An Experimental assessment of the CSA Standard on ' Measurement and rating of the noise output of consumer appliances'

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An Experimental assessment of the CSA Standard on ' Measurement

and rating of the noise output of consumer appliances'

Trepanier, J.-Y.; Chu, W. T.

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AN EXPERIMENTAL ASSESSMENT OF THE CSA STANDARD ON 'MEASUREMENT AND RATING OF THE NOISE OUTPUT ON CONSUMER APPLIANCES'

by J-Y. Trepanier and W.T. Chu

Reprinted from Canadian Acoustics

Vol. 13, No. 1, January 1985 p. 3 - 6

DBR Paper No. 1259

Division of Building Research

T h i s p a p e r , w h i l e b e i n g d i s t r i b u t e d i n r e p r i n t form by t h e D i v i s i o n of B u i l d i n g R e s e a r c h , remains t h e c o p y r i g h t of t h e o r i g i n a l p u b l i s h e r . It s h o u l d n o t be r e p r o d u c e d i n whole o r i n p a r t w i t h o u t t h e p e r m i s s i o n of t h e p u b l i s h e r . A l i s t of a l l p u b l i c a t i o n s a v a i l a b l e from t h e D i v i s i o n may be o b t a i n e d by w r i t i n g t o t h e P u b l i c a t i o n s S e c t i o n , D i v i s i o n of B u i l d i n g R e s e a r c h , N a t i o n a l R e s e a r c h C o u n c i l of C a n a d a , O t t a w a , O n t a r i o , KIA OR6.

AN EXPERIMENTAL ASSESSMENT OF THE CSA STANDARD O N

'MEASUREMENT AND RATING OF THE NOISE OUTPUT OF CONSUMER APPLIANCES' Jean-Yves T r e p a n i e r S t u d e n t I h i v e r s i t y of Sherbrooke W.T. Chu N a t i o n a l R e s e a r c h C o u n c i l Canada D i v i s i o n of B u i l d i n g Research

Ottawa, Canada K1A OR6

ABSTRACT

The n o i s e o u t p u t of f i v e s m a l l sound s o u r c e s h a s been measured u s i n g t h r e e d i f f e r e n t methods s u g g e s t e d by t h e CSA s t a n d a r d

2107.71-M1981. R e s u l t s i n d i c a t e t h e y can produce c o n s i s t e n t answers.

Le b r u i t p r o d u i t p a r c i n q s o u r c e s s o n o r e s a d t 6 mesur6 s e l o n t r o i s m6thodes recommand'ees p a r l a norme 2107.71-Ml981 d e

l l A s s o c i a t i o n c a n a d i e n n e de n o r m a l i s a t i o n . Les donndes o b t e n u e s i n d i q u e n t q u e c e s mgthodes f o u r n i s s e n t d e s r ' e s u l t a t s s e n s i b l e m e n t u n i f ormes.

INTRODUCTION

T h i s work was u n d e r t a k e n t o p r o v i d e a d d i t i o n a l e x p e r i m e n t a l s u p p o r t t o t h e CSA s t a n d a r d on 'Measurement and R a t i n g of t h e Noise Output o f Consumer Appliances.' Four s m a l l a p p l i a n c e s and a s t a n d a r d ILG s o u r c e were t e s t e d a c c o r d i n g t o t h e t h r e e

d i f f e r e n t methods s u g g e s t e d by t h e CSA s t a n d a r d . Although t h e n o i s e o u t p u t of some of t h e s o u r c e s had been measured b e f o r e , l t h e y were r e t e s t e d h e r e t o form a complete s e t . No a t t e m p t h a s been made t o compare t h e p r e s e n t r e s u l t s w i t h t h o s e of Ref. 1 s i n c e t h e o p e r a t i n g c o n d i t i o n s of t h e a p p l i a n c e s might n o t have been t h e same.

SOURCES

The s o u r c e s and t h e i r o p e r a t i n g c o n d i t i o n s chosen f o r t h e p r e s e n t e x p e r i m e n t a r e :

1 ) a s t a n d a r d ILG s o u r c e ;

2) a s m a l l blower o p e r a t e d a t maximm speed;

3 ) a h e a t gun set i n t h e ' c o l d ' p o s i t i o n w i t h t h e a i r e n t r y p o r t s e t a t maximum opening;

4 ) a f i x e d s p e e d hand d r i l l ; and

5 ) a b l e n d e r f i l l e d w i t h 680 g (24 oz) of w a t e r and o p e r a t e d a t t h r e e d i f f e r e n t s p e e d s , No. 1 ( s l o w e s t ) , No. 7 (medium), and No. 1 4 (maximum).

Although t h e s e s o u r c e s r e p r e s e n t o n l y a s m a l l c r o s s s e c t i o n of consumer

a p p l i a n c e s , i t i s hoped t h a t t h e i r c h a r a c t e r i s t i c s a r e d i f f e r e n t enough t o p r o v i d e a r e a s o n a b l y good t e s t of t h e t h r e e methods of t h e s t a n d a r d . The o n e t h i r d o c t a v e power s p e c t r a of t h e s e s o u r c e s were measured i n a r e v e r b e r a t i o n room and a r e p r e s e n t e d i n Fig. 1. 4 0 -

-

F i g u r e 1. One-third o c t a v e band sound power l e v e l s of t h e d i f f e r e n t s o u r c e s u s e d i n t h e experiment.

METHODS

The n o i s e o u t p u t f o r e a c h of t h e s o u r c e s l i s t e d above was measured w i t h t h e s o u r c e s i t t i n g on a h a r d s u r f a c e u s i n g t h e f o l l o w i n g methods.

( 1 ) E k v e r b e r a t i o n Room Method:

The measurements were conducted a c c o r d i n g t o ANSI S t a n d a r d S1.31-1980 i n a r e v e r b e r a t i o n chamber w i t h a nominal volume of 255 m3 and dimensions o f

8.0 x 6.5 x 4.9 m. The room i s equipped w i t h f i x e d d i f f u s e r s and a r o t a t i n g vane. I t h a s a u t o m a t i c e n v i r o n m e n t a l c o n t r o l s and i s g e n e r a l l y m a i n t a i n e d a t 21°C and 55% r e l a t i v e humidity.

The sound f i e l d was sampled by n i n e microphones l o c a t e d randomly i n t h e room and t h e s o u r c e s were t e s t e d a t t h r e e d i f f e r e n t l o c a t i o n s on t h e f l o o r . The b a s i c d a t a o b t a i n e d by t h i s t e s t were sound power l e v e l s f o r a series of o n e - t h i r d o c t a v e

f r e q u e n c y bands from 1 0 0 t o 1 0 , 0 0 0 Hz. These were t h e n added w i t h p r o p e r A-weighting c o r r e c t i o n s t o produce t h e A-weighted sound power l e v e l s . A more d e t a i l e d d e s c r i p t i o n o f t h e i n s t r u m e n t a t i o n u s e d can b e found i n Ref. 2.

( 2 ) F r e e F i e l d Method:

The measurements were made o u t d o o r s i n an open f i e l d w i t h t h e n e a r e s t b u i l d i n g a t l e a s t 100 m away. The r e f l e c t i n g f l o o r was a p a i n t e d 2.4 x 2.4 m wood p a n e l w i t h a 38 mm t h i c k n e s s . Two measuring r a d i i of 0.75 and 1 m were used. Except f o r t h e ILG s o u r c e and t h e h e a t gun, t h e f o u r recommended measuring l o c a t i o n s were found t o b e q u i t e adequate. The A-weighted sound p r e s s u r e l e v e l s were measured d i r e c t l y w i t h a

B&K

windscreen; t h i s combination o f f e r s a f l a t f r e q u e n c y r e s p o n s e f o r f r e e f i e l d measurement a t O0 a n g l e of i n c i d e n c e . The i n t e g r a t i o n t i m e u s e d was 3.6 s. The i n s t r u m e n t was c a l i b r a t e d w i t h a B&K Type 4230 c a l i b r a t o r b o t h b e f o r e and a f t e r e a c h

t e s t .

( 3 ) P a r t i a l l y A b s o r p t i v e Room Method:

For t h i s c a s e , a 122 m3 r e v e r b e r a t i o n room was c o n v e r t e d i n t o a p a r t i a l l y

a b s o r p t i v e room by a d d i n g a b s o r p t i o n t o meet t h e r e q u i r e m e n t t h a t A / R ~ be g r e a t e r t h a n 20. R i s t h e measurement r a d i u s and A i s t h e sound a b s o r p t i o n of t h e t e s t room

d e t e r m i n e d from r e v e r b e r a t i o n t i m e measurements. Two v a l u e s of A , 19.1 and

27.8 m e t r i c s a b i n s , were used. A s i n method ( 2 ) , two measuring r a d i i were u s e d w i t h t h e same p o s i t i o n s a r o u n d t h e s o u r c e s . The A-weighted sound p r e s s u r e l e v e l s were a l s o t a k e n w i t h t h e B&K Type 2218 sound l e v e l meter.

RESULTS AND DISCUSSION

For comparison p u r p o s e s , t h e r e s u l t s o b t a i n e d by t h e t h r e e d i f f e r e n t methods h a v e been c o n v e r t e d t o sound l e v e l r a t i n g s f o r i n d o o r u s a g e a s s p e c i f i e d i n CSA 2107.71. These a r e p r e s e n t e d i n Table 1.

Although t h e r e v e r b e r a t i o n room method t e n d s t o g i v e h i g h e r v a l u e s f o r most of t h e s o u r c e s t e s t e d , t h e d i f f e r e n c e s a r e n o t l a r g e and c a s t n o s e r i o u s d o u b t s on t h e v a l i d i t y of t h e t h r e e methods used. It i s hoped t h a t t h i s e x c e r c i s e w i l l g i v e

m a n u f a c t u r e r s c o n f i d e n c e i n a d o p t i n g any o n e of t h e s e methods f o r measuring t h e n o i s e o u t p u t and r a t i n g t h e i r products.

TABLE 1

Comparison of Sound Level R a t i n g s (dBA) of D i f f e r e n t Sources Obtained by t h e T h r e e Methods

P a r t i a l l y A b s o r p t i v e Room Free-Field

Measurements A = 19.1 A = 27.8 Noise R e v e r b e r a t i o n

S o u r c e s Ro om R=.75 R=l.O R=.75 R=l.O Rz.75 R=l.O

ILG 86.5 87.3 87.2 86.5 86.2 86.6 86.5 Small Blower 83.0 82.2 82.3 82.8 82.9 82.7 82.9 Heat Gun 77.0 77.5 77.3 76.6 76.5 77.0 77.4 Hand D r i l l Blender Speed /I1 75.5 73.5 73.4 73.0 73.6 74.5 74.0 Blender Speed /I7 81.5 80.8 81.0 79.8 79.9 79.3 79.0 Blender Speed 814 85.5 84.9 84.9 84.3 84.7 84.8 84.3 REFERENCES

( 1 ) T.D. Northwood and W.T. Chu, "Measurement of Sound Emission of Small Sources i n R e v e r b e r a n t and Anechoic Environments," p r e s e n t e d a t t h e Canadian A c o u s t i c a l A s s o c i a t i o n Annual Meeting a t Windsor, k t a r i o , 24-26 October 1979.

( 2 )

W.T.

Council of Canada," B u i l d i n g Research Note No. 203, D i v i s i o n of B u i l d i n g R e s e a r c h , N a t i o n a l Research Council Canada, May 1983.