 8 0 0 0 1 2 0 0 0 c y c l e s c y c l e s c y c l e s c y c l e s c y c l e s c y c l e s c y c l e s c y c l e s per per per per per per per per second second second second second second second second 1 2 3 4 5 6 7 8 A = 1- C = 2. 5.3 The A n a l y s e s An A n a l y s i s o f V a r i a n c e was done on the f o u r open ground p l o t s wh ich showed t h a t t h e r e was no s i g n i f i c a n t d i f -f e r e n c e between the sound p r e s s u r e l e v e l s a t the f i v e per cen t • s i g n f f i c a n c e l e v e l . A second programme produced a mean v a l u e , f rom the f o u r p l o t s , f o r the sound p r e s s u r e l e v e l a t each d i s t a n c e and f o r each f r e q u e n c y . A t h i r d programme s u b t r a c t e d the se v a l u e s f rom c o r r e s p o n d i n g t r e e s tand v a l u e s g i v i n g a f i g u r e f o r the a t t e n u a t i o n i n each s t a n d , a t each d i s t a n c e and a t each f r e q u e n c y . These v a l u e s were f i r s t o b t a i n e d as p r i n t e d ou tpu t wh ich was checked f o r v a l i d i t y . The nex t s t age was to produce a new s e t of punched ou tpu t c a r d s , each of wh ich c o n t a i n e d the p e r t i n e n t s tand i n f o r m a t i o n p r e v i o u s l y l i s t e d , p l u s the c a l c u l a t e d v a l u e f o r sound a t t e n u a t i o n . A l l s ub sequent a n a l y s e s were run on t h i s deck o f c a r d s . R e f e r r i n g , f o r a moment, to the hypotheses to be t e s t e d , i t w i l l be seen t h a t the m a j o r i t y h y p o t h e s i s e some t ype o f r e l a t i o n s h i p between sound a t t e n u a t i o n and the v a r i o u s s t and c h a r a c t e r i s t i c s . These hypotheses were t e s t e d u s i n g m u l t i p l e r e g r e s s i o n t e c h n i q u e s and the r e s u l t s and a . d i s c u s s i o n of them can be found i n Chap te r V I . The h y p o t h e s i s t h a t -The sound pressure level recorded at various distances through a screen of trees wi'll de-crease in proportion to the square of the distance from the sound source. was t e s t e d by p e r f o r m i n g numerous r e g r e s s i o n a n a l y s e s . Re-g r e s s i o n s were done on the r e s u l t s f o r each f r e q u e n c y i n each s t a n d , o f souhd p r e s s u r e l e v e l a g a i n s t the square of the d i s t a n c e , p r o d u c i n g va lues, f o r the R e g r e s s i o n . C o e f f i c -i e n t s , R and R s q u a r e d . Some examples of t he se r e s u l t s w i l l be shown i n Chap te r V I . The next s t age of the a n a l y s i s was to produce i n f o r m a t i o n on the a t t e n u a t i n g a b i l i t i e s of the d i f f e r e n t s p e c i e s . To t h i s end t a b l e s were p r o d u c e d , f o r each s p e c i e s , a t each d i s t a n c e , f o r each s t a n d , showing the a t t e n u a t i o n measured ' a t both sound l e v e l meter s e t t i n g s . A mean f i g u r e was c a l c u l a t e d , a t each f r e q u e n c y , f o r a l l the s t ands i n a s p e c i e s , t o g e t h e r w i t h i t s s t a n d a r d d e v i a t i o n . An a n a l y s i s o f v a r i a n c e was per fo rmed on the s tands w i t h i n a s p e c i e s to t e s t f o r s i g n i f i c a n t d i f f e r e n c e s between them. F i n a l l y a two way A n a l y s i s o f V a r i a n c e was done to t e s t f o r any i n t e r a c t i o n between- the v a r i o u s s tands and the d i f f e r e n t s ea son s . Chapte r VI RESULTS. AND DISCUSSION 6.1 Method of P r e s e n t a t i o n With so many d i f f e r e n t f a c t o r s and a n a l y s e s i n v o l v e d , t h i s c h a p t e r w i l l d i s c u s s the r e s u l t s i n the order- in- wh ich t h e : a n a l y s e s were p e r f o r m e d . A map showing the l o c a t i o n of the e i g h t e e n t r e e s tands can be found i n Append ix 1, and a d e s c r i p t i o n of the p h y s i c a l n a t u r e of t he se s t ands i n Append ix 2. The w i n t e r and summer c o r r e l a t i o n m a t r i c e s are r e p r o d u c e d , f o r each s p e c i e s , i n Append ix 3 and the a t t e n u a t i o n v a l u e s f o r each s t and i n Append ix 4. B l a c k and w h i t e photog raphs taken from each end of each 150 f o o t by 30 f o o t s t r i p can be found i n Append ix 5. 6.2 M u l t i p l e R e g r e s s i o n A n a l y s i s The . T r i a n g u l a r R e g r e s s i o n Package , known as U.B.C. T r i p B j e r r i n g e_t. aj_. (1 969 ), was the programme used f o r the f i r s t s t a ge o f the a n a l y s i s . Of the v a r i o u s programme o p t i o n s the s t e p w i s e b u i l d up was' the r o u t i n e cho sen . Th i s r o u t i n e has the t i t l e STPREG. B a s i c a l l y the ou tpu t of t h i s programme g i v e s the f o l l o w i n g i n f o r m a t i o n . A) The p a r t i a l l y i n v e r t e d c o r r e l a t i o n m a t r i x wh ich g i v e s the c o r r e l a t i o n c o e f f i c i e n t s of the de -pendent v a r i a b l e and a l l the- i ndependen t v a r i -a b l e s . .B) The c o e f f i c i e n t s i n the r e g r e s s i o n e q u a t i o n . C) The s t a n d a r d e r r o r of e s t i m a t e or the s t a n d a r d e r r o r of Y, Y be i ng the dependent v a r i a b l e . D) The s t a n d a r d e r r o r of the r e g r e s s i o n c o e f f i c i e n t s . E) The F r a t i o and a s s o c i a t e d p r o b a b i l i t y f o r each r e g r e s s i o n c o e f f i c i e n t . F) R s q u a r e d , the c o e f f i c i e n t of m u l t i p l e d e t e r -m i n a t i o n . 6) The F r a t i o and i t s p r o b a b i l i t y . S i m p l y , t h i s programme goes th rough a s e r i e s of r e g r e s s i o n a n a l y s e s add i ng and e l i m i n a t i n g the i ndependent v a r i a b l e s u n t i l i t a r r i v e s a t one, or a c o m b i n a t i o n of i ndependent v a r i a b l e s , wh ich g i v e s the be s t c o r r e l a t i o n . Each s t ep i n t h i s p r oce s s i s p r i n t e d i n the o u t p u t . The v a r i a b l e s used were as f o l l o w s : A) ' Dependent v a r i a b l e . . 1.. Excess sound a t t e n u a t i o n . B) Independent v a r i a b l e s . 1 . Ba sa l a rea . 2 . T-he. number of stems per a c r e . • 3 . The l e n g t h of c l e a r t ree - s tems. 4 . The . he i gh t of the f i r s t l i v e b r a n c h . 5. The l e n g t h of the l i v e c rown. 6. The h e i g h t of t h e ground/., v e g e t a t i o n . • 7 . Age. 8 . The average d i a m e t e r of the t r e e s a t b r e a s t h e i g h t . Though, i n many c a s e s , s i g n i f i c a n t R squared v a l u e s were o b t a i n e d t h e r e appeared no r e c o g n i z a b l e , p a t t e r n s among the v a r i a b l e s wh ich were c o r r e l a t e d w i t h exces s sound a t t e n u a t i o n . M u l t i p l e r e g r e s s i o n s were per fo rmed on each s p e c i e s a t each f r e q u e n c y , and the c o r r e l a t i o n m a t r i c e s a re to be found i n Append ix 3. Where a s i g n i f i c a n t r e l a t i o n -s h i p was found to e x i s t the number i n the c o r r e l a t i o n m a t r i x i s marked thus * . An e x a m i n a t i o n of the m a t r i c e s show t h a t f o r the w i n t e r r e s u 1 t s : . 14 t imes i n 64 7 t imes i n 64 6 t imes i n 64 6 t imes i n 64 6 t imes i n 64 6 t imes i n 48 4 t imes i n 3 2 1 t imes i n 32 no c o r r e l a t i o n Ba sa l a rea c o r r e l a t e d s i g n i f i c a n t l y Av. Diam. at b r e a s t h e i g h t c o r r e l a t e d s i g n i f i c a n t l y Stems per a c r e c o r r e l a t e d s i g n i f i c a n t l y Length of c l e a r b o l e c o r -r e l a t e d s i g n i f i c a n t l y H t . o f ground v e g e t a t i o n c o r r e l a t e d s i g n i f i c a n t l y . Age c o r r e l a t e d s i g n i f i c a n t l y Length o f crown c o r r e l a t e d s i g n i f i c a n t l y H t . to 1 s t . l i v e b ranch c o r r e l a t e d s i g n i f i c a n t l y And 28 o f the 64 p o s s i b i l i t i e s e x h i b i t e d w h a t s o e v e r . For the summer r e s u l t s Ba sa l a rea c o r r e l a t e d s i g n i f i c a n t l y Length of c l e a r bo l e c o r -r e l a t e d s i g n i f i c a n t l y Ht . to 1 s t . l i v e branch c o r r e l a t e d s i g n i f i c a n t l y Ht . of ground v e g e t a t i o n c o r r e l a t e d s i g n i f i c a n t l y Length of crown c o r r e l a t e d s i g n i f i c a n t l y Stems per a c r e c o r r e l a t e d s i g n i f i c a n t l y Av. Diam. a t b r e a s t h e i g h t c o r r e l a t e d s i g n i f i c a n t l y Age c o r r e l a t e d s i g n i f i c a n t l y 11 t imes i n 64 11 t imes i n 64 5 t imes i n 64 4 t imes i n 64 3 t imes i n 64 2 t imes i n 64 2 t imes i n 64 2 t imes i n 48 and 34 of the 64 p o s s i b i l i t i e s e x h i b i t e d no c o r r e l a t i o n w h a t s o e v e r . O b v i o u s l y the e x p e r i m e n t a l work has f a i l e d to f i n d the s t and c h a r a c t e r i s t i c or c h a r a c t e r i s t i c s t h a t cause a s t and of t r e e s to reduce n o i s e , o r , a t c e r t a i n f r e q u e n c i e s , to a m p l i f y i t . V a r i o u s causes a re though t to be the rea son f o r t h i s and they w i l l be b r i e f l y d i s c u s s e d . The obv i ou s reason i s t h a t , the s t and c h a r a c t e r i s t i c c a u s i n g a t t e n u a t i o n was not i n v e s t i g a t e d . V a r i o u s pa rameter s f a l l i n t o t h i s c a t e g o r y - namely , s p a t i a l d i s t r i b u t i o n , b ranch f o r m , need l e l e n g t h , l e a f s i z e , t r e e b i omas s , ground v e g e t a t i o n biomass and f a l l e n l o g s and l i t t e r . These f a c t o r s were not measured due to the t ime a v a i l a b l e and the d i f -f i c u l t y , i n some c a s e s , of o b t a i n i n g v a l i d measurements-. S p a t i a l d i s t r i b u t i o n may have some e f f e c t , but i f t h i s i s so a c l o s e r c o r r e l a t i o n w i t h the number of stems per a c r e might have been e x p e c t e d . Branch f o r m , need l e l e n g t h and l e a f s i z e ho l d more promise f o r f u t u r e i n v e s t i g a t i o n . I t has a l r e a d y been r e p o r t e d , i n Chap te r I I , t h a t re sonance of b ranches and l e a v e s may be a p o s s i b l e cause of the drop i n a t t e n u a t i o n around 1 000 .eye 1es per s e cond , 'and i t might not be ,unreasonab l e to assume t h a t they may have a d i f f e r e n t e f f e c t a t d i f f e r e n t f r e q u e n c i e s . The r e m a i n i n g f a c t o r s of t r e e and ground v e g e t a t i o n b i oma s s , and f a l l e n l og s and l i t t e r p r e s e n t more of a p r o b -l em. C u r r e n t work i n the F a c u l t y of F o r e s t r y a t the U n i v e r s i t y of B r i t i s h Co lumbia i s a t t e m p t i n g to f i n d a s i m p l e method o f e s t i m a t i n g t r e e biomass f rom e a s i l y mea-su red s t and c h a r a c t e r i s t i c s . I f t h i s work i s s u c c e s s f u l the p rob lem of measur ing t r e e biomass ; s h o u l d be e l i m i n a t e d . However, the s t and c h a r a c t e r i s t i c s under s t udy a re no d i f -f e r e n t f rom t ho se measured i n t h i s s t u d y , ( w i t h the e x c e p -t i o n of s p e c i f i c g r a v i t y - a c o n s t a n t w i t h i n a g i v e n s p e c i e s so i f t r e e biomass were to have an e f f e c t on sound a t t e n u a -t i o n , a s t r o n g e r c o r r e l a t i o n w i t h o n e ' o f the measured s t and f a c t o r s would have b e e n e x p e c t e d . The ground v e g e t a t i o n p r e s e n t s problems of a d i f -f e r e n t n a t u r e . A l t hough t h i s ' s t udy was p r i m a r i l y i n t e r -e s t e d i n the a t t e n u a t i n g a b i l i t i e s of t r e e s , the ground v e g e t a t i o n o f t he se s tands must a f f e c t the a t t e n u a t i o n i n some way. The' n a t u r e and amount of the ground v e g e t a t i o n p r e s e n t i s the r e s u l t of the s o i l , the c l i m a t e , and the n a t u r e , s i z e and age of the t r e e o v e r s t o r e y . The pa rameter o f the h e i g h t of the ground v e g e t a t i o n , used i n t h i s s t u d y , s h o u l d be r e p l a c e d by some o t h e r f a c t o r . No accoun t i s t aken of the d i s t r i b u t i o n o f the v e g e t a t i o n t h r oughou t a s t and or of i t s d e n s i t y . Embleton (1963) a t t empted to prove a r e l a t i o n s h i p between o p t i c a l v i s i b i l i t y and sound a t t e n u a -t i o n . H i s r e s u l t s d e p i c t e d no obv i ou s c o r r e l a t i o n . An a l t e r n a t i v e measure may be found i n the biomass of the ground v e g e t a t i o n . Randomly s c a t t e r e d one metre square quad ra t s c o u l d be used to o b t a i n v e g e t a t i o n s amp le s . These samples would then be d r i e d and weighed to g i v e an e s t i m a t e o f b i omas s . A l t e r n a t i v e l y , a measure of the p e n e t r a b i l i t y of the v e g e t a t i o n c o u l d be t a k e n . One pos -s i b l e method of do i ng t h i s i n v o l v e s the use of a s t a n d a r d s i z e d w h i t e c a rd and a camera. The w h i t e ca rd would be a r r anged p e r p e n d i c u l a r to the ground a t random l o c a t i o n s t h r o u g h o u t the p l o t and photographed f rom a c o n s t a n t d i s -t ance away. By the use o f g r i d o v e r l a y s , the amount of c a rd c o ve red by the v e g e t a t i o n c o u l d be e a s i l y d e t e r m i n e d . Th i s i ndex of v i s i b i l i t y would then be t e s t e d f o r c o r r e l a -t i o n . The l a s t f a c t o r of l og s and l i t t e r i s e x t r e m e l y hard to q u a n t i f y , and the on l y method t h a t can be thought of i s t h a t sugges ted f o r measurement of the ground v e g e t a t i o n . Randomly s e l e c t e d one metre square q u a d r a t s would be used to o b t a i n l o g and l i t t e r s amp les . The samples would be d r i e d and weighed to o b t a i n a measure of the b i omas s . Of a l l t he se f a c t o r s i t i s sugges ted t h a t a s tudy of b ranch and l e a f form and the ground v e g e t a t i o n would be the most r e w a r d i n g . 6 .3 The I n ve r se Square Law The next s t age of the a n a l y s i s was to t e s t the h y p o t h e s i s t h a t : The sound -pressure level recorded at various i n t e r v a l s through a screen of trees w i l l decrease in proportion to the square of the distance from the sound source. Th i s was done w i t h a s e r i e s of 288 s e p a r a t e s i m p l e r e g r e s -s i o n s of the d i s t a n c e squared a g a i n s t the sound p re s su re , l e v e l measured at t h a t d i s t a n c e . Here the f i r s t major drawback i n the e x p e r i m e n t a l d e s i g n became o b v i o u s . With a r e g r e s s i o n r e l a t i o n s h i p of on l y t h r e e numbers an R squared v a l u e of 0.997 i s r e q u i r e d f o r the r e l a t i o n s h i p to be s i g n i f -i c a n t a t the 5% l e v e l . O b v i o u s l y to t e s t . t h i s h y p o t h e s i s p r o p e r l y , r e a d i n g s of the sound p r e s s u r e l e v e l would need to be taken a t l o c a t i o n s between and beyond the t h r e e s e l e c t e d d i s t a n c e s . However, the a n a l y s i s was done and a r e l a t i o n s h i p wh ich proved the h y p o t h e s i s was found to be s i g n i f i c a n t at the 5% l e v e l i n o n l y 44 of the 288 a n a l y s e s , or 1 4 . 1% , and i n 23 of the 288 a n a l y s e s a t the 1% s i g n i f i c a n c e l e v e l , or 8.0%. Th i s a n a l y s i s was done f o r the w i n t e r da ta and was deemed not worth r e p e a t i n g f o r the summer d a t a . 6.4 A t t e n u a t i o n Va lues A l t h o u g h , thus f a r , no r e l a t i o n s h i p can be shown to e x i s t between a t t e n u a t i o n and the s tand c h a r a c t e r i s t i c s , the e x p e r i m e n t a l work d i d produce i n f o r m a t i o n on the a t t e n u -a t i n g a b i l i t i e s o f e i g h t e e n s t ands compr i sed of f o u r d i f -f e r e n t s p e c i e s . I t would seem l o g i c a l to assume t h a t i f t he se e i g h t e e n s t ands e x h i b i t e d d i f f e r e n t a t t e n u a t i n g a b i l -i t i e s i t would be a f a c t o r o f the p h y s i c a l pa rameter s of the d i f f e r e n t s t a n d s . I t might even be l o g i c a l to e xpec t t h a t d i f f e r e n t pa rameter s would e x e r t the a t t e n u a t i n g i n f l u e n c e a t d i f f e r e n t f r e q u e n c i e s . However, a l l a n a l y s e s have f a i l e d to show any such r e l a t i o n s h i p . Methods of d i s -c o v e r i n g t h i s r e l a t i o n s h i p w i l l be d i s c u s s e d * l a t e r . I t i s f e l t , t h a t w h i l e no r e l a t i o n s h i p has been f o u n d , the da ta produced can be o f v a l u e to many p l a n n i n g bod i e s i n the l ower main. l and r e g i o n of B r i t i s h C o l u m b i a . I n f o r m a t i o n was o b t a i n e d on the a t t e n u a t i n g a b i l i t i e s of d i f f e r e n t t r e e s tands and w i l l s e r v e as a gu ide of what may be e xpec ted from s i m i l a r s t a n d s . With t h i s end i n v iew the f o l l o w i n g graphs are p r e s e n t e d . In i n t e r p r e t i n g the da ta from the se f i g u r e s , r e f e r e n c e shou ld a l s o be made to the Tab l e s and to the s tand photographs i n Append i ce s 2, 4 , and 5. 6.5 The A n a l y s e s of V a r i a n c e W i t h i n each s p e c i e s , an a n a l y s i s of v a r i a n c e showed t h a t f o r c e r t a i n s t and s in each s e a s o n , t h e r e was no s i g n i f i c a n t d i f f e r e n c e , a t the 5 % . l e v e l , between t h e i r a t t e n u a t i n g a b i l i t i e s . However, i n the m a j o r i t y of s t a n d s , as was e x p e c t e d , t h e r e e x i s t e d q u i t e wide d i f f e r e n c e s i n a t t e n u a t i n g a b i l i t i e s . D e s p i t e t he se d i f f e r e n c e s between the s t a n d s , i t was f e l t t h a t the e a s i e s t way to show the d i f f e r e n c e i n a t t e n u a t i n g a b i l i t y , and the v a r i a n c e of a t t e n u a t i o n w i t h f r e q u e n c y , was to use the mean f i g u r e s , f o r a l l s tands w i t h i n a s p e c i e s . These r e s u l t s a re d e p i c t e d g r a p h i c a l l y , a t each d i s t a n c e , w i t h both w i n t e r and summer r e s u l t s on one g r a p h , i n F i g u r e s 11 to 14. An e x a m i n a t i o n of the graphs r e v e a l s t h a t the t y p i c a l ' S ' shaped c u r v e , d i s c u s s e d i n the 1 i t e r a t u r e r e v i e w , i s to be found i n a l l spec ie s . . In a l l s p e c i e s the g r e a t e s t a t t e n u -a t i o n i s found a t 250 c y c l e s per second and the l o w e s t a t t e n u -a t i o n , sometimes even n e g a t i v e , be i ng found between 500 and 2,000 c y c l e s per s e cond . These r e s u l t s a re c o n s i s t e n t w i t h those of E y e r i n g ( 1946 , Hess and K u r s t e i n e r " ( 1 9 6 1 ) , and Embleton ( 1963 ) . I = Winter 2= Summer Season does not appear to a f f e c t the p a t t e r n of a t t e n u a t i o n a t the d i f f e r e n t f r e q u e n c i e s . G e n e r a l l y speak -i ng s l i g h t l y h i g h e r v a l ue s f o r a t t e n u a t i o n are o b t a i n e d i n the summer i n a l l s p e c i e s , e x cep t a t the 4,000 and 8,000 c y c l e s per second f r e q u e n c i e s , when the w i n t e r v a l u e s a re s l i g h t l y h i g h e r . One f e a t u r e , s eem ing l y appa ren t f rom the g r a p h s , and not p r e v i o u s l y r e p o r t e d , i s a peak ing of excess, a t t e n u -a t i o n v a l u e s at 100 f e e t . A marked i n c r e a s e i n exces s a t t e n u a t i o n from 50 f e e t to 100 f e e t i s f o l l o w e d by ve r y s i m i l a r v a l u e s f o r 100 f e e t and 150 f e e t . The measured n o i s e v a l u e s a re l ower a t the l o n g e r d i s t a n c e s but the r a t e of a t t e n u a t i o n or the a t t e n u a t i o n c o e f f i c i e n t s appear to d i f f e r a t the t h r e e d i s t a n c e s . The a t t e n u a t i o n c o e f f i c i e n t s are o b t a i n e d by d i v i d i n g the a t t e n u a t i o n v a l u e s by the d i s t a n c e a t wh ich each v a l u e was measured. Th i s g i v e s a measure of a t t e n u a t i o n i n d e c i b e l s a t t e n u a t e d per l i n e a l f o o t . A t t e n u a t i o n c o e f f i c i e n t s f o r the average a t t e n u a -t i o n w i t h i n a l l s t ands o f a s p e c i e s , over a l l f r e q u e n c i e s are l i s t e d be low. Compar i son of A t t e n u a t i o n C o e f f i c i e n t s ATTENUATION COEFFICIENTS SPECIES DISTANCE IN DECIBELS ATTENUATED PER LINEAL FOOT WINTER SUMMER Douglas f i r 50 f t . 0.073 0.075 Douglas f i r 100 f t . 0.070 0.088 Douglas f i r 150 f t . 0.049 0,070 M i x t u r e 50 f t . 0.108 0.090 M i x t u r e - 100 f t . 0.098 0 .0-9-2 M i x t u r e 150 f t . 0.051 0.058 Al der 50 f t . 0.139 0.128 A l der 100 f t . 0.084 0.093 A l d e r 150 f t . 0.056 0.069 B i r c h 50 f t . 0.061 0.051 B i r c h 100 f t . 0.047 0.040 B i r c h 150 f t . 0.028 0.046 In t h e o r y the r a t e of sound a t t e n u a t i o n s hou ld remain c o n s t a n t t h r oughou t the l e n g t h of the s t a n d . However, an a n a l y s i s o f v a r i a n c e showed t h a t a s i g n i f i c a n t d i f f e r e n c e at . the 5% l e v e l o f s i g n i f i c a n c e , e x i s t e d between the a t t e n -u a t i o n c o e f f i c i e n t s a t the t h r e e d i s tances . . . A subsequent Duncans M u l t i p l e Range t e s t showed t h a t the 50 f t . c o e f -f i c i e n t s d i f f e r e d s i g n i f i c a n t l y a t the 5% l e v e l f rom those at 100 f t . and 150 f t . , and t h a t the c o e f f i c i e n t s f o r 150 f t . were s i g n i f i c a n t l y d i f f e r e n t f rom those a t 50 f t . and 100 f t . The reason f o r t h i s d i f f e r e n c e i s not known but one p o s s i b l e h y p o t h e s i s w i l l be o f f e r e d . C o n s i d e r two d i f f e r e n t p l o t s - one over open ground and one th rough a s t and of t r e e s . Sound p r e s s u r e l e v e l s are measured a t the t h r e e d i s t a n c e s of 50 f t . , 100 f t . , and 150 f t . These produce the v a l u e s X l 5 Y i ,: and Z i , f o r the open ground p l o t , and the v a l u e s X 2 , Y 2 , and Z 2, f o r the t r e e s kand . By s u b t r a c t i o n of the t r e e s t and v a l u e s f rom the c o r r e s p o n d i n g open ground v a l u e s , the amount o f sound a t t e n u a t i o n caused by the t r e e s tand i s o b t a i n e d , v i z . X i - X 2 = X Y i - Y 2 = Y Zi - Z 2 = Z where X i s the a t t e n u a t i o n at 50 f t . , - Y a t 100 f t . , and Z at 150 f t . In t h e o r y i f the r a t e of a t t e n u a t i o n i s c o n -s t a n t t h r o u g h o u t the l e n g t h of the s tand _X_ _ __Y__ _ _Z_ 50 100 150 * 1 However, the A n a l y s i s o f V a r i a n c e showed t h a t t h i s was not s o , and t h a t i n f a c t , 50 100 1 50 The a c t u a l f i g u r e s over a l l s p e c i e s a r e : _X_ 50 0.0908 Y 0.0765 100 Z 0.0534 150 What appears to be happen ing i s t h a t l a r g e r than e xpec ted v a l u e s f o r the sound p r e s s u r e l e v e l a re be i ng measured a t the l o n g e r d i s t a n c e s . As was p r e v i o u s l y s t a t e d , the reason f o r t h i s i s unknown, but one p o s s i b l e rea son i s as f o l l o w s . I t was s t a t e d , i n Chapte r I I , t h a t sound waves d i f f r a c t f rom an open ing to an even g r e a t e r e x t e n t than l i g h t waves. Th i s w i l l r e s u l t i n s e v e r a l waves r i s i n g a n d ' t h i s i s one reason f o r the a t t e n u a t i o n of sound over open g round . The same waves i n a t r e e s tand w i l l a l s o r i s e but t h i s t ime w i l l e v e n t u a l l y meet the o b s t r u c t i o n of the t r e e s canopy . They may be a b s o r b e d , or r e f l e c t e d . Some w i l l be r e f l e c t e d backwards or upwards thus c a u s i n g a . l o s s i n the t o t a l energy of the sound a t some p o i n t f u r t h e r away, and hence an a t t e n u a t i o n . However, not a l l waves w i l l b e . r e f 1 e c t e d backwards or upwards, some w i l l be r e f l e c t e d back down towards the ground and w i l l thus cause the energy a t some p o i n t f u r t h e r away to be s l i g h t l y g r e a t e r t han , e x p e c t e d . T h i s would i n t u r n cause the sound p r e s s u r e • l e v e l s a t the l o n g e r d i s t a n c e s to have a s i i g h t l y g r e a t e r -v a l u e than e x p e c t e d . D i f f e r e n c e s i n the a t t e n u a t i n g a b i l i t i e s of the d i f f e r e n t s p e c i e s were not as l a r g e as was e x p e c t e d . Some o v e r a l l d i f f e r e n c e s a re a p p a r e n t . Of a l l the s p e c i e s , the M i x t u r e and the A l d e r s t ands gave the bes t a t t e n u a t i o n . These s p e c i e s were f o l l o w e d by Dou.glas f i r w i t h B i r c h g i v i n g the l o w e s t v a l u e s f o r a t t e n u a t i o n . Douglas f i r i s p l a c e d ahead of the B i r c h by v i r t u e of h i g h e r v a l u e s of exces s a t t e n u a t i o n i n the m i d d l e f r e q u e n c i e s . 6.6 The Two-Way A n a l y s i s o f V a r i a n c e The f i n a l s t age of the a n a l y s i s was to t e s t f o r the e f f e c t o f the d i f f e r e n t . s e a s o n s on the a t t e n u a t i o n of sound. To t h i s end a Two-Way A n a l y s i s of V a r i a n c e was p e r f o r m e d , u s i n g the v a r i a b l e s of s t and and s ea son . The g r a p h i c a l r e s u l t s of t h i s a n a l y s i s a re r ep roduced i n F i g u r e s 15 to 18. An e x a m i n a t i o n o f the graphs shows t h a t s t ands tend to a c t i n d e p e n d e n t l y of each o t h e r and t h a t the re sponse to season v a r i e s among the d i f f e r e n t s t ands of a s p e c i e s . I t would appear from the graphs t h a t g e n e r a l l y Figure 15- Mean attenuation for each stand in summer and _ 8 3 _ winter for Douglas-fir-2 3 4 Stand I 2 3 4 Stand l=Winter 2= Summer Figure 16- Mean attenuation for each stand in summer a n d - 8 4 Winter for the mixture-Figure 18- Mean attenuation for each stand in summer and winter for alder-1= Winter 2 = Summer . 50 feet 5 Stand 100 feet 5 Stand 150 feet 5 Stand Figure 17- Mean attenuation for each stand in summer and winter for birch-CD X I O a> O c o o z> c cu 50 feet 4 Stand cu x> "o CU O c o 100 feet o Z3 cu 2 4 Stand cu X > • o cu O c o o C CU 150 feet 4 Stand 1= Winter 2= Summer s p e a k i n g , the summer v a l u e s f o r a t t e n u a t i o n are s l i g h t l y h i g h e r . However, o n l y i n two i n s t a n c e s out of t w e l v e were the summer r e s u l t s s i g n i f i c a n t l y d i f f e r e n t f rom the w i n t e r r e s u l t s a t the 5% l e v e l of s i g n i f i c a n c e . The two i n s t a n c e s were Douglas f i r and B i r c h a t the 150 f t . d i s t a n c e . To a i d i n t e r p r e t a t i o n of t he se f i g u r e s the graphs f o r B i r c h w i l l be b r i e f l y d e s c r i b e d . At 50 f t . and 100 f t . t h e r e e x i s t s l i t t l e d i f f e r e n c e between the graph p a t -t e r n s . The v a l u e s a t 100 f t . a re s l i g . h t l y l a r g e r than tho se a t 50 f t . but the two graphs f o l l o w r o u g h l y the same shape , i . e . s t and 3 g i v e s t h e . g r e a t e s t v a l u e s f o r a t t e n u a t i o n . In a l l s t ands e x cep t s t and 4 the w i n t e r r e s u l t s show g r e a t e r a t t e n u a t i o n than do those f o r summer. However, at 150 f t . d i f f e r e n t c i r c u m s t a n c e s p r e v a i l . T h e r e , the summer r e s u l t s show g r e a t e r a t t e n u a t i o n and re sponse seems to be r e l a t i v e l y even f o r each s ea s on . Chapte r V I I IMPLICATIONS OF RESULTS 7.1 I n t r o d u c t i o n The i m p l i c a t i o n s of the r e s u l t s a re both many and v a r i e d and w i l l be d e a l t w i t h i n the v a r i o u s a rea s to wh ich they a p p l y . Be f o re any s t ep s can be taken to. reduce, n o i s e from any s o u r c e , t h r e e t h i n g s must f i r s t be a s c e r -t a i n e d ? 1 . The present or expected noise l e v e l s at the l o c a t i o n where excessive noise i s , or i s expected to be, a problem... 2. A frequency a n a l y s i s of the noise. 3. The d e s i r e d noise l e v e l s . As can be seen from the r e s u l t s i n Chap te r V I , a d e t e r m i -n a t i o n of the f r e q u e n c y of the n o i s e i s o f paramount i m -p o r t a n c e , as t r e e s have l i t t l e or no a t t e n u a t i n g a b i l i t i e s a t c e r t a i n f r e q u e n c i e s . The a c t u a l and d e s i r e d n o i s e v a l u e s w i l l p r o v i d e a f i g u r e f o r the a c t u a l a t t e n u a t i o n des i r e d . 7.2 Landscape Des ign Th i s s e c t i o n w i l l d i s c u s s the p h y s i c a l d e s i g n i m p l i -c a t i o n s o f u s i n g t r e e s c r e e n s to reduce n o i s e . The p a r t of the s tudy wh ich had the g r e a t e s t i m p l i -c a t i o n s to l a n d s c a p e d e s i g n was t h a t p a r t wh ich a t t empted to d i s c o v e r j u s t what i t was i n a s tand of t r e e s t h a t causes sound a t t e n u a t i o n . As the s tudy f a i l e d to show what t h i s f a c t o r was, the l a nd s cape i m p l i c a t i o n s a re s a d l y a l l too few. We do have i n f o r m a t i o n f o r a v a r i e t y of s t and s w i t h i n f o u r s p e c i e s and we do know which of t he se f o u r s p e c i e s g i v e the b e t t e r a t t e n u a t i o n s . The l a nd s cape a r c h i t e c t , g i v e n the s p e c i e or s p e c i e s w i t h which he has to work , i s p r i m a r i l y conce rned w i t h the p h y s i c a l a r r a n g e -ment of the p l a n t s to produce the d e s i r e d e f f e c t . U n f o r -t u n a t e l y the s t udy d i d not y i e l d i n f o r m a t i o n r e g a r d i n g the r o l e p l a yed by a v e g e t a t i o n u n d e r s t o r e y or by the s p a t i a l a r rangement • of t r e e s . Th i s i s o b v i o u s l y a t o p i c f o r f u t u r e work and w i l l be d i s c u s s e d f u r t h e r i n t h e f i n a l c h a p t e r . Three of the f o u r s p e c i e s examined were n a t u r a l l y r e g e n e r a t e d s t a n d s , the f o u r t h , Douglas f i r , be ing p l a n t e d . Thus , the s t udy y i e l d e d i n f o r m a t i o n on o n l y f o u r a r t i f i c -i a l l y c r e a t e d s t a n d s . A l t h o u g h more da ta are r e q u i r e d i t i s a n t i c i p a t e d t h a t the r e s u l t s f rom Douglas f i r w i l l be of the most v a l u e i n the c r e a t i o n of p l a n t e d t r e e s c r e e n s . As A l d e r grows both r a p i d l y and r e a d i l y i n the l ower ma in l and a rea of B r i t i s h Co lumbia i t i s hoped t h a t t he se r e s u l t s w i l l a l s o be of much use to the d e s i g n e r s of t r e e s c r e e n s . The M i x t u r e and B i r c h r e s u l t s w i l l be of use when the use of a l r e a d y e x i s t i n g t r e e s t ands i s a n t i c -i p a t e d , as t he se s p e c i e s a re the t r e e t ype s p redominant i n the l ower ma in l and of B r i t i s h C o l u m b i a . H o p e f u l l y , w i t h more i n f o r m a t i o n , i t w i l l be p o s s i b l e to c r e a t e l a nd s caped t r e e s c r een s a l o n g s i d e f reeways and i n d u s t r i a l a r e a s . The i n f o r m a t i o n s u p p l i e d by t h i s s t udy i s but a s m a l l p a r t of the t o t a l i n f o r m a t i o n r e q u i r e d b.ut s hou l d enab l e a s t a r t to be made i n the use of t r e e s to reduce f i o i s e . 7.3 I n d u s t r i a l Des ign The r e s u l t s of t h i s s u r vey a p p l y to two a rea s of i n d u s t r i a l n o i s e c o n t r o l . The f i r s t of t he se i s the r e d u c -t i o n of n o i s e from e x i s t i n g i n d u s t r i a l p l a n t . There a re many and v a r i e d methods of r e d u c i n g i n d u s t r i a l n o i s e . The n o i s e s ou r ce i t s e l f must a lways be the p r i m a r y t a r g e t f o r r e d u c t i o n by ' r e - d e s i g n or m o d i f i c a t i o n of the m a c h i n e r y . S e c o n d l y , wo rke r s w i t h i n the f a c t o r y may be p r o t e c t e d , e i t h e r by e n c l o s i n g wo r k i n g a r e a s , or by the use of e a r -p l u g s . I f , however , a f a c t o r y i s l o c a t e d i n a r e s i d e n t i a l a r e a , the g e n e r a l n o i s e emanat ing, f rom the p l a n t may become a p u b l i c n u i s a n c e . The f r e q u e n c y of the n o i s e produced by a f a c t o r y w i l l o b v i o u s l y v a r y w i t h the na tu re of the f a c t o r i e s . An example of t h i s i s g i v e n by Hosey and Powe l l ( 1 967 ) , when they quote from da ta taken from the No i se Manual - Amer i can I n d u s t r i a l Hyg iene A s s o c i a t i o n . Th i s da ta y i e l d s i n f o r m a t i o n on two i n d u s t r i a l n o i s e s o u r c e s : a f o r g i n g hammer and an a n n e a l i n g f u r n a c e . The peak n o i s e v a l u e s f rom the hammer are found i n the l ower f r e q u e n c i e s , 37.5 to 150 c y c l e s per s e c o n d , a f t e r wh ich the n o i s e v a l u e s f a l l o f f q u i t e r a p i d l y . The f u r n a c e , on the o t h e r hand, has l ower n o i s e v a l u e s i n the l ower f r e q u e n c i e s b u i l d i n g up to a peak at 1200 c y c l e s per s e cond . Both sound sou rce s have s i m i l a r n o i s e v a l u e s over a l l f r e q u e n c i e s . Hence, f rom the s t udy r e s u l t s a t r e e s c r een might o f f e r u s e f u l s o u n d , a t t e n u a t i o n f o r the f o r g i n g hammer but not f o r the a n n e a l i n g f u r n a c e . B o n v a l l e t ( 1 951 ) , i n v e s t i g a t e d the f r e q u e n c y s p e c t r a and l e v e l s of i n d u s t r i a l n o i s e . In over a hundred measure-ments .he d i s t i n g u i s h e s between i n d u s t r i a l n o i s e measured which was above the background n o i s e , and i n d u s t r i a l n o i s e measured below the background n o i s e . From h i s r e s u l t s he produced a graph showing average n o i s e l e v e l s i n i n d u s t r i a l a rea s over a f r e q u e n c y range of 0 to 4800 c y c l e s per second T h i s graph i s r ep roduced below i n F i g u r e 19. Dots r e p r e s e n t n o i s e l e v e l s above the background n o i s e , c i r c l e s n o i s e l e v e l s below i t . The upper l i n e i n the graph d e p i c t s a sugges ted a c c e p t a b l e n o i s e l e v e l s p e c -t r um. The f r e q u e n c i e s hav ing the h i g h e s t pe r cen tage of • SUGGESTED UUlTWS SPECTRUM. TEN PERCENT OF THE CASES »tfi£ *BOVE THIS CURVE ZOO 500 400 600 800 1200 KOO « 0 0 ISOO ALL SO KO rSO £00 lOO 400 COO 100 l!00 WOO f.OO 5200 <5CO CD OCTAVE BANCS, CPS FIG. 19 Average noise levels in industrial areas. The approximate distance to the property line in each case was 25 ft. About 90 percent or more of the industries were below the upper curve which is a suggested limiting spectrum. OVLK- O SO TS 100 ISO tOO SOO 400 400 6CO IWO 1600 MOO 4BOO ALL SO tOO 130 K O 300 400 COO BOO COO 15CO J4CO 3200 4SOO CO OCTAVE tAKDS, CPS FIG.ZO. Average noise levels of heavy, average, and light traffic conditions. Readings were made with vehicles at 25 to 50 feet for heavy traffic, and at 100 feet or more for average or light traffic. ( A f t e r B o n v a l l e t , 1951) dots n e a r e s t the upper l i m i t i n g l i n e are the l ower ones up to around 800 c y c l e s per second and t h i s f a c t augers w e l l f o r the. s u i t a b i l i t y of t r e e s c reen s to a t t e n u a t e i n d u s t r i a l n o i s e . The s u i t a b i l i t y of p l a n t i n g a t r e e s c reen w i l l depend on the f a c t o r y l o c a t i o n . O l d e r f a c t o r i e s tend to have been b u i l t c l o s e to the p e r i m e t e r of l o t s , w h i l e the newer ones tend to be more s p a c i ou's , be i ng su r rounded by.open g round . However, the method of n o i s e c o n t r o l s t u d i e d i n t h i s t h e s i s may have a more i m p o r t a n t r o l e to p l a y i n d e c i s i o n s on the l o c a t i o n o f new i n d u s t r i a l p l a n t . Where p r e v i o u s l y a l l i n d u s t r i a l l and has been c l e a r e d of t r e e s p r i o r to b u i l d i n g i t may be w e l l worth w h i l e to l e a v e as many t r e e s s t a n d i n g as i s p o s s i b l e i n the form of a b u f f e r a r e a , as an a i d . to n o i s e a t t e n u a t i o n . A p a r t f rom the a c t u a l n o i s e r e d u c t i o n caused the t r e e s w i l l a c t as a u s e f u l v i s u a l b a r r i e r , and as ment ioned e a r l i e r t h i s has a p sy -c h o l o g i c a l e f f e c t on the n o i s e p e r c e i v e d by an i r i d i v i d u a l . In summat ion, i n c e r t a i n cases t r e e s c reens a re seen as an-answer to n o i s e problems but s hou ld not be r ega rded as a cu re a l l . 7.4 Highway Des ign In the i n v e s t i g a t i o n a l r e a d y r e f e r r e d t o , B o n v a l l e t (op. c i t . ) , a l s o conduc ted e xpe r imen t s to d e t e r m i n e l e v e l s and s p e c t r a of t r a f f i c and r e s i d e n t i a l n o i s e . He i n v e s t i -gated heavy , ave rage and l i g h t t r a f f i c c o n d i t i o n s and p r o -duced the f o l l o w i n g , graph from h i s r e s u l t s (see F i g u r e 2 0 ) . As can be seen from the g r a p h , the h i g h e s t n o i s e l e v e l s a re f o u n d , i n a l l c a s e s , i n the l ower f r e q u e n c i e s , between 0 and 500 c y c l e s per s econd . Th i s c o r r e s pond s v e r y f a v o u r a b l y w i t h the f r e q u e n c i e s a t wh ich t r e e s cause most sound a t t e n u a t i o n . B e f o r e expand ing on the r o l e of t r e e s i n a t t e n u a t i n g highway gene r a t ed n o i s e . o n e or two o t h e r f a c t o r s must be m e n t i o n e d . G a l l o w a y , C l a r k e t . aj_. ( 1 969 ), i n a comprehen-s i v e r e p o r t on highway n o i s e , make-a number of o b s e r v a t i o n s . They compare the a t t e n u a t i n g a b i l i t i e s of v a r i o u s road d e s i g n s and f o u n d , over d i s t a n c e , roads c o n s t r u c t e d on grade had the l e a s t n o i s e r e d u c t i o n . E l e v a t e d roadways gave the be s t a t t e n u a t i o n a t s h o r t d i s t a n c e s but had l i t t l e r e sponse to the e f f e c t of i n c r e a s e d d i s t a n c e from the n o i s e s o u r c e . The be s t d e s i g n s were those w i t h a v e r t i c a l - o r s l o p e d c u t , the f o rmer be i ng s l i g h t l y b e t t e r . They have a l s o deve l oped a s i m u l a t i o n model f o r p r e d i c t i n g t r a f f i c n o i s e , based on the f a c t o r s of t r a f f i c f l o w i n v e h i c l e s per h o u r , d i s t a n c e i n f e e t to the p s e u d o - l a n e , and average t r a f f i c speed i n m i l e s per hour . They can a l s o p r e d i c t the e f f e c t s o f v a r i o u s pe r cen t a ge s o f t r u c k s i n the t r a f f i c . Th i s knowledge t o g e t h e r w i t h i n f o r m a t i o n r e g a r d i n g the d e s i r e d n o i s e l e v e l a t a s e t d i s t a n c e f rom the a c t u a l or p r o j e c t e d highway shou ld g r e a t l y a s s i s t p l a n n e r s . G i ven the b a s i c t o o l s o u t l i n e d above , p l u s the f a c t t h a t t r e e s can reduce highway gene ra ted n o i s e , the prob lem remains of how bes t to u t i l i s e t h i s i n f o r m a t i o n . U n f o r t u n a t e l y , because of i n f l a t e d l a nd v a l u e s , the c u r -r e n t t r e n d i s to b u i l d as c l o s e to- the highway, as p a s s i b l e . The immediate verge of a highway s hou l d not be p l a n t e d a s , i n • t h i s l o c a t i o n , t r e e s c o u l d r e p r e s e n t a t r a f f i c h a z a r d . These two f a c t s l i m i t the- use of t r e e s to a rea s where a l a r g e r i g h t of way a d j o i n s the h ighway, or ' to r u r a l a rea s where n o i s e i s not such a p r ob l em. F i r s t l y then we have to adopt a more p o s i t i v e approach to highway p l a n n i n g . We can b u i l d r e s i d e n t i a l a rea s next to f r eeway s but the env i r onment we c r e a t e i s not the b e s t . C o n v e r s e l y we can r e s t r i c t r e s i d e n t i a l a rea s to a s e t d i s t a n c e away f rom highways such t h a t n o i s e i s not a p r ob l em. The t h i r d a l t e r n a t i v e i s to p l a n t , ( p r o v i d i n g a ready made t r e e s c r e e n does not e x i s t ) , t r e e s to a s u f f i c i e n t w i d t h such t h a t t r a f f i c n o i s e l e v e l s a re a c c e p t a b l e . A l l too o f t e n d u r i n g highway c o n s t r u c t i o n t r e e s are c l e a r e d from the r i g h t of way to a d i s t a n c e of many f e e t f rom the highway edge. L e f t s t a n d i n g , these t r e e s c o u l d s i g n i f i c n a t l y reduce highway gene ra ted n o i s e . A p a r t from the n o i s e f a c t o r s , b e l t s of t r e e s a l o n g s i d e urban f r eeway s would p r o v i d e much needed r e c r e a t i o n a l a rea s and would l e a d to more a e s t h e t i c h ighways and c i t i e s . 7.5 R e c r e a t i o n and Park Des ign L i t t l e , i f a n y t h i n g , has been w r i t t e n on the t o p i c o f n o i s e abatement i n r e c r e a t i o n a l a r e a s . T h e r e f o r e , a l l i t ems sugges ted i n t h i s s e c t i o n a re based on p e r s o n a l o b s e r v a t i o n s and i d e a s . ' One of the most dominant f e a t u r e s of Nor th Amer ican l i f e i s the motor c a r . Peop le l a v i s h G o d - l i k e a f f e c t i o n on t he se machines and use them f o r a v a r i e t y o f p u r p o s e s . C u r r e n t l y more and more peop le are u s i n g the motor c a r f o r t h e i r v a c a t i o n s and r e c e n t y e a r s have seen a l a r g e i n c r e a s e i n the numbers of campers and t r a i l e r s on the roads of t h i s P r o v i n c e . A l l t h i s m o b i l i t y has c r e a t e d a demand f p r a p a r t i c u l a r t ype of r e c r e a t i o n f a c i l i t y - the o v e r n i g h t campground. The P r o v i n c i a l Government, i n one of i t s more e n l i g h t e n e d programmes, has c o n s t r u c t e d a network of t he se campgrounds t h r oughou t the p r o v i n c e . The Department of C o n s e r v a t i o n and R e c r e a t i o n has p r o v i d e d over 109 campgrounds w i t h from between 4 and 303 u n i t s i n e a c h . A p a r t f rom t h i s , p r i v a t e e n t e r p r i s e has p r o v i d e d many more campgrounds. As h ighways a re a major s ou r ce of n o i s e and one wh ich t r e e s can a t t e n u a t e , and as the m a j o r i t y of t he se campgrounds a re l o c a t e d near to the h i ghway, the r e s u l t s of t h i s s tudy s hou ld be of p a r t i c u l a r i n t e r e s t to the d e s i g n e r s and o p e r a t o r s of r o a d s i d e campgrounds i n the l ower ma in l and r e g i o n of • B r i t i s h C o l u m b i a . ' F r e q u e n t l y t he se c a m p s i t e s a re a d v e r t i s e d f o r t h e i r q u i e t n e s s - " S l e e p o f f the h ighway" be ing a f a v o u r i t e s l o g a n . J u d i c i o u s p l a n n i n g and d e s i g n of the campgrounds c o u l d p r o v i d e f o r a b e l t of t rees* of the. d e s i r e d w i d t h be ing m a i n t a i n e d between the highway and the campground u n i t s . W i t h i n a r e c r e a t i o n a l a rea t r e e s c o u l d be used to p r o v i d e both a v i s u a l and n o i s e b a r r i e r between a c t i v e and p a s s i v e a r e a s . 7.6 Urban Des i gn I t i s d i f f i c u l t to i s o l a t e t h i s s e c t i o n f rom two p r e v i o u s s e c t i o n s d i s c u s s e d i n . t h i s c h a p t e r , as they a re the p r i m a r y s ou r ce s of n o i s e i n urban a r e a s . However, B o n v a l l e t ( 1 9 5 1 ) , has produced i n f o r m a t i o n on n o i s e s i n r e s i d e n t i a l a rea s wh ich both i n c l u d e and e x c l u d e highway and i n d u s t r i a l n o i s e . The r e s u l t s a re r ep roduced i n F i g u r e 21 . A l t h o u g h the n o i s e l e v e l s are not e x c e s s i v e l y h i g h , i t i s i n t e r e s t i n g to note t h a t they peak between 0 and 250 c y c l e s per second - the range of f r e q u e n c i e s be s t a t t e n u a t e d by t r e e s t a n d s . T IHUfK OR HtXrSTRl BACKCROU ONtOEMT M . X > *A?*;E Of AVERAGE LEVELS fOn RESOE«<IAL AREAS WITH T R A F F C OR INDUS! | RIAL t IACKCR CHJNOS JL. W G K T " RANGE Of AVERAGE L E V E L S " V \ FOR fE51DENTIA1. AR£>S W T T M \ _ . . f Hjrrwuiiiiiai r • Lrvr.itrthr^ MUM LEVELS FOR > -N1CKT CC RE SIM WOITI T1AL. MS IN AREA OVCT- 0 SO T, CO ISO ZOO 500 400 600 BOO 1200 1600 2*00 4S00 AU. SO 100 ISO BOO SOO 400 600 600 1200 1600 Z400 S2C0 4300 OS 0CT4VE BANDS, CPS . FIG.21. Average levels of residential area noise. The upper two curves define residential area noise conditions which are intense due to nearby industrial or traffic noise. The area below is for more quiet conditions where the background is more or less unidentifiable. The lowest curve indicates minimum levels at night. s ( A f t e r B o n v a l l e t , 1951) U n t i l c i t i e s become more open i n t h e i r g e n e r a l l a y o u t s , i t i s not env i s a ged t h a t t r e e s have a sound a t t e n u a t i n g r o l e , t o p l a y , e x cep t i n the a rea s around f r e e -ways as has a l r e a d y been m e n t i o n e d . With more open p l a n -n i n g , . t h e scope f o r t r e e s i s enhanced and l a r g e f o r e s t e d a rea s w i t h i n a c i t y become a d i s t i n c t p o s s i b i l i t y . Who c o u l d have f o r e s e e n , s e ven t y y e a r s ago, the p l a c e t h a t S t a n l e y Park ho ld s i n the esteem of V a n c o u v e r i t e s . How-e v e r , we do not seem t o have l e a r n t by t h i s example . The q u i e t r e t r e a t t h a t S t a n l e y Park has become, r i g h t i n the h e a r t of a downtown a r e a , s hou ld be d u p l i c a t e d i n o t h e r a rea s o f the c i t y and i n o t h e r c i t i e s . The e f f e c t on the p h y s i c a l and p s y c h o l o g i c a l h e a l t h of a c i t y ' s i n h a b i t a n t s must be enormous i f t hey have a rea s where they can escape to and r e c u p e r a t e . Chapte r V I I I SUGGESTIONS FOR FUTURE WORK AND CONCLUSIONS 8.1 S ugge s t i on s f o r Fu tu re Work 8.1.1 Managed s t a n d s . I t became a p p a r e n t , a f t e r the c o m p l e t i o n of w i n t e r da ta c o l l e c t i o n , t h a t the e x p e r i m e n t a l des i gn - was not go ing to y i e l d i n f o r m a t i o n on which s tand f a c t o r s cause sound a t t e n u a t i o n . I t i s sugges ted t h a t t h i s f a c t can be remedied by the a d o p t i o n of the f o l l o w i n g p r o c e d u r e . Stands would be s e l e c t e d w i t h i n one s p e c i e s or s p e c i e s c o m b i n a t i o n , on the b a s i s of even g r o w t h , t h r o u g h -out a wide age r ange . These s tands would have v a r i o u s pa rameter s measured and then the sound measurements would be done. Th i s would g i v e base l i n e sound p r e s s u r e l e v e l v a l u e s w i t h a l l s tands i n t h e i r n a t u r a l c o n d i t i o n . F o l -l o w i n g t h i s v a r i o u s management i n p u t s would be made, sound p r e s s u r e l e v e l measurements be ing made a f t e r e a ch . A n t i c i -pated management p r ocedu re s are as f o l l o w s : 1 . Remove, dry and weigh, the ground v e g e t a t i o n . 2. Remove, dry and weigh logs- and l i t t e r on the f o r e s t f l o o r . 3 . Brash the trees to a height of 6 f e e t . 5 . Prune the t r e e s t o a h e i g h t of 18 f e e t . 6 . F e l l and remove 20% (by b a s a l a r e a or stems per a c r e ) o f t r e e s . 7 . F e l l and remove 20% (by b a s a l a r e a or stems per a c r e ) o f o r i g i n a l t r e e s . 8 . F e l l and remove 20% (by b a s a l a r e a or stems . per a c r e ) of o r i g i n a l t r e e s . 9 . F e l l and remove 20% (by b a s a l a r e a or stems per a c r e ) o f o r i g i n a l t r e e s . By compar i son of the sound p r e s s u r e l e v e l s measured a f t e r each s t e p , f o r the t o t a l of ( s ay ) 10 s t a n d s , the a t t e n u a t i o n caused by each s t ep s hou l d become a p p a r e n t . Th i s s h o u l d e l i m i n a t e some, i f not a l l , of the problems caused by n a t u r a l v a r i a t i o n w i t h i n a s t a n d . 8 .1 .2 A r t i f i c i a l s t a n d s . Th i s i s an a l t e r n a t i v e method to d i s c o v e r , the s t and f a c t o r or f a c t o r s c a u s i n g sound a t t e n u a t i o n , and was sug -g e s t e d by Mr. J . W a l t e r s , D i r e c t o r of the U n i v e r s i t y o f B r i t i s h Co lumb ia Research F o r e s t . In t h i s t e c h n i q u e young t r e e s would be f e l l e d and f i r m l y f i x e d to wooden bases or b u c k e t s ' f i l l e d w i t h s o i l or c o n c r e t e . These t r e e s would then be a r r a n g e d , on a s u i t a b l e a rea of f l a t g r ound , i n a v a r i e t y of d e n s i t i e s and s p a c i n g p a t t e r n s and sound p r e s -su re l e v e l measurements t a k e n . V a r i o u s t ype s of ground cove r c o u l d a l s o be t e s t e d , e i t h e r by c u t t i n g and p l a c i n g bushes e t c . between the t r e e s , or by p l a c i n g the t r e e s on s u i t a b l e a reas of v e g e t a t i o n . Once aga i n the t r e e s c o u l d be b ra shed and pruned as d e s c r i b e d i n the p r e v i o u s s e c t i o n . 8 .1 .3 To t e s t the t heo r y of d i m i n i s h i n g a t t e n u a t i o n  c o e f f i c i e n t s and the i n v e r s e square l aw . These hypotheses c o u l d be t e s t e d u s i ng e i t h e r of the two new de s i g n s o u t l i n e d above , or by the one used i n t h i s s t u d y . Sound p r e s s u r e l e v e l measurements wouTd- be made a t 10 f e e t i n t e r v a l s i n s t e a d of 50 f e e t . I f the h y p o t h e s i s o u t l i n e d i n Chap te r VI r e g a r d i n g the l ower a t t e n u a t i o n c o e f f i c i e n t s a t the l o n g e r d i s t a n c e s i s t r u e , then t h e r e s h o u l d e x i s t a c r i t i c a l d i s t a n c e w i t h i n each s t a n d , a f t e r wh ich the r e f l e c t e d waves g i v e l a r g e r than expec ted sound p r e s s u r e l e v e l v a l u e s . The i n v e r s e square law h y p o t h e s i s s u f f e r e d f rom i n s u f f i c i e n t d a t a and c o u l d not be e f f e c t i v e l y t e s t e d . A 10 f e e t i n t e r v a l s h o u l d remedy t h i s g i v i n g 15 da ta c o l l e c -t i o n p o i n t s ove r 150 f e e t . In t h e o r y the se two hypotheses c o n t r a d i c t each o t h e r , and p r o v i n g one s hou ld d i s p r o v e the o t h e r 8 .1 .4 The h e i g h t of the sound s o u r c e . In t h i s s t udy the sound s ou r ce was a t a c o n s t a n t h e i g h t o f 2 f e e t 6 i n che s above the g round . In the case o f , a highway c o n s t r u c t e d on a f i l l , the sound sou rce would o r i g i n a t e from a h e i g h t c o n s i d e r a b l y g r e a t e r than 2 f e e t 6 i n c h e s . The e f f e c t of the h e i g h t of- the sound sou rce may have c o n s i d e r a b l e impo r t ance and would be r e l a t i v e l y s i m p l e to i n v e s t i g a t e . 8 .1 .5 Other f a c t o r s . As was p r e v i o u s l y ment ioned i n Chap te r VI the s tand f a c t o r c a u s i n g a t t e n u a t i o n may not have been i n v e s t i g a t e d a t a l l . I t i s s ugges ted t h a t i n t o a l l f u t u r e e x p e r i m e n t a l d e s i g n s the f o l l o w i n g f a c t o r s be i n c o r p o r a t e d . 1 . Biomass o f ground v e g e t a t i o n . . 2. Needle s i z e - e s t i m a t e o f s u r f a c e a r e a . 03. L e a f s i z e - e s t i m a t e of s u r f a c e a r e a . 4. Biomass o f l o g s and l i t t e r on- f o r e s t f l o o r . - -5. Branch form - a n g l e formed w i t h the t r u n k . 8.1.6 White c a rd t e c h n i q u e f o r e s t i m a t i n g the  ground v e g e t a t i o n . To t e s t t h i s t e c h n i q u e as o u t l i n e d i n Chap te r VI would be an i n t e r e s t i n g s i d e l i n e to any f u t u r e s t u d y . I t would a lmos t c e r t a i n l y , i f s u c c e s s f u l , be e a s i e r to pe r f o rm than measu r i ng the biomass of the ground v e g e t a t i o n . A l s o of use would be an i n v e s t i g a t i o n of a . p o s s i b l e c o r r e l a t i o n between, biomass of the v e g e t a t i o n and the a rea o f c a rd c o v e r e d . 8 .1 .7 Shrub s p e c i e s . A programme to t e s t the a t t e n u a t i n g a b i l i t i e s of v a r i o u s t ype s of shrub s p e c i e s commonly, used i n l a n d s c a p e a r c h i t e c t u r e s h o u l d be i n s t i g a t e d . I t i s e n v i s a g e d t h a t t h i s would be done i n c o - o p e r a t i o n w i t h the Department of . P l a n t S c i e n c e a t the U n i v e r s i t y of B r i t i s h C o l u m b i a . A c o n c l u s i o n to a t h e s i s must a lways be w r i t t e n and read b e a r i n g i n mind the o r i g i n a l o b j e c t i v e s . Hence, the o b j e c t i v e s o u t l i n e d i n Chapte r I w i l l be r e s t a t e d . To i n v e s t i g a t e and quantify the sound attenua-tion at various frequencies' of screens of trees compos ed of d i f f e r e n t species; and to attempt to c o r r e l a t e this attenuation with various mea-sured c h a r a c t e r i s t i c s .of the tree stand and its associated ground vegetation. B a s i c a l l y t h i s t h e s i s has been s u c c e s s f u l i n one o b j e c t i v e and u n s u c c e s s f u l i n the o t h e r . I n f o r m a t i o n i s p r e s e n t e d i n t h i s t h e s i s on the sound a t t e n u a t i n g a b i l i t i e s of e i g h -teen t r e e s tands composed of f o u r s p e c i e s . These r e s u l t s w i l l h o p e f u l l y have i m p l i c a t i o n s to h ighway, i n d u s t r i a l , u r b a n , and park and r e c r e a t i o n de s i g n i n the l o w e r ma i n -l a nd a rea of B r i t i s h C o l u m b i a . I n f o r m a t i o n was p r e s e n t e d on an i n d i v i d u a l s t and b a s i s and as mean v a l u e s f o r each s p e c i e s . The e f f e c t of two d i f f e r e n t seasons was i n v e s -t i g a t e d and shown to have l i t t l e i f any e f f e c t . I t was a l s o shown t h a t s t ands r e a c t e d i n d e p e n d a n t l y to the e f f e c t o f a* change i n s ea son . I n s u f f i c i e n t d i s t a n c e s were measured to enab l e the i n v e r s e squa re law to be p r o p e r l y t e s t e d , but recom-mendat ions were made as. to how t h i s may.be done a t some f u t u r e t i m e . The ' S ' shaped cu r ve o f sound a t t e n u a t i o n p l o t t e d a g a i n s t f r e q u e n c y of sound was found i n t h i s s tudy and c o n f i r m s the r e s u l t s of p r e v i o u s w o r k e r s . Th-e s t udy f a i l e d i n i t s second major o b j e c t i v e , t h a t of a s c e r t a i n i n g what causes t r e e s to a t t e n u a t e sound. V a r i o u s f a c t o r s were i n v e s t i g a t e d but no p a t t e r n of c o r r e -l a t i o n w i t h sound a t t e n u a t i o n was o b s e r v e d . Recommendations were made f o r f u t u r e t e c h n i q u e s to d i s c o ' v e r t h i s f a c t o r and o t h e r c h a r a c t e r i s t i c s deemed wor th i n v e s t i g a t i n g . A p e c u l i a r i t y was found i n the a t t e n u a t i o n c o e f f i c -i e n t s a t v a r y i n g d i s t a n c e s i n t h a t they d i d not remain c o n s t a n t . An h y p o t h e s i s s u g g e s t i n g the reason f o r t h i s was p r e s e n t e d as was a method f o r t e s t i n g i t . APPENDIX 1 Map Showing L o c a t i o n o f the Tree Stand's APPENDIX 2 Stand I n f o r m a t i o n f o r - the Four S p e c i e s D 2 = D.3 = 50 f t . x 30 f t . b l o c k 1 0 0 f t . x 30 f t . b l o c k 1 5 0 f t . x 30 f t . b l o c k Numbers i n p a r en the se s () a re summer v a l u e s when they d i f f e r f rom the w i n t e r v a l u e s . e The age and number of stems per a c r e remain c o n s t a n t f o r D o u g l a s - f i r as those s tands were a r t i f i c i a l l y c r e a t e d s p a c i ng t r i a l s . -1.09-STAND- I STAND II STAND I I I STAND IV D 2 D 3 Di D 2 D 3 D-! D 2 D 3 D 2 D 3 Ba sa l A rea i n s q . f t / a c r e 130.8 261 .4 392.1 95.8 191.6 28.7 .4 40 .7 81 .4 12 2.1 33.4 66.8 100.2 Number of S tems/Acre 3822 3822 3822 1163 1163 1163 476 476 476 276 276 276 H e i g h t o f the f i r s t b ranch i n f t . 0.5 0.5 0.6 0.8 H e i g h t t o the f i r s t l i v e b ranch i n f t . 8.3 5.4 2.4 0.8 Length o f Crown i n f t . 15.2 21.1 21.8 23.1 H e i g h t of ground v e g e t a t i o n i n f t . 0.0 (3 -6 ) 0.2 (2-1 ) 8.7 ( 7 -6 ) 8.6. (7 -8 ) Age 1 2 12 1 2 1 2 Average D i amete r a t B r e a s t H e i g h t i n i n c h e s . 2.5 3.9 4.0 4.6 o I STAND I STAND II STAND I I I STAND IV STAND V D 2 D 3 • Da D 3 D i D 2 D 3 Di D 2 D 3 " Di D 2 D 3 Ba sa l A rea i n s q . f t . / a c r e 8.2.8 212.4 357.3 .1 64.1 342.1 536.7 196.1 497 .2 738.3 56.9 382.8 669 .9 1 27.1 357 .4 955.6 Number o f s t e m s / a c r e 987 973 1094 450 503 494 - 871 682 610 319 3 63 348 407 " 465 484 H e i g h t - t o the f i r s t b ranch 4.9 1 .8 8.9 7.4 9.8 H e i g h t t o the f i r s t l i v e b ranch 53. 5 67.9 67.9 45.3 7 2.8 Length o f Crown i n f t . 22.6 28.6 21.0. 44.0 38.7 H e i g h t o'f Ground Vege-t a t i o n i n f t . 1 . 3 ( 1 . 0 ) 0.6 (0 .9 ) 0.5 ( 0 .8 ) 2 . 3 ( 6 . 2 ) 2.3 ( 2 .0 ) Age 36 39 40 . . . . . . . 44 55 . Average Diam. a t B r e a s t He i gh t i n i n c h e s 4.2 • 7.8 6.0 5.7 7.0 STAND INFORMATION FOR ALDER STAND I • STAND II STAND I I I STAND IV STAND V D 2 D3 Dr D 2 D 3 Di D 2 J D 3 D: D 2 D 3 Di • D 2 D 3 • -Ba sa l A rea i n s q . f t . / a c r e 20.9 34.4 55.0 23.2 46.4 62.7 20.1 51 .4 88.0 343.7 452.4 1017.0 108.1 214.8 318.2 Number of s terns/ a c r e 3425 4385 6040 2369 2456 2573 1 365 1350 1278 494 624 610 407 450 426 H e i g h t to the f i r s t b ranch i n f e e t 4.9 5.7 6.2 25.0 7.3 H e i g h t to the f i r s t l i v e b rnach i n f e e t . -; 20.0 (0 .0 ) 8.5 (11 .5) 11.0 (19 .2 ) 15.8 (29 .3 ) 10.4 0,9.6) Length o f Crown i n f e e t . 12.1 (0 .0 ) 37.5 (34.5 ) 48.2 (40 .0 ) 65.0 (51 .5) 47.4 (48 .2 ) H e i g h t o f Ground V e g e t a t i o n i n f t . 5.1 (4 .3 ) 4.2 ( 4.1 ) 5.3 ( 3.4) 8.9 (11 .8 ) 5.9 ( 5.8) Age 14 20 32 35 , Average Di am . a t B r e a s t H e i g h t i n i n c h e s 14 1 .3 1 .6 11.2 7 . 0 . r o i STAND I STAND II STAND I I I STAND IV Di D 2 D 3 Dr D 2 D 3 Di D 2 D 3 : .D r D 2 D 3 Ba sa l A rea i ir sq . f t . / a c r e ' • 6.1 12.2 18.3 41 .2 69.5 91 .6 31 .4 54.5 80 .8 46.2 89 .2 1 39 . 7 Number o f S tems/Acre 7638 7144 6321 2062 2018 2362 581 741 81 3 1919 1 655 1646 He i gh t to the f i r s t b ranch i n f e e t 3.3 16.4 6.2 14.1 H e i g h t to the f i r s t l i v e , b r anch i n f e e t 12 . 7 ( 0 . 0 ) 1 9 . 1 ( 0 . 0 ) 1 1 . 0 ( 0 . 0 ) 1 8 . 5 ( 0 . 0 ) Length o f Crown i n f e e t 17 . 7 ( 0 . 0 ) 2 0 . 6 ( 0 . 0 ) 4 8 . 2 ( 0 . 0 ) 29.7 ( 0 .0 ) H e i g h t o f ground v e g e t a t i o n i n f e e t 3 . 2 (3 .9 ) 4 . 1 ( 2 . 3 ) 5 . 3 ( 3 . 3 ) 3.0 ( 3 .9 ) Age 1 5 21 22 28 Average Diam. a t B r e a s t h e i g h t i n i n c h e s 0.9 .2.4 1.6 2.7 APPENDIX 3 Summer and W i n t e r C o r r e l a t i o n M a t r i c e s . X i • - B a s a l a r e a . x 2 -- Number of stems per a c r e . x 3 -- L e n g t h of c l e a r b o l e . x. -- He i gh t to the f i r s t 1 i v e branch . x 5 -- Length of l i v e c rown. x 6 -- H e i g h t of the ground v e g e t a t i o n . x 7 • - Average d i a m e t e r of the t r e e s a t b r e a s t h e i g h t . x 8 • - A g e . - . • Key to Y. Odd numbers a re s e t t i n g ' A 1 . Even numbers a re s e t t i n g ' C ' . I and 2 = 125 c y c l e s per second 3 and e 4 = 250 c y c l e s per second 5 and 6 = 500 c y c l e s per second 7 and 8•= 1000 c y c l e s per second 9 and 10 = 2000 c y c l e s per second I I and 12 = 4000 c y c l e s per second 13 and 14 = 8000 c y c l e s per second 15 and 16 = 12000 c y c l e s per second * R e l a t i o n s h i p c o r r e l a t e d s i g n i f i c a n t l y a t the 5% l e v e l . SUMMER CORRELATION MATRIX - DOUGLAS FIR X: x 2 x 3 X, x 5 x 6 x 7 X i + 1 .0000. x 2 +0 .6924. +1 .0000 x 3 -0 .6139 -0 .6385 + 1 .0000 x. +0 .7478 +0 .9283 -0 .8593 + 1 .0000 x 5 -0 . 6764 -0 .99 38 +0 .6668 -0 .9232 + 1 .0000 x 6 -0 . 7208 -0 .7571 +0 .8116 -0 .9175 +0 .7194 + 1 .0000 • x 7 -0 . 6756 -0 .9738 +0 .7425 -0 .9362 +0 .9913 +0 . 7228 + 1 .0000 Y i +0 .1038 -0 . 2771 +0 .2718 -0 .2742 +0 .3001 +0 .1680 +0 .3205 Y 2 +0 .1125 -0 . 3250 +0 .5099 -0 .4146 +0 .3571 +0 .3285 +0 .4064 Y 3 +0 .1107 -0 .2671 +0 .5181 -0 .3741 +0 .3073 + 0 .2841 +0 . 3677 Y 4 +0 .1429 -0 .2190 +0 .4191 -0 .3496 +0 . 2569 +0 .3866 +0 .3203 Y 5 +0 .1682 -0 . 4093 ' +0 .1729 -0 .2546 +0 .4671 -0 .0528 + 0 .4848 Y 6 +0 .1874 -0 .3837 +0 .2248 -0 .2689 +0 .4397 -0 .0072 +0 .4647 Y 7 +0 .4617 +0 .0445 -0 .1975 +0 .1676 -0 .015 2 -0 .3114 -0 .01 67 Ye +0 .4911 +0 .0467 -0 .2100 +0 .1747 -0 .0180 -0 .3194 -0 .0210 Y 9 -0 .2022 -0 .1032 +0 .5712 -0 .3015 +0 .1466 +0 .2786 +0 .2299 Y io -0 . 2994 -0 .2983 +0 .6057* -0 .433T +0 .3425 +0 .3433 + 0 .41 26 Y i i +0 .2287 -0 .0131 +0 .3054 -0 . 1 584 +0 .0196 +0 . 2207 +0 .0580 Y l 2 +0 .1898 -0 .0578 +0 .3429 -0 .2035 + 0 .0 649 +0 .2576 + 0 . 1 039 ' Y l 3 -0 .0650* -0 .3440 +0 .7372* -0^ .5640 : +0 .3611 ' +0 .5901 +0 .4262 Y n , +0 .0541 -0 .3179 +0 .6165* -0 .4883 ;+o .3330 +0 .4960 + 0 .3851 Y l 5 +0 .0281 -0 .1964 +0 .3789 -0 .2974 + 0 .2081 +0 .2944 + 0 .241 5 Y l 6 -0 . 3357 -0 .5947 +0 .2890 -0 .4683 + 0 .6188* +0 .2424 + 0 .61 30 x 2 x 3 x 4 x 5 X 6 x 7 + 1 .0000 x 2 + 0 . 6924 + 1 .0000 x 3 - 0 .6134 - 0 .6385 + 1 .0000 x 4 + 0 .7478 + 0 .9 282 - 0 . 8593 + 1 .0000 X 5 - 0 .6764 - 0 .9938 + 0 .6668 - 0 .9232 + 1 . 0000 x 6 . - 0 .6524 - 0 .5889 + 0 .81 38 - 0 .821 2 + 0 . 5501 + 1 . 0 0 0 0 x 7 - 0 . 6756 - 0 .9738 + 0 .7425 - 0 .9362 + 0 .991 3 + 0 . 5 683 + 1 . 0 000 Y i + 0 .1219 ^0 .1263 + 0 .4370 . - 0 .3185 + 0 .1139 + 0 . 5114 + 0 . 1459 Y 2 + 0 .2906 - 0 .1159 + 0 .3640 - 0 .271 5 + 0 . 1055 + 0 . 4248 + 0 .131 2 Y 3 + 0 . 2263 - 0 .1915 + 0 .4107 - 0 .2979 + 0 . 2134 + 0 . 2848 + 0 .2571 Y - + 0 . 2209 - 0 .1934 + 0 .4055 - 0 .3006 + 0 . 2120 + 0 . 2975 + 0 . 2530 Y 5 . +0 . 181 7 -0 . 4264 - 0 .0405 - 0 .2123 + 0 . 4393 - 0 . 1 61 9 + 0 . 4036 Y 6 + 0 .2191 - 0 . 3 9 3 5 ' + 0 . 0875 - 0 .2309 + 0 . 4284 - 0 . 1474 + 0 . 4238 Y 7 -.0 . 0153 - 0 .3826 - 0 .0525 - 0 .1801 + 0 .3957 - 0 . 1 706 + 0 . 3627 Ye + 0 .1129 . - 0 .3227 + 0 . 0203 - 0 .1897 + 0 . 3307 ' - 0 . 0 593 : +o . 3085 Y 9 +0 .061 3 + 0 .21 59 - 0 .4192 + 0 .2550 - 0 .2847 - 0 . 0287 - 0 . 3554 Y i o +0 .1 356 + 0 .1667 -0 . 3823 + 0 .2066 - 0 .2357 +0 . 0053 - 0 . 3066 Y i i + 0 . 5783 + 0 .1387 - 0 .5746 + 0 . 4005 - 0 . 1240 - 0 . 6 6 6 2 * - 0 . 1 696 Y l 2 + 0 .5134 + 0 .0692 - 0 .5341 + 0 .3462 - 0 . 0486 - 0 . 6 6 4 5 * - 0 . 0922 Y l 3 + 0 .4741 + 0 .2587 - 0 .2941 + 0 .3258 - 0 .2431 - 0 . 3650 - 0 . 2446 Y11 + 0 . 6 4 3 0 * + 0 .2322 -0 .3712 + 0 .3144 - 0 . 2440 - 0 . 2 954 - 0 . 2733 Y i s - 0 .3763 + 0 .2131 - 0 .0223 + 0 .1750 - 0 . 1840 - 0 .1621 - 0 . 1498 Y l 6 +.0 . 4991 + 0 .391 6 - 0 .0218 + 0 . 2363 - 0 . 3954 + 0 . 0 424 - 0 . 3647 X i - X 2 x 3 x - x 5 X 6 x 8 . x 7 X i + 1 . 0 0 0 0 x 2 - 0 . 2 2 6 0 + 1 . 0 0 0 0 x 3 +0 . 2 6 1 6 - 0 . 1 5 1 6 + 1 . 0 0 0 0 X . +0 . 2 2 8 5 - 0 . 0 6 5 1 +0 . 1 3 8 4 + 1 . 0 0 0 0 x 5 +0 . 1 0 3 5 - 0 . 7 987 +0 . 2 8 9 9 - 0 . 2 9 1 5 + 1 . 0 0 0 0 X 6 +0 . 0 4 1 6 - 0 . 4 3 2 1 +0 . 4 8 6 6 - 0 . 3 5 6 6 + 0 . 8 6 0 9 + 1 . 0 0 0 0 X r + 0 . 2 6 2 6 - 0 . 5 9 0 6 +0 . 6 6 0 2 +0 . 3 8 1 3 +0 . 6 8 4 9 + 0 . 7 0 4 9 + 1 . 0 0 0 0 x 8 +0 . 7 1 1 9 - 0 . 7 4 0 0 +0 . 1 9 2 8 +0 . 3 3 2 1 + 0 . 5 0 8 1 + 0 . 2 1 62 + 0 . 5 5 3 0 + 1 . 0 0 0 0 +0 . 7 3 1 1 * +0 . 0 2 3 4 +0 . 6 0 6 1 * + 0 . 1 5 9 2 + 0 . 1 2 1 1 - + 0 . 2 6 2 9 +0 . 4 1 1 9 + 0 . 3 9 8 3 Y 2 +0 . 7 4 2 5 * + 0 . 0 2 1 6 +0 . 5 4 9 0 * - 0 . 0 0 4 6 + 0 . 0 5 6 7 + 0 . 1 3 3 8 + 0 . 2 0 5 0 +0 . 3 9 8 6 Y 3 + 0 . 4 8 5 4 +0 . 2 0 3 1 +0 . 0 2 5 0 - 0 . 1 2 5 5 - 0 . 2 0 6 7 - 0 . 1 7 0 6 - 0 . 2 3 8 5 + 0 . 1 5 9 8 U + 0 . 4 7 8 2 +0 . 0 5 4 8 + 0 . 1 4 1 9 - 0 . 1 0 2 0 - 0 . 0 3 4 8 - 0 . 0 1 44 - 0 . 0 5 4 9 + 0 . 2 2 5 8 Y 5 +0 . 6 1 3 8 * - 0 . 1 2 1 3 - 0 . 2 0 7 5 - 0 . 1 7 6 2 + 0 . 0 9 . 5 3 - 0 . 0 6 2 9 - 0 . 1 5 4 5 . • + 0 . 5 1 7 1 Ye +0 . 6 . 5 3 8 * +0 . 0 4 1 2 - 0 . 2 7 7 1 * - 0 . 0 7 4 0 - 0 . 1 0 5 9 - 0 . 2 3 4 4 - 0 . 2 6 6 0 + 0 . 4 1 8 3 Y 7 +0 . 5 9 3 7 * +0 . 0 9 2 7 +0 . 3 0 4 2 - 0 . 1 4 2 3 + 0 . 0 8 7 7 + 0 . 2 7 57 + 0 . 1 4 7 5 + 0 . 2 0 4 0 Y 8 + 0 . 6 5 2 0 * +0 . 1 1 4 8 +0 . 2 9 5 1 +0 . 0 0 1 4 + 0 . 0 4 3 5 + 0 . 2 3 8 5 +0 . 2 0 3 3 + 0 . 2 4 1 7 Y 9 + 0 . 1 2 3 0 +0 . 1 7 7 4 +0 . 4 2 2 0 +0 . 1 666 . - 0 .1 2 3 9 • - 0 . 0 7 0 5 + 0 . 1 1 6 2 - 0 . 0 0 8 3 Y i o +0 . 1 6 5 7 +0 . 1 5 3 8 +0 . 4 6 4 8 +0 . 1 9 5 5 - 0 . 1 1 7 5 - 0 . 0 5 4 3 + 0 . 1 5 4 6 +0 . 0 2 1 8 Y n +0 . 2 3 2 8 +0 . 1 2 8 2 +0 . 5 8 6 9 * - 0 . 0 0 9 7 - 0 . - 0 3 0 - 0 . 0 2 3 2 + 0 . 0 7 4 4 + 0 . 1 0 5 7 Y12 +0 . 1 7 3 4 +0 . 1 2 6 3 +0 . 5 6 9 5 * + 0 . 0 3 1 4 . . . - 0 . 1 2 8 0 - 0 . 0 5 6 8 + 0 . 0 6 6 9 + 0 . 0 7 2 4 Y 1 3 - 0 . 2 7 2 7 +0 . 2 7 5 6 +0 . 6 4 1 5 * - 0 . 0 6 3 9 - 0 . 0 9 0 7 + 0 .1 1 60 + 0 . 1 2 3 2 - 0 . 3 3 0 0 * +0 . 0 239 +0 . 0 7 1 9 +0 . 4 3 5 3 - 0 . 2 3 5 6 - 0 . 1 0 9 1 - 0 . 1 2 6 5 - 0 . 1 6 1 7 - 0 . 1 7 7 4 Y l S - 0 . 0 9 6 6 - 0 . 0 5 9 3 +0 . 4 2 1 0 +0 . 0 7 1 5 - 0 .11-14 - 0 . 0 9 2 5 + 0 . 0 4 8 4 - 0 . 11 4 0 Y 1 6 : +0 . 0 0 3 9 - 0 . 1 1 4 2 - 0 . 0 3 9 0 - 0 . 4 5 3 2 +0 . 0 0 0 7 - 0 . 1 6 2 5 - 0 . 3 8 1 4 - 0 . 0 3 6 4 X r x 2 x 3 X- X 5 X 6 X 8 ' X y Xi + 1 . 0000 • X2- -0. 2260 + 1 .0000 x 3 + 0. 261 6 -0 .1516 + 1 .0000 x 4 +0. 2285 -0 .0651 +0 .1384 + 1 .0000 X 5 + 0. 1035 • -0 .7987 + 0 . 2899 -0 .2915 + 1 .0000 x 6 + 0. 2309 +0 . 2057 +0 . 5270 +0 .4444 -0 . 5034 + 1 .0000 Xy +0. 2626 -0 . 5906 +0 .6602 +0 .3813 +0 . 6849 -0 .0327 + 1 .0000 X 8 +0. 7119 -0 .7400 +0 .1928 +0 .3321 +0 . 5081' -0 .0203 + 0 .5530 + 1 .0000 Yi + 0. 3094 ' +0 .1749 +0 .0462 -0 . 2402 + 0 . 1 229 -0 . 2609 +0 .0523- + 0 .0649 Y2 + 0. 7351 * -0 .3331 +0 . 2433 -0 .2257* + 0 .4477 -0 .1 350 + 0 .2857 + 0 .6607* Y 3 + 0. 4507 -0 .3077 + 0 .0313 -0 .0675 + 0 .4299 -0 . 3947 +0 .3441 +0 .5276* Y 4 +0. 2672 -0 .4746 +0 .4439 -0 .1317 +0 .6666* -0 .2110 + 0 .6096 + 0 .5360 Y 5 +0. 1852 +0 .4763 -0 .5646* + 0 .2337 -0 .7202* + 0 .1813 -0 .6397 -0 .0511* Y 6 +0. 1838 + 0 . 2697 -0 .5124* +0 .3358 -0 .5984* + 0 .2166 -0 .5025 + 0 .1355* Yy + 0. 3511 -0 .1377 +0 .3515 + 0 .0196 +0 . 2376 + 0 . 1 505 +0 .2904 + 0 .3863 Ye +0. 6401* -0 .0453 + 0 .3661 +0 .0137 +0 .1738 + 0 .1844 +0 .2533 + 0 .4223 Y 9 -0. 2026 +0 .3663 +0 .5515* -0 .1192 -0 .0519 • +0 .2851 + 0 .151 5 -0 .3872* Yio -0. 1294 +0 .3597 +0 .4993 -0 .2769 -0 .0470 + 0 .2674 +0 .0298 -0 .3654 Y n + 0. 1 707 +0 .1603 + 0 .4780 -0 .0686 -0 .0661 .+ 0 .4348 + 0 .061 9 + 0 .0224 Y12 + 0. 149 7 +0 .0503 + 0 .5288* + 0 .0250 + 0 .0505 + 0 . 3853 + 0 .2272 + 0 .1371 Y l 3 + 0. 1 280 + 0 .1438 +0 .2986 -0 .1144 +0 .1042 -0 .011 0 + 0 .1826 + 0 .0768 Y i . + 0. 5778* -0 .1729 +0 .4983 -0 .1719 *0 .3403 + 0 . 1 335 + 0 .3257 + 0 .4678 Y 1 5 - a . 521 6* -0 .0911 + 0 .3969* -0 .1648 + 0 .01 02 + 0 .3393 + 0 .0242 -0 .3719 Y l 6 + 0. 4981 -0 .5381 +0 .5365* -0 .2065 + 0 .5874* + 0 .1662 + 0 .4275 + 0 .6286* X i X 2 x 3 x . x 5 x 6 X 8 x 7 X i + 1 . 0000 x 2 - 0 . 4694 + 1 .0000 x 3 + 0 . 8227 - 0 .4858 + 1 . 0000 x - + 0 . T7 7 2 + 0 . 5228 +0 .2528 + 1 .0000 x 5 + 0 . 6278 - 0 .8927 +0 .7219 -0 .41 50 + 1 .0000 x 6 + 0 . 7692 - 0 . 3198 +0 .9044 + 0 .5678 + 0 . 4943 + 1 . 0000 Xy +0. 61 81 - 0 .8322 +0 .5857 -0 . 1853 + 0 . 7679 + 0 .5817 + 1 . 0000 X 8 +0. 7 3 37 - 0 .6860 +0 . 8425 + 0 . 0964 +0 . 7462 + 0 . 8398• + 0 . 8968 + 1 . 0000 • Y i +0. 7 5 1 2 * - 0 .5101 +0 . 5124 +0 .1044 + 0 . 4 9 3 8 * + 0 .6086 + 0 . 7 9 8 8 * + 0 . 7246 Y-2 + 0 . 3937 : - 0 . 4738 + 0 . 2625 - 0 .0530 + 0 . 3 6 7 0 * + 0 . 3675 + 0 . 7 6 4 6 * +0 .61 49 Y 3 + 0 . 4410 - 0 .2001 +0 .0846 - 0 .2457 + 0 . 2528 + 0 .0153- + 0 . 2609 + 0 .1136 Y„ +0. 07 24 - 0 . 3359 - 0 . 1 563 -0 .4408 0 . 2152 - 0 .1847 + 0 . 3750 + 0 . 1102 Y 5 - 0 . 1 186 +0 . 6 9 6 8 * - 0 .0796 +0 .4789 - 0 .4961 - 0 . 0309 - 0 .6475 ' - 0 . 4337 Y 6 - 0 . 1185 +0 . 7 4 8 3 * - 0 .1117 +0 .5260 -.0 .5281 - 0 .0245 - 0 . 6513 - 0 . 4532 Y 7 +0. 5844 - 0 .0028 +0 . 6095 + 0 . 6875 + 0 . 0969 +0 . 7 5 9 7 * + 0 . 2275 + 0 .492.4 Y 8 + 0 . 4673 - 0 .0189 +0 .5514 + 0 .6551 . +0 . 0820 + 0 . 7 1 5 0 * + 0 . 2384 + 0 .4928 Y 9 + 0 . •1-911 +0 . 2 8 7 9 ' + 0 . 1314 - +0 .7025 - 0 . 2849 + 0 .4079 - 0 . 0273 + 0 . 0753 Yio +0. 2785 + 0 . 1834 +0 . 2434 + 0 . 6 5 3 8 * - 0 .1417 + 0 . 4905 + 0 .0887 + 0 . 1923 Y n +0. 3309 + 0 .4321 + 0 . 1848 + 0 . 7 0 3 3 * - 0 . 2678 + 0 .4100 - 0 . 1233 + 0 . 0095 Y l 2 + 0 . 2673 +0 .2896 + 0 .1790 + 0 . 5 7 5 1 * -,0 . 1843 + 0 . 3666 -0 .0579 + 0 . 0324 Y l 3 +0. 1 693 +0 .4427 • +0 .1 204 +0 . 8 6 0 8 * - 0 . 3519 + 0 .4721 - 0 .0707 + 0 . 0493 Y i - - 0 . 0467 +0 .2823 - 0 .2927 +0 .2497 - 0 . 3542 - 0 . 0902 - 0 .1 265 - 0 . 1760 Y l 5 + 0 . 2649 +0 .1342 + 0 .2716 +0 .4950 - 0 . 0638 + 0 .391 1 - 0 . 0 383 + 0 .0847 Y l 6 - 0 . 5791. + 0 .31 52 - 0 . 7 8 3 1 * -0 .1386 - 0 .5668. - 0 .6643 - 0 . 4277 . - 0 . 6520 . Xi x 2 x 3 «v ™ 6 x 8 . x 7 Xi + 1 .0000 x 2 -0 . 4694 + 1 .0000 x 3 +0 .8227 - 0 .4858 + 1 .0000 X. . +0 . 8353 -0 .4681 + 0 . 9773 + 1 .0000 X 5 +0 .6181 - 0 .8322 +0 .5857 +0 .6523 + 1 . 0000 X 6 +0 .7337 - 0 .6860 + 0 . 8425 + 0 .8982 +0 . 8968 + 1 . 0000 Yi +0 .5306 - 0 . 7 3 3 6 * +0 .5857 +0 .5225 + 0 . 6030 +0 . 5820 Y 2 +0 . 7 3 8 0 * -0 .5472 + 0 . 6448 + 0 . 6235 + 0 . 5 135 + 0 . 541 3 Y 3 +0 . 5 7 6 9 * - 0 .4978 + 0 . 3565 + 0 . 3362 + 0 . 5483 +0 . 4025 Y- +0 . 4695 - 0 . 6 5 2 3 * + 0 .2840 +0 . 2272 + 0 . 5688 +0 . 3553 Y 5 + 0 . 7 6 7 3 * - 0 .3868 + 0 . 6748 + 0 . 63 71 + 0 . 3 7 1 5 . +0 . 4895 Y 6 +0 . 5 9 4 4 * - 0 .4059 +0 .4426 + 0 . 3662 + 0 .2827 + 0 . 2940 Y 7 +0 .6849 - 0 .5525 + 0 . 6254 +0 . 7195 + 0 .6951 + 0 . 7 3 0 7 * Y.8 +0 . 7 4 1 4 * - 0 . 4468 +0 .5723 + 0 . 6724 + 0 . 6424 +0 . 6747 Y 9 + 0 .3329 - 0 .0945 +0 .5401 + 0 .607 2 * + 0 . 2 1 6 3 . + 0 .4570 Yio + 0 .41 05 - 0 .0329 +0 .5931 +0 . 6 5 5 8 * + 0 . 1868 +0 . 4610 Y n +0 .0699 +0 .1951 +0 .1483 + 0 . 1 646. - 0 . 0433 + 0 . 0796 Y l 2 +0 .1988 +0 . 1 282 + 0 .1330 +0 . 1440 - 0 . 0089 + 0 . 0779 Y l 3 +0 .3294 +0 .0709 + 0 .5178 +0 . 5 2 5 8 * + 0 . 1 2 6 4 . + 0 .3797 Ym + 0 . 6 2 7 0 * - 0 .4357 +0 .5724 + 0 .5201 +0 . 3786 + 0 .4671 Yis -0 .0671 - 0 .3094 + 0 . 1893 +0 .1806 +0 . 3025 + 0 . 3086 Y l 6 +0 . 2448 - 0 . 7 2 1 4 * +0 .2316 + 0 . 1487 ' + 0 . 4620 + 0 .2808 X i x 2 X.3 X- X 5 x 6 x 8 x 7 . X i , + 1 . 0000 x 2 - 0 . 6307 + 1 .0000 . x 3 + 0. 6333 -0 . 5447 + 1 .0000 x 4 + 0. 6357 -0 .4978 +0 .9949 + 1 .0000 X 5 +0. 32 32 -0 .7609 -0 .0917 -0 .1 265 + 1 .0000 x 6 +0 . 0088 -0 . 5546 -0 .0511 -0 .1419 +0.5525 + 1 .0000 + 0. 7378 -0 .7757 +.0 .6525 + 0 .6707 +0.5438 -0 .0789 + 1 .0000 x 8 +0. 5740 -0 .9802 + 0 .41 07 + 0 .3626 +0.8580 + 0 .5985 + 0 .7452 + 1 .0000 Y i +0. 1180 . +0 .2347 -0 .4677 -0 .4276 +0.1076 -0 .2934 -0 .0731 . -0 .1969 Y 2 +0. 2402 +0 .01 60 -0 .41 22 -0 .4086 +0.2954 +0 .0691 -0 .0609 + 0 .0465 Y 3 +0. 7195* -0 .2590 +0 .1983 + 0 .2139 +0.1712 -0 .1118- +0 . 3570 + 0 .2155 Y* +0. 5870* -0 .2245 + 0 .0023 + 0 .0071 +0.2622 + 0 .0201 • +0 .2293 +0 .21 56 Ys +0. 5384 -0 .0761 + 0 .1641 +0 .1443 -0 .1448 + 0 . 1 277 -0 .0853 -0 .0125 Y 6 + 0. 5325 • -0 .1095 +0 .1864 +0 . 1 654 -0 .1286 +0 .1407 -0 .0618 + 0 .01 38 Y 7 +0. 4465 -0 .0094 +0 .0384 + 0 .01 69 . -0.11 06 + 0 .1603 -0 .1610 -0 .041 3 Y 8 ' +0. 4345 +0 .0438 +0 .0272 +0 .01 57 -0 .1628 + 0 .0611 -0 .1622 -0 .1065 Y 9 - 0 . 0718 + 0 .2132 -0 .0462 -0 .0789 -0 .3624 +0 .20 57 - -0 .4748 -0 .2773 Yio - 0 . 1 264 +0 .2150 -0 .0520 -0 .0941 -0 .3886 +0 .2826 -0 .5447 -0 .2874 Y i i +0. 1 458 -0 .2957 +0 .3090 + 0 .2592 -0 .0161 +0 .4128• -0 .0210 + 0 .2137 Y l 2 +0. 1619 -0 .4070 + 0 .3238 + 0 .2825 +0.2070 + 0 .3892 + 0 .2053 +0 .3961 Y l 3 +0. 2349 -0 .5744 +0 .4771 * + 0 .4071 +0.1714 +0 .6233* +0 . 1 538 + 0 .4852 +0. 1809 -0 .2531 +0 .2183 +0 .1727 -0 .0186 +0 .3813 -0 .0704 + 0 .1612 Y i s - 0 . 051 6 -0 .3972 -0 . 1 545 -0 .21 51 +0.4521 + 0 .6543* -0 .0548 -0 .0407 Y l 6 - 0 . 3536 + 0 . 6578 -0 .2916 -0 .2524 -0 .5816 -0 .4632 -0 .4831 . -0. .6947* r o t - X i X 2 X 3 x 6 x 8 x 7 X i + 1 . 0 0 0 0 x 2 - 0 . 6 3 0 7 -1 . 0 0 0 0 x 3 +0 . 6 3 3 3 - 0 . 5 4 4 7 + 1 . 0 0 0 0 x 4 - 0 . 1 6 7 4 +0 . 3 9 4 6 - 0 . 5 6 2 5 + 1 . 0 0 0 0 x 5 + 0 . 7 3 7 8 - 0 . 7 7 5 7 +0 . 6 5 2 5 +0 . 0 4 1 5 + T . 0 0 0 0 x 6 + 0 . 5 9 2 0 - 0 . 9 7 8 4 +0 . 4 6 3 1 - 0 . 5 0 3 9 + 0 . 8 1 1 9 + 1 . 0 0 0 0 Yi -.0 . 2 6 2 7 +0 . 1 1 6 9 * - 0 . 3 3 3 0 - 0 . 5 0 3 9 - 0 . 6 6 3 5 * - 0 . 2 2 5 0 Y 2 - 0 . 1 3 9 4 * + 0 . 1 6 1 0 * - 0 . 4 0 9 2 - 0 . 3 7 2 8 - 0 . 6 5 5 3 * - 0 . 2 6 6 5 Y 3 +0 . 5 5 7 3 - 0 . 2 2 0 1 +0 . 2 3 5 2 - 0 , . 11 98 + 0 . 1 8 3 3 +0 . 1 2 6 4 Yt, +0 . 0 2 7 5 - 0 . 2 4 5 2 +0 . 2 7 4 3 - 0 . 4 9 7 8 - 0 . 0 1 98 + 0 . 1 0 4 9 Y 5 +0 . 6 3 0 0 * +0 . 0 2 9 3 +0 . 1 9 5 4 - 0 . 1 3 4 8 +0 . 0 2 2 3 * - 0 . 0 9 0 9 Y 6 +0 . 4 2 8 2 +0 . 1 0 5 5 +0 . 0 9 3 6 - 0 . 2 6 3 3 - 0 . 1 9 6 2 - 0 . 2 2 1 8 Y 7 +0 . 3 9 3 1 - 0 . 0 3 8 1 +0 . 5 8 8 3 - 0 . 5 7 2 2 •+0 . 0 0 4 8 - 0 . 1 2 7 8 Y 8 +0 . 5 6 2 6 - 0 . 1 4 9 7 + 0 . 4 3 5 7 * - 0 . 4 3 8 9 + 0 . 0 6 1 1 * - 0 . 0 0 7 8 Y 9 - 0 . 0 1 3 1 - 0 . 1 0 1 6 +0 . 1 591 - 0 . 7 5 1 2 - 0 . 3 5 2 8 - 0 . 0 2 8 4 Yio +0 . 1 5 4 5 - 0 . 2 1 1 0 +0 . 1 2 0 3 - 0 . 6 6 9 9 * - 0 . 2 5 6 5 + 0 . 0 6 6 2 Y n . - 0 . 4 1 0 9 +0 . 2 3 7 0 - 0 . 0 6 8 9 - 0 . 3 8 8 9 - 0 . 4 9 7 5 * - 0 . 3 1 7 5 Y12 - 0 . 5 6 6 8 +0 . 4 0 1 8 - 0 . 2 1 3 2 - 0 . 4 0 9 5 - 0 . 7 2 8 6 * - 0 . 4 8 9 7 Y 1 3 - 0 . 5 7 9 7 * - 0 . 2 0 4 3 - 0 . 1 4 7 6 - 0 . 3 6 7 7 - 0 . 4 9 1 4 - 0 . 2 4 7 4 Ym - 0 . 4 2 5 4 +0 . 1 8 3 8 - 0 . 1 6 3 1 - 0 . 4 4 3 9 - 0 . 5 6 4 3 - 0 . 3 0 5 7 Yis - 0 . 4 7 7 3 +0 . 1 7 4 7 - 0 . 0 8 3 5 - 0 . 3 9 2 3 - 0 . 4 4 0 3 - 0 .1 5 2 8 Y l 6 - - 0 . 3 4 2 3 - 0 . 7 6 9 5 * - 0 . 5 3 2 6 - 0 . 4 8 3 0 - 0 . 5 3 9 4 - 0 .71 58 APPENDIX 4 A t t e n u a t i o n Va lue s f o r the Four S p e c i e s A t t e n u a t i o n Va lue s i n D e c i b e l s * Sound l e v e l meter a t s e t t i n g ' A ' + Sound l e v e l meter a t s e t t i n g ' C S.D. S t anda rd d e v i a t i o n WIN. W i n t e r SUM. Summer FREQ. F requency i n c y c l e s per second STAND 1 STAND 2 STAND 3 ' ' STAND 4 Av. S.D. Av. S.D. FREQ. WIN. SUM. WIN. SUM. WIN. SUM. WI N. SUM. WINTER SUMMER * 125 - 0 . 7 1 .5 -3 .9 2.5 -0.9 0.8 1 .6 -1 .3 -1 .0- ; 2,3 ' 0.9 1 . 6 125 + - 4 . 8 2.3 . - 7 . 8 2.5 -4.6 1 .5 -0 .6 4.3 - 4 . 4 3.0: 2.6 1 .2 * 250 6.7 11.3 '7.4 12.0 5.7 8.8 8.9 15.5 7.2 1 .4 11.9 2.8 250 + 7.0 11.6 7.8 12.1 6.3 8.6 9.3 16.1 7.6 1.3 12.1 3.1 500* 3.2 0.3 6.2 5.8 3.2 0.8 3 . - 5.0 4.0 1 .5 2.9 2.8 500 + 3.1 -0 .9 6.9 4.9 3.4 0.1 ' 3.9 4.1 4.3 1.7 2.1 2.9 1000* - 7 . 6 - 4 . 8 7.4 8.3 -2.1. - 3 .8 -2 .9 . 0.8 -1 .3 6.3 0.1. 5.9 1 0 0 0 f -7.1 -3 .6 8.9 7.9 -1.9 -2.1 - 2 .9 1 .1 - 0 . 8 6.8 0.8 5.1 2000* 5.9 4.9 0.2 . 1 .4 11.4 -0 .6 2.4 1 2 . 6. 5.0 4.9 4.6 5.8 2000 + 5.6 3.6 -0 .6 1 .1 10.9 -0 .6 2.4 11.4 4.6 4.9 3.9 5.3 4000* 2.7 9.5 12.7 - 4 .3 0.4 - 7 . 8 - 2 . 3 5.8 3.4 6.5 0.8 8.1 4.0 00 + • 2.4 6.9 14.9 .-4.4 0.9 -7.9 -1 .1 5.4 4.3 6,9 0.0 .7.2 8000* 6.7 -1 .5 10.7 - 6 . 5 -1 .1 - 0 . 5 4.9 15.3 5.3. .4 .9 1 .7 9.4 8000 + 4.8 1.5 11.3 - 5 .3 3.8 0.8 1.6 17.5 5.4 4.2 3.6 . 9.7 12000* 10.1 5.0- 7.1 - 2 .0 1 .9 - 0 . 3 8.1 5.3 6.9 3.5 2.0 3.7 12000 + 10.9 9.0 7.2 13.0 6.4. 11.5 7.7 5,8 8.1 2.0 9.8 3.2 FREQ. STAND 1 STAND 2 STAND 3 STAND 4 ,Av. S.D. Av. S.D. WIN. SUM. WIN. SUM. WIN . SUM.. • WIN. SUM. WINTER , SUMMER * 1 25 2.2 3.6 -1 .8 7.9 0.9 8.6 1 .2 10.9 0.6 1 .7 7.8 3.0 1 2 5 f - 0 . 4 4.0 -1 .7 7.0 1 .3 7.0 - 0 . 2 9 .5 - 0 . 3 1 .2 6.9 2.3 * 250 10.9 17.6 11 .4 16.4 9,9 18.9 15.4 21 .9 11.9 2.4 18.7 •2.4 250 + 10.8 17.3 11.6 16.0 9.8 19.8 15.3 21 .3 11.9 2.4 18.6 . 2 . 4 * 500 2.3 1 .9 12.8 10.1 9.0 2.6 8.0 12.1 8.0 3.3 6.7 5.2 500 + 2.4 2.0 12.4 10.5 5.4 2,5 8.6 14.8 7.2 4.3 7.4 6.2 1000* 1 7 12.1 2.2 1 .4 5.2 7 - 4 0.2 3.6 2.3 2.1 6.1. 4.7 1 000 + 2.9 11.3 0.9 2.3 5.9 8.3 -1 .1 4.5 2.1 3.0 6.6 4.0 2000* 2.1 6.0 2.8 1 .0 8.6 6,8 - 2 .2 8.3 2.8 4.4, 5.5 3.1 2000 + 2.6 5.0 4.6 1 .8 10.3 8.0 - 0 . 4 7.8 4.3 4,5 5.6 2.9 4000* 5.4 3.1 10.4 1 .9 8.9 13.1 7.6 10.4 8.1 2.1 7.1 5.5 4000 + • 6.9 5.9 11 .6 3.9 9.6 13.6 7.1 11.6 8.8 2.3 8.8 4.6 8000 * 16,5 8.0 , 15.0 - 0 . 3 13.7 6.8 14.3 23.8 14.9 1 .2 9.6 10.1 8000 + i 16.1 8.1 12.3 -0.1 15.8 14.4 10.8 16.1 13.8 2.6 9.6 7.4 12000* 5.3 7.T 5.3 8.4 5.3 9.4 5.3 10.4 5.3 0.0 8 . 8 1 .4 12000 + 12.6 - 6 . 5 10.9 13.5 11.1 8.5 12.1 12.5 ' 11 .7 0.8 7.0 9.3 STAND 1 STAND•2 STAND 3 STAND 4 Av. S.D. Av. S.D. FREQ. WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WINTER • SUMMER * 1 25 0.8 4.9 2.1 6.6 4.1 4.1 3.6 1 1 .6 2.6 1 .5 6.8 3.4 125 + 1.8 7.6 - 0 . 4 6.9 2.1 7.4 2.1 14.1 1 .4 1 .2 9,0 3.4 * 250 13.4 16.3 10.9 18.3 15.7 16.8 10.4 24.5 14.1 2.5 18.9 3.8 250 + 13.9 18.1 10.9 17.6 16.4 16.6 16.7 25.4 14.5 2.7 19.4 4.0 500* 6.3 4.4 11.8 13.6 9.3 6.4 8.8 6.1 9.1 2.3 7.6 4.1 500 + 7.5 5.3 11.8 13.8 10.0 6.5. 11 .8 6.8 10.3 2.0 8.1 3.8 1000* - 2 . 3 4.1 . 2.8 15.4 -1 .3 1 .4 3.3 5.6 0.6 2.8 6.6 6.1 1000 + 1 .3 5.5 6.3 16.0 4.0 1 .0 11.3 5.8 5.7 4.2 7.1 6.3 2000* 5.9 2.9 3.6 5.1 -0.1 1.9 - 2 . 4 4.4 1 .8 3.7 3.6 1.5 2 0 0 0 f 7.0 0.1 5.3 6.4 1 .0 0.6 - 0 . 5 5.9 3.2 3.5 3.3 3.3 4000 * 10.9 12.9 15.6 11.6 5.6 15.6 1.9 18.4 8.5 6.0 14.6 3.0 4000 + 9.6 9.9 15.4 9.6 6.4 14.6 5.4 16.6 9.2 4.5 12.7 3.5 8000* 12.3 10.9 10.8 8.9 12.3 20.4 6.3 23.1 10.4 2.8 15.8 7.0 8000 + 16.8 11.8 14.1 18.8 14.1 14.8 12.1 22.0 .413 2.0 16.8 4.5 12000* 0.9 3.3 0.9 7.8 0.9 8.3 0.9 ' 9,3 0.9 0.0 7.0 2.6 12000 + 13.9 6.0 9.1 13.0 13.1 8.0 12.1 18.3 12.1 2.1 11.3 5.5 FREQ. STAND 1 STAND 2 STAND 3 STAND 4 STAND 5 Av. S.D. Av. S.D. WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WINTER SUMMER * 125 8.3 3.8 4.6 1 .8 7.8 13.5 6.1 8.0 6.1 7.3 6.6 1 .5 6.9 4.5 1 2 5 + 4,9 4,0 2.9 3.8 4.2 15.8 4.9 6.3 2.9 8.8 4.0 1 .0 7.7 4.9 . * 250 13.9 11.5 12.4 10.5 10.2 15.3 12.9 9.8 17.4 9.8 13.4 2.6 1 T.4 2.3 250 + 13.5 11 .6 12.8 10.1 12.8 15.1 14.0 10.4 19.3 10.4 14.5 2.7 11.5 2 .1 * 500 . 4.9 - 2 . 5 12.7 -1 .5 8.7 1 .3 -0 .6 -1 .5 - 1 . 6 - 5 . 3 4.8 6.1 - 2 .4 2.5 500 + 5.9 - 2 .9 15.1 -1 -9 8.1 0.4 -0 .9 - 4 . 9 -1 .6 -6.1 5.3 6.9 -3.1 2.6 1000* -3.1 2.5 - 4 . 4 - 3 . 3 4.6 3.3 - 3 . 4 0.8 - 2 .9 4.5 - 1 . 8 3.7'' 1.6 3.0 1 000 + -3.1 3.6 - 4 . 4 -2 .9 4.6 3.1 - 2 . 4 1.1 -3.1 3.9 -1 .7 3.6 1.8 2.8 2000* 2.7 - 5 .6 -1 .6 -5 .9 14.7 16.6 6.7 3.9 13.2 -1 .6 7.1 6.9 1.5 9.4 2000 + 2.1 - 5 . 6 -1 .9 -6.1 13.9 14.9 7.9 4 - 1 8.9 -1 .1 6.2 6.1 1.2 8.7 4000 * 3.2 - 3 . 8 4.2 - 3 . 5 16.7 15.8 11.2 5.0 3.7 0.5 7.8 6.0 2.8 8.1 4 0 0 0 + 3.9 -5.1 4.9 -4 .9 16.9 15.7 10.1 4.9 5.6 -0 . 4 8.3 5.4 1.9 8.4 8000* 8.9 12.0 -1 .3 2.5. 6.4 19.5 4.9 8.8 2.9 9.8 4.4 3.9 1.0.5 .6.1 8000 + 4.1 10.0 - 2 - 7 2.8 6.1 21 .5 3.8 13.5 0.-6 10.5 2.4 3.4 11.7 6.8 12000* 4.4 - 3 . 0 2.1 - 3 . 3 10.6 17.8 8.9 7.8 2.1 3.5 5.6 3.9 4.6 8.7 12000 + - 2 . 6 - 0 . 3 -1 .3 - 4 . 0 1.9 6.5 1 .4 9.8 - 2 , 3 - 0 . 5 - 0 . 6 2.1 2.3 5.6 FREQ. STAND 1 STAND 2 STAND 3 STAND 4 STAND 5 Av. S.D. Av. S.D. WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WINTER SUMMER * 125 8.2 9.4 7.7 6.9 2.4 13.6 8.2 6.9 8.2 16.6 6.9 2.5 11.9 3.8 1 2 5 + 6.6 9.3 8.1 6.0 6.1 14.3 9.8 10.8 10.8 11.3 8.3 2.0 10.3 3.0 * 250 20.4 20.6 21 .6 16.9 18.1 22.4 23.4 26.4 22.1 16.9 21 .1 2.0 20.6 4.0 250 + 17.1 19.8 16.6 15.3 17.8 22.8 24.6 32.8 22.6 14.3 19.7 3.6 21 .0 7.4 500* 10.8 - 0 . 4 1 2.8 8.6 10.0 2.4 5.8 5.1 5.8 '2.6 9.0 3.1 3.7 '3.4 5 0 0 f ' 8.1 - 0 . 5 10.1 6.5 10.4 2.5 6.1 5.0 ' 6.6 0.0 8.3 1 .9 2.7 3.1 1000* 0.2 15.4 0.4 2.6 6.9 4.9 13.9 12.9 4.9 4.1 5.3 5.6 . 8.0 5.7 1000 + -1.1 14.3 -0 .9 4.3 6.1 5.8 12.4 . 1 1 . 8 4.9 4.0 4.3 5.6 8.0 4.7 2000* 13.8 4.0 0.3 0.3 9.3 8.0 10.8 2.0 9.8 12.5 8.8 5.1 5.4 4.9 2000 1" 15.6 3.3 0.8 0.3 9.1 9.8 12.1 2.5 9.1 14.0 9.3 5.5 6.0 5.7 4000* 16.9 3.4 6.6 3.6 16.6 13.1 10.6 8.6 19 .4 15.6 14.0 5.2 9.1 5.9 4000 1" 16.4 5.1 . 8.4 3.9 17.4 20.9 14.9 10.9 21 .6 10.1 15.7 4.8 10.2 6.7 . 8000 * 9.5 3.3 10.8 -1 .8 . 1 1 . 8 13.0 17.0 12.8 13.3 6.8 12.5 2.9 6.8 6.3 8000 + 4.6 3-4 5.3 1.1 8.1 14.6 13.1 10.6 11 .1 0.1 8.4 3.6 6.0 6.3 12000* 5.3 11 .6 0.8 2.1 5.3 9.9 4.3 13.9 5.3 11.9 4.2 1 ,9 9.9 4. 6 12000 + -2.1 7.5 . -2.1 9.0 2.1 11.8 5.6 1 3 .3 3.4 - 0 . 8 1 .4 3.4 . . 8.2 . .5.5 STAND 1 STAND 2 STAND 3 STAND 4 STAND 5 Av. S.D. Av. S.D . FREQ. WIN. SUM. • WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WINTER SUMMER * 1 25 8,8 16.4 7.3 10.4 8.8 14.6 8.8 12.9 8.8 21 .9 8.5 0.7 1.5.2 4.3 1 2 5 + 6.8 . 15.6 7.1 9.6 9.1 17.1 .63. 21 .9 11.6 17.9 10.2 3.9 16.4 4.5 * 250 17.7 22.3 19.2 20.3 14.4 18.5 21 .2 24.0 21 . 2 17.3 18.7 2.8 19.3 2.7 250 + 13.9 19.4 13.7 19.6 13.4 20.1 21 .2 11.9 18.9 22.9 16.2 3.6 18.8 4.1 * 500 13.8 7.4 11 .1 7.4 11.3 3.1 3.1 14.1 5.6 3.4 9.0 • 4.5 7.1 4.5 500 + 7.0 7.8 9 .3 7.3 9.0 3.3 3.8 6.3 6.3 3.8 7.1 2.2 5.7 2.0 1000* - 0 . 5 6.1 1 .3 6.9 -3 .8 10.1 - 0 .8 7.6 8.0 14.9 0.9 4.4 9.1 3.6 1 000 + 6.8 6.8 • 5.0 5.0 2.0 10.0 2.5 2.9 11 .8 20.0 5.6 3.9 9.8 6.0 2000* 13.1 6.6 2.9 5.4 5.1 2.1 5.1 2.4 . 4.6 2.6, 6.2 4.0 3.8 2.0 2000 + 12.0 7.6 3.0 5.4 6.3 3.6 6.3 1 .0 4.5 2.9 6.4 3.4 4.3 2.3 4000 * 11.1 TO. 9 6.6 - 2 .4 11 .4 7.9 13.4 .7.1 9.1 5.1 10.4 2.6 5.7 5.0 4000^ 9.6 8.1 6.4 - 4 . 4 9.4 6.6 11 .4 3.1 •11.4 4.9 9.7 2.0 3.7 4.9 8000 * 9.8 6.6 1 .3 -3 .4 - 2.8 5.6 2.6 2.1 12.8 .7.1 5.9 5.1 3.6 4.4 8000 + 5.1 7.5 4.6 8.3 6.3 15.3 9.6 : 15.0 10.8 5.0 7.3 2.8 10.2 4.7 1 2000* -1,. 1 0.8 01 .6 5.5 0.9 9.8 . 0.9 - 3 . 0 0.9 0.5 0.0 1 .2 2.7 5.0 1 2000 + - 3 .1 2.5 - 0 . 4 7.8 0.9 6.0 6.1 6.8 3.4 - 3 . 0 1 . 4 3.5 . 4.0 4.4 FREQ. STAND T STAND 2 STAND 3 STAND 4 STAND 5 Av. S.D. Av. S.D. WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. 0 WIN. SUM. WINTER • SUMMER * 1 25 -1 .7 4.0 5.8 1 .0 5.1 3.0. 9.1 7.5 3.8 7.5 4.4 3.9 4.6 2.9 1 2 5 + - 2 . 3 ' 4 . 3 6.7 3.0 2.7 4.5 5.7 8.5 2.9 9.8 3.1 3 .5 6.0 2.9 * 250 7.9 11 .0 12.7 12.3 16.4 16.5 13.7 13.5 13.4 14.5 12.8 3.1 13.6 2.1 250 + 8.3 11.1 13.8 13.4 19.0 17.1 13.5 13.9 14.3 15.6 13.8 3.8 14.2 2.3 * 500 3.7 7.3 5.2 1 .0 7.7 4.8 10.2 3.5 5.2 - 3 . 0 6.4 2.6 2.7 3.9 5 0 0 f 2.9 6.4 5.6 0.6 8.9 5.1 9.6 3.1 . '6 .1 - 3 . 4 6 .6 2.7 2.4 3.9 1000* 2.T 14.8 -2.1 -1 .8 0.4 0.5 5.9 14.0 6.1 - 2 . 0 2.5 .3.6 5.1 8.5 1 0 0 0 + 3.9 14..9 - 2 . 6 0.9 0.1 5.4 15.9 6.4 -1 .1 2.8 .3 .7 5.7 8.8 2000* 1.9 7.1 8.9 -3.1 2.7 5.4 12.4 3.9 6.4 6.9 6.5 4.4 4.0 4.2 2 0 0 0 + 1 .1 5.6 7.4 - 3 .6 2.1 5.1 11 .9 5.9 4.4 6.6 5.4 4.4 3.9 4.3 4000 * 8.2 14.3 5.7 0.5 11 .2 7.0 17.9 5.0 7.4 0.0 10.1 4.8 5.4- 4.8 4000 + 8.4 12.1 6.1. - 0 .9 9.1 6.0 16.9 3.6 5.6 -1 .4 9.2 4.5 3.9 5.6 8000* 5.7 13.3 3.7 1.0 5.9 9.3 16.2 7.8 5.2 8.0 7.5 5.0 7.9 4.4 800 0 + • 4.3. 15.5 3.1 2.8 3.3 9.5 11 .8 9.0 1.3 7.5 4.8 4.1 8.9 4.6 12000* 3.9 7.5 7.6 2.8 11 .1 3.3 11 .1 3.8 10.1 2.3 8.8 3.1 3.9 2.1 1 2000 + 3.7 14.0 3 4 11 .0 11.2 15.3 6.7 3.8 . . 8.2 5.8 6 . 6 .V? in.n 5 n STAND 1 STAND 2 STAND 3 STAND 4 STAND 5 Av. S.D. Av. S.D. FREQ. WIN.. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WINTER SUMMER. * 125 -1 J 5.1 6.9 3.6 7.2 4.9 10.2 11 .9 7.7 15.9 5.9 4.2 8.3 5.3 1 2 5 + - 1 . 2 5.5 6.2 3.8 7.3 2.8 16.3 13.5 8.1 21 .8 6.7. 6.3 9.5 8.1 * 250 11.6 20.1 15.6 24.4 16.9 20.1 20.4 19.1 21 .6 25.9 16.8 3.5 21 .9 3.0 250 + 11.6 18.3 16.1 25.3 20.1 21.9 16.6 19.0 21.3 31 .3 18.0 4.1 23 .0 5.4 * 500 7.8 4.9 7.0 1 .9 9.5 1 .1 10.5 1.1 12.8 0.6 8.0 2.1 1.9 1 .7 500 + 7.1 5.5 6.4 2.0 12.4 1 .8 1 .0 10.1 : 1 .0 7.7 2.7 2.3 1 .9 1 000 * 0.9 5.1 2.2 -2.1 -3 .6 -3.1 13.4 10.1 0.4 6.6- 4.0 6.5 3.3 5.7 1 000 + 1.1 5.5 1 .9 - 0 . 8 -3 .6 -1 .8 10.1 14.3 - 0 . 9 5.5 3.1 5.2 4.4 5.4 2000* 7.3 16.8 4.3 4.8 - 4 .4 2.3 8.3 6.8 . 0 . 3 5.5 3.7 5.0 7.2 5.6 2000 + 7.3 16.5 4.6 5.0 - 4 .4 4.0 8.6 8.0 . 0.8 8.0 3.8 5.1 8.3 4.9 4000* 16.4 13.1 15.6 2.6 10.4 9.6 9.9 15.6 6.6 8.6 14.1 3.7 9.9 4.9 4 0 0 0 + 15.9 14.6 15.4 4.1 10.9 11 .6 8.1 18.1 8.4 10.9 14.8 4.3 11 .9 5.2 8000 * 17.3 22.8 5.8 1 .3; 7.0 12.0 11.3 14.8 10.8 9.0 10.7 4.6 12.0 7.9 8000 + 5.1 13.1 9.3 2.1 8.6 6.9 10.6 2.1 5.3 8.4 8.8 2.2 6.5 4.6 12000* 5.3 17.4 3.0 6.9 5.3 5.6 5.3 15.9 0.8 10.1 4.8 1.0 11 .2 5.3 12000 + - 3 . 6 13.0 1 .9 5.6 8.9 8.8 9.1 -1 .5 -2.1 13.8 4.9 5.7 7.9 6.2 FREQ. STAND 1 STAND 2 STAND 3 STAND 4 STAND 5 Av. S.D. Av. S.D. . WIN-. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WINTER SUMMER * 125 1 .8 6.6 6.8 2.6 7.3 8.1 8.8 16.1 7.3 14.4 6.7 2.9 9.6 5.6 1 2 5 + 1 .6 7.9 11 .1 4.6 5.6 9.9 16.5 9.4 7.1 16.9 9.1 5.7 •9.7 4.5 * 250 15.7 18.5 18.7 22.3 18.2 21 .3 21 .7 27.0 19.2 24.0 19.2 2.6 22.6 3.2 250 + 12.9 16.1 16.9 .17.9 21 .2 20.6 21 .4 17.4 13.7 27.9 19.0 4.0 20.0 4.7 * 500 4. 3 9.4 11.3 9.9 3.8 1 .1 16.3 4.4 11 .1 -2 .9 9.1 5.2 4.4 5 .4 t 500 4.3 10.8 12.5 8.5 6.3 1 .8 15.8 4.5 9.3 - 2 . 0 9.7 4.6 4.7 5.1 1000* - 5 . 5 . 7.6 . 6.3 3.1 - 7 . 5 6.6 "12.3 14.9 1 .3 '5.1 3.6 9.3 7.5 4.5 1 0 0 0 + - 0 . 8 8.0 : 8.5 2.8 - 3 . 8 9.0 14.8. 11.5 5.0 5.8 6.3 8.2 7.4 3.3 2000* 0.1 6.9 .3.4 0.4 -9 .6 4.6 7.6 9.4 2.9 1 .4 0.2 6.4 5.1 3.7 2000 + 2.3 7.1 5.5 1 .6 - 7 . 8 5.1 8.8 10.4 3.0 1 .4 1 .8 6.2 5.1 3.8 4000 * 14.9 20.9 16.1 10.9 9.9 8.1 12.6 16.1 6.6 11.6 12.3 3.3 13.5 5.0 4000 + 1 4.1 14.6 15.6 10.9 12.9 6.1 15.1 12.1 6.4 11.4 1 3.6 2.2 11.0 3.1 8000 * 8.3 20.6 6.8 2.9 6.8 8.6 11.8 14.1 1 .3 8.6 7,2 3.5 11 .0 6.7 8 0 0 0 + 4.6 17.8 9.8 17.8 12.8 19.0 14.1 11 .3 4.6 21 .3 10.2 3.7 17.4 3.7 12000* -0.1 5.8 -10.1 3.8 0.9 11.3 0.9 10.8 -1 .6 2,3 -1 .5 4.8 6.8 4.1 12000 + -1 .1 9.0 13.1 13.8 12.6 11 .0 8.9 9.0 -0 .4 12.5 8.3 5.7 9.9 4.1 STAND T STAND 2 STAND 3 STAND 4 Av. S.D. Av. S.D., • FREQ. WIN. SUM. WIN. SUM. WIN. SUM. WIN. SUM. WINTER SUMMER * 125 5.6 4.5 7.3 3.0 6.1 2.5 1 .6 5.3 5.1 2.5 3.8 1.3 1 25 1" 3.9 5.8 2.9 4.3 3.-2 4.0 - 2 . 3 5.0 1.9 2.9 4.8 0.8 * 2 50 9.2 10.5 '15.4 13.8 10.4 10.3 8.7 12.0 10.9 3.1 11.6 1.6 • 250 + 9.8 10.9 15.8 14.1 11 .3 10.6 12.5 12.6 12.3 2.6 12.1 1.6 * 500 2.9 - 2 . 3 0.9 1.0 0.4 - 2 .8 0.4 - 6 . 0 1.2 1.2 - 2 . 5 2.9 500 + 2.6 - 4 .4 0.4 1 .6 0.9 -3.1 0.9 - 6 . 4 1.2 1.0 - 3 . 1 . 3.4 1 000* -4.1 - 3 .8 - 2 .9 -2 .8 -6.1 -3 .8 . - 3 .6 -6 .8 ) - 4 .2 1.4 - 4 . 3 1.7 1 000 + - 4 . 4 -2 .6 - 2 .9 -2.1 -4 .9 - 2 .9 -3 .6 - 5 . 4 - 3 . 9 0.9 -3 .2 1.5 2000* 0.7 - 6 .9 6.4 2.4 . 0-2 - 0 .6 -5.1 . -7.1 0.6 4.7 -3.1 4.7 2000 + : - 1 . 4 - 7 . 4 6.4 3.4 -0 .6 -2 .9 -5 .4 -7 .9 - 0 . 3 4.9 - 3 .7 5.2 4.000* •1.7 0.8 10.7 4.8 4.2 3.8 - 0 .8 0.3 3.9 4.9 2.4 2.1 4000 + 6.1 2.9 12.6 1.9 6.1 4.4 -0 .9 2.4 6.0 5.5 2.9 1.1 8000* 2.4 0.8 11 .9 14.5 3.2 10.8 -0.1 6.3 4.4 5.2 8.1 5.9 8000 + 1 .3 3.3 8.6 18.8 2.3 11.5 1 .8 5.8 3.5 3.4 9.8- 6.9 12000* 6.6 - 2 . 0 10.6 4.0 8.1 6.8 . - 1 . 9 - 1 . 5 5.9 5.4 1.8 4.3 1 2000 + 1 .9 5.0 -0 .6 5.8 -0 .3 2.5 -0 .6 2.3 0.1 1.2 3.9 1.8 STAND 1 STAND 2 STAND 3 STAND 4 Av. S.D. Av. S.D. FREQ. WIN. SUM . WIN. SUM. WIN. SUM. • WIN. SUM. WINTER SUMMER ' * 125 5.7. 6.9 6.7 3.1 7.2 7.1 0.4 5.9 5.0 3.1 5.8 1.8 125 + 3.6 7.2 5.6 2.2 5.6 7.5 - 0 .4 6.5 3.6 2.8 5.9 2.5 250* 14.4 15. 6 °1 5 .6 14.4 14.4 17.6 18.6 20.1 15.8 2.0. 16.9 2.5 250 + 14.3 16.3 14.8 13.3 14.3 17.6 14.1 18.5 14.4 0.3 16.4 2.3 * 500 4.5 5.0 2.9 2.5 -0.1 1.0 0.9 3.3 1.8 0.6 1.7 500 + 3.9 -0 .8 5.6 2.3 3.4 - 0 . 5 1 .9 0.5 3.7 1.6 0.4 t . 4 1 000* -4 .T -1 .9 2.9 -0 .6 -4.1 -0 .9 -2 .6 -4.1 - 1 . 9 3.3 - 1 .9 1.6 1000 + - 5 . 4 -1 .5 4.1 0.3 -3 .6 -1 .8 -2 .6 - 2 . 5 - 1 .9 4.2 - 1 . 4 . 1.2 2000* ' - 4 . 9 6.0 3.6 -0 .3 -0 .9 -5 .8 - 6 .2 10.0 -2.1 4.4 - 2 . 5 6.9 2 0 0 0 + - 4 .9 4.5 4.1 -0 .5 1 .6 - 5 . 3 -6 .9 - 9 . 5 . -1.6 5.2 - 2 .7 6.0 4000 * 14.9 - 4 . 4 15.9 4.4 9.9 2.6 -0.1 - 3 .9 10.1 7.3 - 0 . 3 4.5 4000 + 11 .6 -3 .6 11 .9 7.1 8.1 5.1 •1 .1 - 2 .6 8.2 5.0 1.5 -5.4 8000 * 14.0 6.5 10.0 10.8 10.0 6.3 0.3 7.0 8.6 5.9 7.6 2.1 8000 + 8.6 7.6 6.1 . 7.9 8.1 8.6 0.8 3.9 5.9 3.5 . 7.0 2.1 12000* 5.3 3.6 5.3 9.1 3.3 9.6 0.3 1 .9 3.5 2.4 6.1 3.9. 1 2 0 0 0 + 3.4 8.0 -1 .6 4.5 0.1 3.8 0.9 4.0 0.7 2.1 5.1 2.0 STAND 1 STAND 2 STAND 3 STAND 4 Av. S.D. Av. S.D. FREQ. WIN. SUM. WIN. SUM. WIN, SUM'. WIN. e SUM. WINTER •SUMMER * 125 7.8 8.6 6.8 4.1 7.8 7.6 4.1 7.1 6.6 1 .8 6.9 1 .9 1 2 5 + 6.3 10.4 4.8 6.9 6.6 15.4 2.1 9.1 4.9 2.1 10.4 3.6 * 250 15.9 16.5 13.7 17.0 16.7 18.5 17.2 20.5 15.9 1 .6 18.1 1 .8 250 + 13.4 17.4 13.2 16.6 14.4 21 .6 10.9 19.4 13.0 1.5 18.8 2.2 * 500. 2.8 5.4 7.8 5.1 4.8 4.6 9.8 5.1 6.3 3.1 5.1 0.3 500 + . 4.3 6.3 7.3 5.3 4.3 6 . 3 5.0 6.3 5.2 T.4 5.8 0.5 1000* -1 .5 6.6 1 .3 10.4 -3 .5 5.4 . - 2 . 3 3.1 -1 .5 2.0 . 6.9 2.4 1000 + 2.8 7.8 5.3 8.5 . 0.5 5.0 2.3 5.8) ' 2.7 2 . 0 : 6.8 1 .6 2000* . 2 . 1 1 .4 3.4 3.1 3.1 -0 .6 -1 .4 r-0.1 1 .8 2.2 0.9 1 .7 2000 + 4.0 3.4 4.0 4.4 6.3 1 .1 1.0 - 3 .6 3.8 2. 2 1 .3 3.6 4000 * • 6.1 3.6. T.4 3.9 -1 .6 - 0 . 4 • - 0 . 6 3.6 1 .3 3,4 2.7 2.1 4000 + : 10.4 -1 .6 4.4 1 .6 1 .6 -1 .4 0.4 3,6 4.3 4.7 0.6 2.5 8000* : 1.1 6 . 6 - 0 .4 11 .4 - 0 .4 11 .9 - 7 . 7 5.9 - 1 . 9 3.9 8.9 3.1 800.0 + 6 .8 13.8 4.8 13.3 4-1 11 .8 - 0 . 2 13.0 3-9, 3.0 12.9 0.9 12000* 0.9 2.5 0.9 - 2 . 8 -1 .1 5.8 0.9 1.0 0.4 1 .0 1 .6 3.5 12000 + 1 .4 5.8 1 .4 1 .5 -0 .4 2.0 0.4 5.3 0.7 0 ,9 3.6 2.2 APPENDIX 5 B l a c k and White Photograph 's of the Tree Stands Douglas f i r 1 Douglas f i r 3 Mixture 1 Mixture 2 Alder 1 Alder 5 B i r c h 3 BIBLIOGRAPHY A n d e r s o n , C h a r l e s R. "Methods of No i se A b a t e m e n t , " 6„t.h Western Canad ian Roads ide Development C o n f e r e n c e , U .B .C . , Vancouve r , B.C. , June 1969, 13pp. Anon. " N o i s e P o l l u t i o n , " Ma s s a chu se t t s Audubon N e w s l e t t e r , V o l , 7 , No. 8, A p r i l 1968, 3pp. Anon. " F e d e r a l R e g u l a t i o n of A i r T r a n s p o r t a t i o n and the E n v i r o n m e n t a l Impact P r o b l e m , " The U n i v e r s i t y of  Ch i cago Law Rev iew, V o l . 35:317",' 1 968 , 25pp. A n t h r o p , Donald F. " E n v i r o n m e n t a l No i se P o l l u t i o n : A New T h r e a t to S a n i t y , " B u l l e t i n of the Atomic  S c i e n t i s t s , V o l . 25^No. 5, May 1 969 , 5pp. ' B a r r o n , Kenneth E. "Notes on Types o f Sound, R e l a t e d Sources and the Measurement of Sound , " 6th Western  Canad ian Roads ide Development C o n f e r e n c e , U .B .C . , Vancouver ' , ' B .C . June 1 969 , 8pp. B j e r r i n g , J . H . , Dempster , J . R . H . , and H a l l , R.H. U . B. C. T r i p , U n i v e r s i t y of B r i t i s h Co lumbia Computing C e n t r e , Feb rua r y 1969. B o n v a l l e t , G.L. " L e v e l s and S p e c t r a of T r a f f i c , I n d u s t r i a l and R e s i d e n t i a l Area N o i s e , The J o u r n a l o f the  A c o u s t i c a l S o c i e t y of A m e r i c a , V o l . 23 , No. 4 . , J u l y 1951. B ragdon , C l i f f o r d , R. " N o i s e - A Syndrome o f Modern S o c i e t y , " S c i e n t i s t and C i t i z e n , March 1968, 9pp. B u r r i s , Howard T. "An Approach f o r Qu i e t ' Ne ighbourhood P l a n n i n g , " Sound, V o l . 1, No. 5, September/ Oc tobe r 1962, 6pp. C a r p e n t e r , A. " E f f e c t s of No i se on Pe r fo rmance , and. P r o d u c -t i v i t y , " N a t i o n a l P h y s i c s Lab. Symposium #12, 1962, 13pp. Committee on the Prob lem of N o i s e , N o i s e : F i n a l R e p o r t , London, HMSO 1963. Cook, Dav id I. & Van Have rbeke , Dav id F. " T r ee s May Help S o l v e the T r a f f i c No i se P r o b l e m , " U n i v e r s i t y of  Nebraska Q u a r t e r l y , 1 6 ( 2 ) : 1969, 2pp. Durk , P. " D i e Bedeutung des Waldes f u r d i e E r ho l ung der B e v o l k e r u n g , " Der F o r s t and H o l z w i r t , V o l . 20, No. 10, May 1965, 3pp. E m b l e t o n , T.F.W. "Sound P r o p a g a t i o n i n Homogenous Dec iduous and Eve rg reen Woods," The J o u r n a l  o f the A c o u s t i c a l S o c i e t y of A m e r i c a , V o l . 35 , No. 8, August 1963, 7pp. E m b l e t o n , T.F.W. & T h i e s s e n , G . J . " T r a i n Noises, and Use of A d j a c e n t L a n d , " Sound - I t s Uses and C o n t r o l , J a n u a r y / F e b r u a r y 1962, 7pp. E m b l e t o n , T . F .W. , Dagg, I.R.-& T h i e s s e n , G . J . " E f f e c t o f Env i ronment on No i se C o n t r o l , " Noi se C o n t r o l , V o l . 5, No. 6, November 1959, 4pp. E y e r i n g , C .F . " J u n g l e A c o u s t i c s , " The J o u r n a l of the ' A c o u s t i c a l S o c i e t y of A m e r i c a , V o l . 18, No. 2, ' . . Oc tobe r 1946, 14pp. G a l l o w a y , C l a r k , e_t. al_. Highway N o i s e : Measurement S i m u l a t i o n and Mixed R e a c t i o n , Highway Research B o a r d , Wash ington D . C , 1 969 , 77pp. Gene ra l Rad io Company. Handbook f o r Sound L e v e l Meter  Type 1551-B, Gene ra l R a d i o , 1958. Gene ra l Rad io Company. Handbook f o r Sound L e v e l Meter  Type 1 565-A,. Gene ra l R a d i o , 1 966. Hess , W. & K u r s t e i n e r , E. " G r u n d s a t z i c h i e s zu r des V e r k e h r s l arms m i t H i . l f e von Grunpf 1 anzungen , " S c h w e i t z e r i s c h e Z e i t s c h r i f t f u r F o r s t w e s e n , V o l . 112, N o ' s . 10/11, 1961 , 9pp. H o r n i g , D.F. No i se - Sound W i thou t V a l u e , Repor t - Committee on E n v i r . Qual . of the F e d e r a l C o u n c i l f o r S c i e n c e and T e c h . , U.S. Government P r i n t i n g O f f i c e , Wa sh i n g ton , 1968, 56 pp. Hosey A.D. & P o w e l l . I n d u s t r i a l N o i s e : A Guide to E v a l u a -t i o n and C o n t r o l , , U . S . Government P r i n t i n g O f f i c e Washi ngton , D . C. , 1 967. Humphreys, H.R. "An A c o u s t i c a l C o n s u l t a n t ' s Ca sebook , " N a t i o n a l P h y s i c s Lab. Symposium #12, 1962, 9pp. K r y t e r , K a r l , D. "The E f f e c t s of No i se on Man, " The  J o u r n a l of Speech and Hea r i n g D i s o r d e r s , Monograph Supplement #1, 1950, 95pp. O t t , R. Have Your Heard? Nor thwes t Hardwoods A s s o c i a t i o n C o n f e r e n c e , Vancouve r , 1970. P a r k i n , P.H. " P r o p a g a t i o n of Sound i n A i r , " N a t i o n a l  P h y s i c s Lab. Symposium #12, 1962 , .15pp. R o b i n e t t e , Gary 0. "The F u n c t i o n a l Spectrum of P l a n t s . -No i se C o n t r o l , " Grounds M a i n t e n a n c e , V o l . 4, No. 8, August 1 969 , 2pp.. R o b i n s o n , D.W. " G e n e r a l Prob lems of the C o n t r o l of N o i s e , " N a t i o n a l P h y s i c s Lab. Symposium #12, 1962, 13pp. S a t a l o r f , J & Zapp, J . A . "The Env i ronment i n R e l a t i o n to O t o l o g i c D i s e a s e , " A r c h i e v e s of E n v i r o n m e n t a l  H e a l t h , V o l . 10, No. 3, March 1 965. S c h a f e r , R.M. "The C i t y as a Son i c Sewer , " Vancouver  Sun, March 1 1 t h , 1 969. S c h e n k e r - S p r u n g l i , 0 . "Down w i th - D e c i b e l s , " UNESCO - C o u r i e r , J u l y 1967, 3pp. S t e p h e n s , R.W.B. and B a t e , A . E . A c o u s t i c s and V i b r a t i o n a l  Phys i c s , London, 1966, 818pp. S u g i h a r a , H. & K i t a y a m a , S. " N o i s e of Wood Work ing M a c h i n e r y , " Mokuzai Kenkyu, No. 39, 1966, 6pp. Sw ieboda , M a r i a . " P r ob l ems of No i se and P r o t e c t i o n of N a t u r e , " Chronmy P r z y r o d e O j i z y s t a , Vo1. 22, No. 1 , 1 966, 9pp. Watson, F.R. Sound, J . W i l ey .& Sons, New Yo r k , 1 935 , 219pp. Welch , Bruce L. "SST: Coming Th rea t to W i l d e r n e s s , " N a t i o n a l Parks Magaz i ne , March 1968, 3pp. We l ch , B.L. " P h y s i o l o g i c a l E f f e c t s of A u d i b l e S o u n d , " , S c i e n c e , V o l . 166, 24th Oc tober 1969, 3pp. W iene r , F.M. & K e a s t , D.N. " E x p e r i m e n t a l Study of the P r o p a g a t i o n of Sound over G r o u n d , " The J o u r n a l  of the A c o u s t i c a l S o c i e t y of A m e r i c a , V o l . 3 1 , No. 6, June 19 59, 10pp. Z u n d e l , R.. " L u f t f i 1 t e r u n g und Larmdampfung durch S t r a s s e n b e g l e i t p f 1 azungen , " Der F o r s t u.nd  H o i z w i r t , Nr. 10, 23rd May 1 965 , 2pp. 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            data-media="{[{embed.selectedMedia}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0101911/manifest

Comment

Related Items