Subjective rating of the sound insulation of party walls

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Subjective rating of the sound insulation of party walls

INTRODUCTION

For many y e a r s the D i v i s i o n of Building Research has s t u d i e d noise- r e l a t e d problems in b u i l d i n g s and the p r o p a g a t i o n of this n o i s e through

walls.

The r e s u l t s of t h i s work provide guidance to the construction

i n d u s t r y and t o government agencies such a s Canada Morrgage and

Rousing, and are a major source of i n p u t to the National B u i l d i n g Code.

Our overall understanding of t h e p h y s f c a l acoustical aspects of

sound isolation between d w e l l i n g s has gradually improved. For about 20

years the sound insulating properties of p a r t y walls have been measured in term of t h e i r sound transmission class (STC), and t h e N a t k o n a l Building code1 now speciffes that p a r t y walls should achieve a minimum

sound insulation of STC 4 5.

U n f o r t ~ ~ n a t e l y , very l i t t l e progress has been made concerning the human s i d e of the problem. The lack of extensive s t u d i e s and d a t a on human reactions to v a r i o u s l e v e l s of party-all sound i n s u l a t i o n has made i t difficult to verify the accuracy of STC in predicting such adverse reactions. For t h e same reason, it has n o t been p o s s i b l e to

d e t e d n e a satisfactory mi nirnum v a l u e of p a r t y - w a l l sound insulation,

or t o understand the i n t e r a c t i o n of t h e many factors t h a t i n f l u e n c e t h e reaction of residents to noises caused by their neighbours. Since sorrnd tnsulation of party w a l l s is solely for the benefit of p e o p l e , it is Fmpcrardve that researchers improve t h e i r undess t a n d i n g of how p e o p l e i n multi-residence b u i l d i n g s react t o n o i s e s from t h e i r neighbours.

A number of f i e l d surveys on t h e annoyance caused by various environmental n o i s e s such as road traffic noise have been carried o u t .2 More

recent

s t u d i e s using improved experimental t e c h n i q u e s have f o u n d q u i t e strong c o r r e l a t i o n s between i n d i v i d u a l responses and

a c o u s t i c a l measrlrements o f traffic noise l e v e l s . 3-6

It

was n o t c l e a r however, whether the methods used

in

the traffic n o i s e surveys

were

s u i t a b l e f a r a survey concernkg party-wall sound insulation, s t n c e

comparable prevlous studies were n o t available. (Data from t w o very recent unpublished studies have b e e n o b t a i n e d and are d i s c u s s e d later in t h i s r e p o r t . ) For example, it was not: known whether annoyance-type

r e s p o n s e s c o u l d be related to physical measures of sound insulation in a statfstically significant manner, o r whether the situation would be confused by other i n t e r v e n i n g variables. This n o t e describes t h e p i l o t

study undertaken to test the suitability of one proposed experimental approach,

To make the physical measurements as complete as possible, it was d e c i d e d to i n c l u d e both detailed 113 octave band measurements of sound

fnsularion as w e l l as at least one complete 24-hour record eE background noise levels in each home, The physical measurements were to be carried out a f t e r the related interviews were completed. As in p r e v i o u s traffic

n o i s e surveys, t h e i n i t i a l approach to each subject w a s designed to

o b t a i n the maximum cooperation, wlthout p o s s i b l y biasing responses by

exact purpose of the study. The subjective responses were to be

o b t a i n e d w i t h a s t r u c t u r e d q u e s t i o n n a i r e a d m i n i s t e r e d by a t r a i n e d

interviewer in each person's home. Results were o b t a i n e d Erom p a i r s of adjacent homes.

In

a l l , t h e r e s p o n s e s of 98 subjects were i n c l u d e d i n

the analyses, tagether with measurements o f the background noise . l e v e l s

in t h e 98 homes and t h e sound i n s u l a t i o n af t h e 49 common w a l l s .

F o r p r a c t i c a l reasons, i L was p o s s i b l e to consider o n l y one

ne5ghbour of each s u b j e c t , to measure only one common wall, and to

measure hackground levels at only one p o i n t during only one day. As t h e s e was n o p r e v i o u s information to i n d i c a t e whether disturbance d u e to

neighhours' noises was related to some p r o p e r t i e s of t h e wall, to n o i s e

l e v e l s in each home, or to a combination of these quantities, the p r o c e d u r e used should ideally have allowed the c o n s i d e r a t i o n of a l l p o s s i b l e variations. Unfortunately, f t was n o t p r a c t i c a l t o make more e x t e n s i v e measurements, due to the extra research e f f o r t r e q u i r e d , and

t o the d i f f i c u l . t y of finding large numbers of subjects willing to p e t d r

such dfsruption of their homes.

TI.

SURVEY PROCEDURE

1. General

S i n c e t h i s w a s only a p i l o t study, it was limited to 100 s u b j e c t s . To ensure t h a t such a small sample would allow a r e l i a b l e e v a l u a t i o n of t h e proposed techniques, it was essential t o include the widest p o s s i b l e

range of sound i n s u l a z i o n v a l u e s . To s i m p l i f y administrative p r o b l e m ,

only r e s i d e n t s l i v i n g tn condorntniurns were approached. A l o c a l

condominfum management company a s s i s t e d by suggestfng sites that might

have superior, average or i n f e r i o r quality sound i n s u l a t i o n . S u b j e c t s

were s e l e c t e d randomly in pairs from 11 different s i t e s . G e n e r a l l y , 10

s n b j e c t s ( 5 pairs of a d j a c e n t dwellings) were interviewed at each site,

b u t t h e r e were as f e w as 6 a n d as many as 1 2 interviews at some s i t e s .

S u b j e c t s were first contacted by means a £ a n i n t r o d u c t o r y L e t t e r stating that t h e y would be v i s i t e d by an i n t e r v i a e r Erom the Division of B u i l d i n g Research a t t h e N a t k o n a l Research Council who w a s c a r r y i n g

o u t a ' " B u i l d i n g Satisfaction Survey", The i n t e r v i e w s were carried o u t

using a structured qirestionnaire that is described in the fol2owing

section. F o l l o w i n g a successful i n t e r v i e w , the i n t e r v i e w e r asked i f t h e

s u b j e c t would permit sound insulation and background noise measurements

to be made. T f one of t h e a d j a c e n t ne-lghbours was a l s o s u c c e s s f u l l y CntervIewed and a l s o agreed t o permit noise and sound i n s u l a t i o n to be measured, then one complete pair of i n t e r d e w s from adjacent residences was o h t a l n e d and sorind fnsulatian measurements were made within a month a f t e r the I n t e r v i e w s .

The First Lnterview of each pair was selected r a n d o m l y f r o m s i t e

p l a n s . The person answering t h e door, if 1 8 years or o l d e r , was asked t n answer t h e questionnaire. Interviews were carried out both in t h e d a y t l ~ n e a n d t h e evening t o e n s u r e a reasonable b a l a n c e between male and

fernale r e s p o n d e n t s . Of the s u b j e c t s , 84% l i v e d i t 1 two-storey row h o u s i n g , while t h e r e m a i n d e r l i v e d i n a p a r t m e n t h l o c k s . This linevet1

spread between row housine and apartments was dellberate s i n c e thr

acoustically s i m p l e r case of row h o u s i n g was e x p e c t e d t o p r o d u c e s i g n i f i c a n t p r o b l e m s , while the more complex situation in a p a r t m e n t

h l o c k s was not c o n s i d e r e d s u i t a b l e for an i n i t i a l p i l o t s u r v e y , A few apartment condominiu~n r e s i d e n t s were included, however, t o give some

i n d i c a t i o n of t h e possible problems in t h a t t y p e of building.

t n a l l , 120 successful i n t e r v i e w s were o h t a i n e d which r e s u l t e d i n

9 8 s u b j e c t s for t h e f i n a l analyses. Of t h e o t h e r i n t e r v i e w s , 20 w e r e

unmatched Interviews; t h a t

is,

a successful interview with an a d j a c e n t

n e i g h b o u r could not o b t a i n e d . The 2 r e m a i n i n g i n t e r d e w s caurd n o t b e

used because one subject e v e n t u a l l y withdrew permission f o r the sound insulation measurements. b r i n g the i n t e r v i e w i n g stage, 27 s u b j e c t s declined to be interviewed and a f u r t h e r 6 s u b j e c t s d i d not meet the

requirements f o r subjects. I f one considers t h e 27 refusals as a

proportion of t h e 120 successful interviews, a response rate of 81% was o b t a i n e d .

On completion of t h e field measurements, a l l subjects received a

letter i n f o r m i n g them o f the average results f o r t h e i r condominium c o r p a r a t i o n , and thanking them for t h e i r assistance,

2. The Questionnaire

The questionnaire and coding tnformatkon is included i n Appendix A.

T h e f i r s t section of the questionnaire (Questtans 1 to

9)

c o n t a i n s open-

ended questions and some d i r e c t questions about the general desirability o f t h e b u i l d i n g i n which t h e subject l i v e s . Questions 10 a n d I 1 a s s e s s rhe n o t s i n e s s of h i s particular home a n d lifestyle, w h i l e w e s t i o n s 12

to 19 assess directly elicited annoyance to v a r i o u s r y p e s of n o i s e s .

The noises made by n e i g h h o u r s are considered separately f o r different s p a t i a l relationships w i t h i n the b u i l d i n g a n d f o r different t i m e s of

day. Also i n c l u d e d are questions t o determine which n o i s e s a r e

partfcularly annoying. Questions 2 0 and 2 1 concern t h e p o s s i b i l i t y of sleep disturbance due to n o i s e and are followed by Q u e s t i o n 2 2 , which is

a n a t t e q t to measure t h e p e r c e i v e d annoyance in terms of a r e a d i l y

understood o b j e c t i v e c o s t . Questions 23 to 2 8 gather demographic and

other d a t a that may c o n t r i b u t e t o understanding annoyance r e s p o n s e s . The l a s t page of the questtonnaire c o n t a i n s Spellbergerrs measure of

t r a i t anxiety7 which i n p r e v i o u s s t u d i e s of annoyance due to n o ~ s e ~ - ~

,'

h a s been f o u n d t r 3 cant rithlte to annoyance r e s p o n s e s .

Most responses were obtained u s i n g seven-point response scales w i t h o n l y

the extremes and t h e mid-pofnrs labelled. These were L a b e l l - e d " n o t a t a l l , " "medium" and "extremely." T h i s procedure had b e e n found TO be

s u c c e s s f u l i n t h e p a s t i n p r o v i d i n g a p p r o p r i a t e i n t e r v a l s c a l e d a t a , a n d

was lised agaln here w t t h only a minor change to one of the labels t o

The questlnnnaire was pretested on s u b j e c t s w o r k i n g L n the D t v i s i o n

o f

B u i l d i n g Reseat-ch. To ensure a realistic t e s t , p r e t e s t s u b j e c t s were selected who I t v e d in multiple-residence b u i l d i n g s and had no t e c l r n l c a l

k n m l e d g e of any p r e v f nus a c o u s t f c a l s t u d i e s .

A total of 98 v a r i a b l e s per subject were entered into the Final data f i l e of which 30

were

n o i s e or s o u n d insulation measures. Survey responses were entered d t r e c t l y i n t o a mini-computer u s f n g a program t h a t promp Led t h e u s e r w i t h q u e s t i o n s f r o m t h e q u e s tlannaire. Avoiding the i n t e r m e i l k a t e step a€ codlng sheets thus eliminated t h e passibtlity

of

errors in

transcription.

3. Noise and Sound Insulation Measures

In each home one complete 26-hour record of normal background n o i s e

l e v e l s was o b t a i n e d u s t n g a miniature d e v i c e that s tored a n A-weigh ted

%(2 value (energy equivalent sound l e v e l ) digitally f o r each three- m l n u t e p e r i o d of a complete 24-hour day (Metrosonics ?letrnlogger dB-

301). from these 480 L v a l u e s , a daytime ( 7 ~ 0 0 a . m . to 10:00 p . m . ) , EQ

a n i g h t t i m e (10.00 p.m. to 7 : 0 0 a . m . ) and a complete 24-hour L v a l u e

were calculated. 'Chese are referred to as L D _{EQ * ~ - E Q}

'

and LEQ 'Q24

,

sespectfvely, in t h i s reporr. Each subject's d a t a in the final d a t a f i l e c o n t a i n e d t h e three L values f o r b o t h h i s home and h i s

Erl

n e l g h b o u r ' s . S i n c e t h e homes w e r e a l l o c c u p i e d a n d t h e occupants

frequently I n c l u d e d small children, t h e LEq measuring d e v t c e s had to be pnsttioned in Incations where they were least likely t o be disturbed r a t h e r t h a n i n acoustically optimum p o s i t f o n s . Thus, they were u s u a l l y

p l a c e d on shelves or on t o p o f c a b i n e t s t n the Living room of each home, T h e m i c r o p h o n e was g e n e r a l l y c l o s e t a a wall o r large r e f l e c t i n g p i e c e of f u r n i t u r e .

To n l n i r n i z e the inconvenience t o subjects, the t e s t sounds were

tape recorded i n t h e h a w s and then analyzed in t h e laboratory w i t h a computer. When perfected, t h i s technique allowed the c o m p l e t e sound

t r a n s m i s s i o n loss measurements i n v o l v i n g measurements in two a d j a c e n t

homes to be completed in

20

minutes.

I n

a number of c a s e s a more t i m e - consuming procedure s i m p l y would n o t have been t o l e r a t e d .

Using a conventional pink noise source and a FH instrumentatLon tape recorder, sounds were r e c o r d e d for three 16-second b u r s t s i n b o t h

the receiving and source rooms. A manually rotated microphone boom was

u s e d to average t h e sound l e v e l s f o r each room.

In

t h e s i d e s e l e c t e d a s

t h e receiving room, hackground nofse l e v e l s , as w e l l a s f i v e sound decays, were a l s o recorded, a g a i n u s i n g a pink n o l s e source. When recording the r e c e i v i n g room levels, in which the spectrum was s t r o n g l y tnfluenced by t h e t y p i c a l sound transmission l o s s p r o p e r t i e s of w a l l s ,

t h e sfgnal was f i r s t filtered to provide a f l a t t e r spectrum and t h e r e b y

to o p t i m i z e the use of t h e d y n a d c range of t h e tape recorder. An

i n v e r s e filter w a s then tised when playfng back t h e sound. The tape

digital converter i n t e r f a c e d t o the integrated (RMS] o u t p u t s of a

p a r a l l e l s e t of 1/3 o c t a v e f i l t e r s . Ry a v e r a g i n g the s a m p l e d s o u n d

l e v e l s i n each 11'3 octave band from 100 to 4000 llz over t h e time

required f o r the microphone t o r o t a t e , roowaveraged sound l e v e l s were

p r o d u c e d for the two cases t h a t used the p i n k noise source, as well a s

f o r the background n o i s e l e v e l s . The average of t h e sound decays

in

each 113 o c t a v e band was displayed oa a computer graphics t e r m i n a l . The o p e r a t o r t h e n selected the portion of t h e curve to whlch a s t r a i g h t l i n e was t o be fitted for calculating the reverberation t i m e

I n

the r e c e i v i n g room. This avoided any possibility of including the e f f e c t s of

background noise l e v e l s in the calculation of reverberatlon times.

The sound transmission loss

(TL)

was calculated in each IJR o c t a v o band, from 100 to 4000 Hz, u s i n g t h e relationship:

-

-

where SPLS, SPLR are the space-averaged sound pressure l e v e l s I n the source and receiving room respectively, S is the area o f t h e common

wall and AR 5s the total sound absorprion in the r e c e i v i n g room c a l n ~ l a t e d f r o m t h e Sabine reverberation e q u a t i o n as

where

V

is the room volume of the receiving room and TbO, t h e measured reverberation time.

From the information for each 113 octave, several single-oumber

r a t i n g s o f t h e a i r b o r n e sound i s o l a t i o n were c a l c u l a t e d . The sound

transmission c l a s s (STC) was calculared from the El3 octave STI, v a l u e s f r o m 125 t o 4000 Hz according t o t h e standard procedure ASTM ~ 4 1 3 . ~ ~

The noise isolation class

(NIC) was

c a l c u l a t e d as well usFng the ASTM

E59b

procedure.

'

I n addition, s e v e r a l A-weighted single-number measures were c a l c u l a t e d which, although not standardized quanrlties, are extremely s f m i l a r t o the

ASTM

E597 procedure.1Z

Since some of the A-weighted measures depend on t h e s o u r c e

spectrum, t h e s o u r c e room levels were f l r s t c o r r e c t e d by e s t a b l i s h i n g

equal l e v e l s in each 1/3 actave band so that the source room spectrum

was e x a c t l y pink in nature. The same c e r r e c t i o n s were then a d d e d to t h e corresponding 113 o c t a v e sound l e v e l s in the r e c e i v i n g room, Four of

t h e f i v e measures calculated were a form of A-weighted l e v e l d i f f e r e n c e and would therefore be i n f l u e n c e d by the source spectrum. The exception

was a n A-weighted transmission loss sum g i v e n as Eollaws:

en,+

w,

1/10

STA = -10 l o g

{

-

L

f 7 10

1

TLi are the individual 113 octave sound transmission l o s s values

o b t a i n e d a s in equation ( 1 ) above; Wi are t h e attenuations in d e c i h e l s

of the A-weighting curve a t the 113 o c t a v e band c e n t r e frequencies. The

STA

values are positive and very s i m i l a r

i n

magnitude to the corresponding

STC

values.

Four A-weighted

difference in

levels-type measures were c a l c u l a t e d and given t h e symbols 136, DAS, OAN, DANS. The f itst, DA, was s i m p l y t h e

difference in o v e r a l l A-weighted l e v e l s measured a f t e r t h e s o u r c e was corrected to be p e r f e c t l y p i n k . The second, DAS, was an A-weighted difference in o v e r a l l l e v e l s between t h e source and r e c e i v i n g rooms

a f t e r the s o u r c e had been c o r r e c t e d to t h e source spectrum proposed by Schultz. This Schultz source spectrum is i n c l u d e d in the ASTM E597

procedure.12 Two other measures included a normalization that

compensated for v a r i a t i o n s i n common wall area and r e c e f v i n g room

a b s o r p t i o n . Thus, before t h e A-weighted d i f f e r e n c e s f o r each 113 o c t a v e

band were summed up, they were normalized by an addition of -10 l o g

( S / A ~ )

(where Al is t h e i n d i v i d u a l 1/3 o c t a v e band r e c e f v i n g room

a b s o r p t i o n ) , N o r m l i z e d A-weighted differences c a l c u l a t e d w i t h a pink

s o u r c e spectrum were given the symbol

DAN,

and t h o s e calculated w i t h the Schultz source spectrum were g i v e n t h e

symbol

DANS.

Lri t h e analysis of the results a further n o i s e m e a s u r e , the B r i t i s h aggregate adverse deviation

(AAD)

,

was a l s o c a l c u l a t e d ( e . g .

,

s e e

Ref. 1 3 ) . 731s measure is t h e sum of a l l deviations below a reference c o n t o u r and thus ignores

all

bands where the measured p e r f o r m n c e is superior to t h e performance standard contour.

4 . Analysis

Roth the survey response data and the noise and sound Insulation data were i n i t i a l l y processed on a tnini-computer. A final combined d a t a f i l e was created w i t h 98 variables f o r each s n b j e c t as d e t a l l e d in

Appendlx A. The combined d a t a file was t h e n t r a n s f e r r e d to the NRC

IBM 370 computer and s t a t i s t i c a l a n a l y s e s w e r e carried out using t h e S t a t i s t i c a l Package for Social Sciences ( S P S S ) , Release 8.1.

I RESULTS

I.

Characteristics of the Survey Samafe

S i n c e the sample in t h f s pilot s t u d y is q u i t e small (98 s u b j e c t s ) , survey responses should be considered w i t h reference to t h e p a r t i c u l a r

acoris tPcal csndi tions t o

whlch

they relate and not as g e n e r a l l y

representative of some larger p o p u l a t i o n .

In

Table I, which summarixes measured noise l e v e l s and single-number sound i n s u l a t i o n v a l u e s , the mean v a l u e and s t a n d a r d d e v i a t f o n aboat the mean is given for each quantfty. It is seen that the mean 24-hour Td in the homes measured

EQ

sound transmission c l a s s (STC) is shown in T a b l e Z to be 51.2 dB. The complete d i s t r i b u t i o n of measured STC values, t l l t ~ s t r a t e d i n Figure I ,

ranges from 39 t o 60 dB. F i g u r e 2 presents the mean v a l u e s and s t a t ~ d a r d deviation of t h e measured 113 octave s o u n d t r a n s m i s s i o n loss (TL)

v a l u e s .

It

is seen t h a t these data

do

represent a quite w i d e range o f

party-wall sound insulation v a l n e s In t e r n o f the STC. S i n c e one w o u l d

not expect to find significant numbers of walls with STC values outside

t h e range i n c l u d e d h e r e , t h e s e d a t a s h o u l d thus be r e p r e s e n t a t i v e of

most r e a l i s t i c party-wall sound i n s u l a t i o n v a l u e s . Unfortunately, t h e r e

i s a perhaps i n e v i t a b l e concentration of STC v a l u e s In the range STC 46

-

54

whfch i n c l u d e s 69% of the d a t a .

A summary oE t h e b a s i c dernographlc information f o r t h e 98 s u b j e c t s of t h i s s t u d y 1s f o u n d in T a b l e 11. The s p l i t between males a n d females

was nearly equal and q u i r e satisfactory for studying p o s s i b l e e f f e c t s

d u e t o t h e respondents' sex. It w o u l d a p p e a r t h a t mast r e s p o n d e n t s were away from home d u r i n g the day and p r o b a b l y worked full-time, w h l l e a smaller number worked in t h e evenings o r at n i g h t and w e r e u s u a l l y hone d u r i n g the day. Since the residences were a l l condominiums, most

s u b j e c t s (91.82) were a l s o the owners of the home.

T a b l e LIP summarizes the ownership and use of various potenttally n o i s e - p r o d u c i n g d e v i c e s .

On

average, r a d i o s and t e l e v i s i o n s we r e found

t o be u s e d many more hours per week t h a n s t e r e o equipment. It should b~

n o t e d t h a t t h e range o f t h e s e values as reflected by t h e s t a n d a r d

d e v i a t i o n s ts quite large; there i s thus considerable v a r i a b i l i t y among the subjects

In

t h e use sf t h e s e three types ef d e v i c e s , T a b l e

I11 a l s o lists the percentages of s u b j e c t s owning various n o i s e -

producing a p p l i a n c e s -

Annoyance responses ate f r e q u e n t l y examfned by considering the

p r o p o r t i o n of respondents who a r e very annoyed by v a r i o u s n o i s e s . Because there were only 98 subjects in all, the number of subjects falling i n t o t h i s extreme c a t e g o r y w a s g e n e r a l l y too s m a l l to p r o v i d e r e l i a b l e r e s u l t s . For t h i s reason, t h e annoyance responses were flrst emmined i n t e r m of the percentage of s u b j e c t s who were annoyed t o any

degree. Thus, T a b l e IV shows the percentage of subjects s c o r i n g g r e a t e r t h a n 1 on various response s c a l e s . From T a b l e IV i t is seen t h a t more

than half of t h e subjects were annoyed by noises from neighbours on

e i t h e r s i d e of them, by t r a f f i c noise and by other ourdoat nolses. C l e a r l y , the problem of annoyance due ta outdoor noises ( i n c l u d i n g

traffic n o i s e ) was at l e a s t as severe a s t h e probLern of d i s t u r b a n c e or annoyance due to n o t s e s from their neighbours. Plumbing n o i s e s ,

b u i l d i n g m c h i n e z y noises, a i r c r a f t n o i s e s , neighbours' n o i s e s and doors slamming annoyed from 30 t o 34% of the respondents. Of course, t h e

percenLage annoyed by atrcraf t noFse would depend l a r g e l y on the

location of each home r e l a t i v e to a i r c r a f t f l i g h t paths- Annoyance d u e

to floor v i b r a t i o n s , noises from t o o l s and a p p l i a n c e s , a n d t e l e p h o n e

difficulty f a l l i n g asleep and were more o f t e n awakened by outdoor noises than by noises from t h e i r neighbours.

S u b j e c t s were asked whether there was any particular room i n which t h e y were mote annoyed by noises from their n e i g h b o u r s . Of the 4 5

s u b j e c t s who responded, 55.8% were more annoyed while in t h e i r bedrooms whereas 27.8% were more annoyed i n t h e i r living r o o m .

2 . Differences Between Row Housing and Apartment R e s i d e n t s

Of the 98 s u b j e c t s , 16 l i v e d in a p a r t m e n t condominiums and 8 2

l i v e d

In

two-storey

row

h o u s i n g condominiums. Although the number of apartment residents was by d e s i g n very small, some c o m p a r i s o n s between

t h e t w o types of d w e l l i n g s can nevertheless be mde. T a b l e

V

compares

d a t a describing the two groups nF residents. It is seen that the noise

l e v e l s in the homes were qufte similar f o r t h e s e t y p e s of homes. Row

housing was on average s l i g h t l y n o i s i e r i n t h e daytime, perhaps because

of the on average g r e a t e r number of c h i l d r e n in t h e s e homes. There w e r e considerable d i f f e r e n c e s i n t h e

STC

values between t h e two housing

t y p e s , the average STC f o r the apartments measured beFng c o n s i d e r a b l y

less t h a n thar f o r t h e row housing. While these observations certainly cannot be g e n e r a l t z e d , they must be borne I n mind when comparing

annoyance responses, From the other d a t a in Table V, one c a n s e e t h a t

the r o w houstng sample included more expensive homes, more c h i l d r e n , but

no other large differences when compared w i t h the apartment housing sample.

Table V I compares annoyance responses €or the t w o housing t y p e

groups. This table gives percentages of subjects who were "at all annoyed" on each response ( i - e . , scored greater t h a n I ) , and contains

combined d a t a s i m i l a r to those Fn Table TV, A number of results

i n d l c a t e t h a t apartment dwellers

were

much more disturbed rhan row h o u s i n g r e s i d e n t s . F o r example, although the percentage of r e s i d e n t s

annoyed by noises from neighhours on either side of them was o n l y slightly less for t h o s e in apartments than f o r t h o s e in row housing,

t h e y were d i s t i n c t l y mnch more annoyed by: n o i s e s from neighbours above o r b e l w (81.2%), noises i n h a l l s and s t a i r s (68,7%), t r a f f i c noises

(51.2%1, and the sounds of doors slamming. Host of shese examples of

g r e a t e r annoyance f o r apartment d w e l l e r s are n e t r e a d i l y a t t r i b u t e d to

t h e i n f e r i o r average measured STC of their party walls. P e o p l e l i v i n g

i n apartments are s u b j e c t e d to a greater number of sources of a n n o y i n g noises, some af whlch are more likely to be a more s e v e r e p r o b l e m in a p a r t m e n t b u i l d i n g s . Only apartment d w e l l e r s can have neighbours above

or below them, n o i s e s from h a l l s and s t a l t s , and f o o t s t e p noFses above them. 'In a d d i t t o n , because of t h e nature of their b u i l d i n g s , they a r e poteotially exposed to more types of buildlng machinery n o i s e s and d o o r s

slamming. This combination of more sources of annoying n o i s e and g r e a t e r expostire t o some n o i s e sources causes a more s e v e r e noise Impact on them. A case in point is t h e f a c t that a11 f o u r s l e e p

response i t e m s Indicated greater disturbance to a p a r t m e n t dwellers t h a n

generally i n f e r i o r p a r t y - w a l l sound insulation of apartments. A l t l ~ o u g h t h e sound i n s u l a t i o n of floors w a s n o t a c t u a l l y measured i n this s t u d y , it appears to be a more c r i t i c a l problem in apartments t h a n the

i n s u l a t i o n a5 p a r t y w a l l s .

D e s p i t e t h e limitations caused by t h e small number of a p a r t m e n t r e s i d e n t s surveyed, these comparisons c o n f i r m t h e expectat fon t h a t t h e

disturbance by n e i g h b o u r s

'

noises within aparrrnent b u i l d i n g s is a much

more complex p r o b l e m t o untangle than that f o r r w h o u s i n g . They a l s o i n d i c a t e t h e need f o r a d e t a i l e d s t u d y of sound Insulation problems i n floor and cetling assemblies and of f o o t s t e p noise.

3. Cornnosite Resnonse Scales

P r e v i o u s research8 has shown composite response scales to h e more

r e l l a b l e measures of disturbance t h a n single-ftem responses a n d more h i g h l y correlated

with

o b j e c t i v e acoustical measures. I n t h i s s t u d y a

f a c t o r a n a l y s i s was f l r s t carried out a n 2 2 annoyance and s l e e p

disturbance responses, using the principal components method of factor

a n a l y s i s . Any factors w i t h e i g e n v a l u e s greater than l.

Ci

were t h e n rotated by vsrimax. Ffnahly, composite response scales were formed by summing the responses t o i t e m t h a t l o a d e d s t r o n g l y

a n

t h e major factor.

It

was found to be diEficult to c r e a t e a composite r e s p o n s e scale t h a t c o r r e l a t e d much more s t r o n g l y w i t h acoustical measures t h a n d i d the individual i t e m responses. By limiting the p o s s i b l e number OF f a c t o r s

ro t h r e e , and o n l y summing items that had f a c t o r loadtngs 3 0.70 on the

m a j o r f a c t o r , which explained 64% of the response variance, a composfte r e s p o n s e scale was formed. The composite scale i n c l u d e d t h e E o l l o w l n g

ttems: annoyance w i t h n e i g h b o u r s h o i c e s , annoyance w i t h nei~hbours' music sounds, annoyance w i t h noLses from n e i g h b o u r s on either s i d e i n

the daytime, annoyance w i t h n o i s e s from neighbours on e i t h e r side at n i g h t , a n d Frequency of d i f f i c u l t y in f a l l i n g a s l e e p due t o neighbours' noises. This composite annoyance scale, which r ~ s u l k e d from a f a c t o r a n a l y s i s of response scores, is r e f e r r e d t o as r e s p o n s e v a r i a b l e 101 tn

t h i s report.

A second composite annoyance s c a l e was formed by summing t h e € o u r responses c o r r e l a t i n g most h i g h l y wirh measured STC values and is

referred t o as response variable 104. The four items w e r e : perceived

n o i s e i n s u b j e c t ' s own home, annoyance w i t h t h e sounds of n e i g h b o u r s ' voices, annoyance with neighbours' music sounds, and frequency of

d i f f i c u l t y in f a l l P n g a s l e e p due to neighbours' n o i s e s . This somewhat a r b i t r a r i l y dertved s c a l e c o r r e l a t e d more s t r o n g l y w i t h STC v a l u e s t h a n

the s c a l e derived by f a c t o r a n a l y s i s , as will b e s e e n i n t h e f o l l m i n g sections, Although both annoyance scales were used I n subsequent

a n a l y s e s , one s h o u l d be auare of the dffferences in their rnettlod of

formatton.

The Eact that factor analysis fafled to p r o d r ~ c e a composite

response scale with much improved correlations with STC v a l u e s may be

s u b j e c t i v e r e s p o n s e s to traffic n ~ i s e , ~ - ~ T ~ a n d ? subjective ~ ~

responses t o noises caused by n e i g h b o u r s in m l t i - f a m i l y dwellings. Tt

a p p e a r s t h a t traffic n o i s e I s a more homogeneous source of disturbance and many d i f f e r e n t responses related t o a general sense of annoyance t o

t r a f f i c n o i s e , Annoyance w i t h neighbours* n o i s e s d o e s n o t appear to e x h i b i t the same homogeneity. A s discussed in l a t e r sectfons, d i f f e r e n t

t y p e s of noise caused annoyance In different ways. This would explain

why they d l d nnt add together v e r y successfully to form a composite

r e s p o n s e scale. This difference a l s o i n d i c a t e s t h e i m p o r t a n c e of considering each response s e p a r a t e l y t h r o u g h o u t all f u r t h e r a n a l y s e s s i n c e these responses m y r e l a t e q u i t e differently with both a c o u s t i c a l

and nun-aco11s tical predictor v a r i a b l e s .

4 . Physical Variables as Response P r e d i c t o r s

Most of the questionrtatre items designed t o assess the fmpact sf noises from n e i g h b o u r s u s i n g 7-point i n t e r v a l s c a l e responses were form

of dPrect ly e l t c i r e d annoyance. With such q u e s t i o n s t h e r e is a l w a y s t h e

p o s s i b i l i t y t h a t the n a t u r e oE the question is somewhar suggestive and

hence produces a biased, excessively n e g a t i v e response. To v e r i f y t h a t

t h i s was not t h e case, i n i t i a l open-ended q u e s t i o n s were i n c l u d e d to

o b t a i n a measure of s p o n t a n e o u s annoyance to t h e n o i s e o f n e i g h b o u r s . R e s p o n s e variables 009 and 010 l i s t i n g the t h i n g s subjects l i k e d and

d i s l i k e d about t h e i r b u i l d i n g r e s p e c t i v e l y were used to o h t a i n these

s p o n t a n e o u s r e s p o n s e s . The liking of q u i e t n e s s a r the d i s L i k i n g of n o i s e were coded as 2; o t h e r l i k e s or dislikes were coded as 1 and no likes o r dislikes were coded as 0- Cross t a h l a t i o n s were t h e n

performed between t h e s e two response varfables and the STC v a l v e s of the t e s t e d w a l l s w h i c h were grouped into four STC ranges. In b o t h c a s e s a

Chi s q u a r e rest f n d i c a t e d t h a t there was a significant relationship between t h e v a r i a b l e s (p

<

0.02 for varlable 009, a n d p G 0.005 f o r

v a r i a b l e 10). In addition, t h e r e s p o n d e n t s ~ a r i s f a c t - t o n u i t h t h e i r

b u i l d t n g was significantly r e l a t e d to s o m measures of sound i n s u l a t i o n ( T a b l e VII]. T h u s the spontaneous respanses tn questions t h a t d i d n o t m e n t l o n nofse were significantly related r o t h e m e a s u r e d STC of each subject's w a l l .

The r e l a t i o n s h f p s between the

major annoyance responses and t h e

p h y s - l c a l measures of sound i n s u l a t i o n w e r e f i r s t e v a l u a t e d by P e a r s o n

product-moment carrelations be tween p a i r s of v a r i a b l e s . In T a h l e VII

,

whfch g i v e s t h e c a t r e l a t i o n c o e f f i c i e n t s significant a t p G 0.05 l e v e l

or hLghec f o r seven sfngle-nmnber sound insulation measures, it i s seen

t h a t t h e r e a r e a large number of s i g n i f i c a n ~ c o r r e l a t i o n s despite t h e

small sample 198 s u b j e c t s ) . T h l ~ s , t h i s p i l o t survey has s u c c e s s f u l l y

d e m o n s t r a t e d t h a t s Egnif ic a n t r e l a t i o n s h i p s be tween sound i n s u l a t i o n and

annoyance measures can be obtained. 'She correlations between responses

and STC v a l u e s vary f r o m i n s i g n i f i c a n t to a correlation of -0.335.

Correlations with t h e A-weighted transmission loss STA were slightly higher, reaching a maximum a £ -0,378. In a recent: British s t u d y ,

1,angdonl5 found c o r r e l a t i o n s between s u b j e c t i v e r a t i n g s and sound

s u b j e c t s . Thus, the magnitudes o f the c o r r e l a t i o n s shown in TabLe VII

are very much Ln

l i n e

wirh t h e only o t h e r comparable s t u d y . In b o t h t h e

present p i l o t study and Langdon's s t u d y , the Least emotional response c o r r e l a t e d m o s t h i g h l y w i t h the measured sound insulation.

In

t h e

p r e s e n r study this was response variable 0 5 4 , the amount of money

s u b j e c t s were prepared to pay monthly to e l i m i n a t e a n n o y i n g n o i s e s . In

T,angdonls study it was a subjective rating of the existing sound

insulation. Table V I t : i n d i c a t e s t h a t m o s t other annoyance-type

responses correlated wtth STC at about 0.20 o r slightly higher. There

are a l s o a number of q u i t e n o t a b l e excepttons where r e s p o n s e v a r i a b l e s

did not correlate significantly w i t h sound Insulation measures; hence, one m s t assume t h a t the degree of t h e d i s t u r b a n c e is l a r g e l y

independent of t h e sound i n s u l a t i o n of t h e wall. These responses would i n c l u d e : o v e r a l l annoyance w i t h n o i s e s from their neighbours on e i t h e r

side (027), annoyance w i t h speech sounds Ernm their n e i g h b o u r s ' r a d i o o r

r e l e v i s t o n ( 0 3 9 1 , a n n o y a n c e w i t h the sounds of their n e i g h b o u r s '

children ( 0 4

11,

and dayrime annoyance w i t h noises from their n e l g h b o u c s

o n either s i d e ( 0 4 6 ) . In sonre of t h e s e c a s e s , correlations which were marginally significant n i g h t be increased i n a s t u d y w i t h a l a r g e r number of subjecrs.

P r e l i m i n a r y comparisons of the s u i t a b i l i t y of various s o u n d

i n s u l a t i o n measures can be o b t a i n e d Erom Tabla

VTI,

a l t h o u g h i n g e n e r a l t h e r e are o n l y minute d i E fesences between the correlarions with v a r i ~ 11s sound i n s u l a t i o n measures. The differences between DA a n d

DAS

a n d

between DAN and DANS are so small t h a t the differences between a p i n k

source s p e c t r u m and t h e S c h u l t z source spectrum are clearly unimportant in these data. S i n c e STA and DAN

are

physically very similar, it i s n o t s u r p r i s i n g that T a b l e V I I . shms them t o produce v i r t u a l l y i d e n t i c a l correlations w i t h response measures. There does seem to be a t r e n d , h w e v e r , for t h e A-weighted t r a n s m i s s i o n loss measures, such as STA or

DAN, t o produce slightly higher correlations with subjective responses.

The simple A-weighted d i f f e r e n c e i n l e v e l s , DA, produced s l t g h t l y

smaller correlatkons with responses in a l l b u t two c a s e s . For the

q u e s t i o n o n t h e degree of noise p e r c e i v e d by t h e o c c u p a n t i n h i s own home, and the annoyance to sounds of slamming d o o r s , Dh c o r r e l a t e s

slightly mare h f g h l y than do STC or STA. The f i c s t of t h e s e r e s p o n s e s

1s c l e a r l y different in nature from a l l t h e o t h e r s I n that it r a t e s t h e

s u b j e c t ' s own home, The second response (slamming d o o r s ) p r o b a b l y h a s

exaggeraLed c o r r e l a t i o n s . Most s u b j e c t s c o m p l a i n i n g about the n o i s e s of

doors slamming I l v e d i n apartments which tended to have l o w e r STC v a l u e s than t h e other homes. T h u s , the small number of subjects who were

annoyed by d o o r s slamming and who tefided t o live i n a p a r t m e n t s with r e l a t i v e l y low STC v a l u e s could l e a d to somewl~ac misleadingly h i g h

correlations w i t h STC values. A l a r g e r sample o f a p a r t m e n t d w e l l e r s is needed to properly evaluate t h i s response.

Table V I L I gfves correlation coefficients o b t a i n e d between r e s p o n s e

variables and v a r i o u s measures of background n o i s e l e v e l s . Only one response correlated significantly with noise levels measured in the s u b j e c t ' s own h o w ( d e g r e e of n o i s e p e r c e i v e d by o c c u p a n t in his own

home (026). A number a € responses c o r r e l a ~ e d s i g n i r i c a n t l y w i t h t h e d a y t i m e or 24-hour LEO measllred i n t h e neighbour's apartment. mere w a s

a definlte t r e n d s u c h that the r e s p o n s e s n o t correlating significantly

w i t h sound Lnsulation measures d i d c o r r e l a t e s i g n i f i c a n t l y wtth the

n o i s e l e v e l i n the n e i g h b o u r ' s home. These responses i n c l u d e d : general annoyance with n e i g h b o u r s on e i t h e r s i d e (0271, annoyance with n o i s e s of n e i g h b a u r s ' c h i l d r e n (0411, and daytime annoyance with neighbours on e i t h e r side ( 0 4 6 ) . Table VIZI also g i v e s the results of c o r r e l a t i o n s between responses and the difference b e t w e e n the s u b j e c t ' s and t h e neighbour's 24-hour LEQu Although three of the responses d i d correlate s i g n i f i c a n t l y with t h i s n o i s e level difference, t h e s e c o r r e l a t i o n

coefficients nerc always

lower

than t h e

correlations

with t h e netghbour" 24-hour

$

Therefore, t h e r e is no e v i d e n c e t h a t t h e

4

"

d i f f e r e n c e

in

n o i s e l e v e l s between homes is the principal f a c t o r influencing responses. The n o i s e Level difference is j u s t a n o t h e r

v a r i a b l e t h a t is c o r r e l a t e d w i t h t h e neighbour's

hQ2'

( 0 7 4 1 ,

CR

= 0.652, p G 0.001). The p r e s e n t d a t a consequently do n o t s u p p o r t

t h e idea that noLses i n o n e ' s own home can a c t as masking noise and t h u s lead to reduced annoyance w i t h the n o i s e s of nefghhours.

The d a t a do show t h a t different sounds from neighbours cause annoyance hy quite d i f f e r e n t mechanisms. Some noises seem to be

annoying because the sound f n s u l a t i o n of the party wall is not adequate,

while other sounds are annoying q u i t e independent of the properties of

the w a l l , p r o b a b l y s i m p l y because they c r e a t e high sound l e v e l s I n t h e neighbour' s home. The r e l a t i v e l y high correlation between t h e measured

sound tnsulation values of the party walls and the less emotional, more strictly factual responses concerning t h e number o f dollars per month t h e s u b j e c t s a r e prepared to pay to reduce annoying noise, clearly

i n d i c a t e t h a t s u b j e c t s can judge t h e q u a l i t y of t h e sound Cnsulation of

their wall and are concerned enough t o be w f l l i n g to pay to improve it.

However, when the subjects w e r e a s k e d how annoyed they were because of

t h e i r neighbours' n o i s e s , the sound insulation of the wall w a s not t h e o n l y f a c t o r t h a t influenced their answer. S u b j e c t s apparently took the

quality a £ the wall into account and tended to report g r e a t e r annoyanre w i t h excesstvely n o i s y n e i g h b o u s s , as i n d i c a t e d by the significant c o r r e l a t i o n s between annoyance ( 0 2 7 , 0 4 6 3 , and n o i s e l e v e l s in the

n e i g h b o u r s ' homes.

One Eactor that would have reduced the c o r r e l a t i o n b e t w e e n

annoyance responses and measured noise L e v e l s i n t h e n e i g h b o u r s ' homes

was that probably about 50% of the time the most annnylng nelghbour was n o t measured. Each s u b j e c t u s u a l l y had rwo l m r r r e d i a t e nrelghbours, o n e on either side of h i s home. In t h i s s t u d y , measuremerits w e r e only made in one of the neighbouring homes, s a that one c o u l d expect to pi& the more annoying neighbour i n o n l y about 50% of the cases considered- T h f s is a p a r t l c u l a t l y obvtous problem with regard to annoyance due to noises of neighbours' children. Approximately 62% of t h e homes had c h i l d r e n under 18 years o l d . h some cases, reported annoyance due to c h i l d r e n was

c o r r e l a t e d with t h e measured noise l e v e l s in homes w t t h o u t children. In

in a n e i g h b o u r i n g home

with

c h i l d r e n , who were perhaps n o t as n o i s y a s t h e children i n t h e other neighbauring home.

In

spite of this problem, h i g h l y significant c o r r e l a t i o n s were obtained between annoyance due t o

t h e sounds of neighbours' chf l d r e n ( 0 4 1 ) and t h e n e i g h b o u r s ' daytime L

value (072). One can probably conclude that t h e mere p r e s e n c e o f Ert

c h i l d r e n I s sufficient to cause annoyance regardless of t h e l e v e l of

noise they create.

As an initial s t e p in considering the p o s s i b t l i r y of improved single-number measures of sound insulation, t h e principal s u b j e c t i v e

r e s p o n s e s were correlated with the measured sound transmission loss i n

each 1 J 3 octave band. The s t a t i s t t c a l l y significant ( p 4 0 - 0 5 )

cnrrelation coefficients that resulted are presented in T a b l e

TX.

A l l

t h e responses except one (annoyance due to sounds of neighbours'

c h i l d r e n (041)) were significantly related to the 1/3 o c t a v e

rransmisslon loss values in at least one 1/3 ocrave band. However, most

r e s p o n s e s w e t e slgniftcantly r e l a t e d to the TL v a l u e s in o n l y a small

number af bands. F o r most responses, c o r r e l a t i o n w i t h t h e 1 2 5 Hz and 160 Hz 1 / 3 octave band

Tt

values y i e l d e d the M g h e r , if n o t the h i g h e s t , c o r r e l a t i o n coefftcients. tn f a c t , a l l t h e correlation coefficients between responses and rhe 160 Hz

TL

values were h i g h e r than f o r those v l t h STC values. The r e s u l t s gZven i n Table

IX

appear t o I n d i c a t e t h a t rhe lower 1/3 o c t a v e bands a r e most critical i n d e t e r m f n i n g the

r e s u l t i n g disturbance t o residents.

To

better understand the relarionship between t h e p h y s i c a l variables, p r i o r to a t t e m p t i n g to form improved c o m p o s i t e sound

i n s u l a t i o n measures, a l l sound insulation measures were c o r r e l a t e d with one another. The c o r r e l a t i o n coefficients a r e g i v e n in Table X , As was

expecred, many oE these measures were very h i g h l y intercorrelated.

Among the s e v e n single-number o v e r a l l s n u n d insulation v a l u e s (STC, N T C ,

STA, M, DAS,

DAN, DAMS)

intercarrelations were very h f g h , r a n g i n g from

0.9Q4 to 0.9998. These high c o r r e l a t i o n caeEEicients clearly

demonstrated the very high similarity between STA and DAN values. Tl-le

STC and STA v a l u e s were also very similar w i t h a c o r r e l a ~ i n n coefficient of 0.965, The simple A-weighted level difference, DA, differed t h e most

from STC b u t , even s o , c o r r e l a t e d with STC values wtth a coeEEtcient o f

0.904.

It

is therefore not surprising t h a t the r e s u l t s in Table VII

i n d i c a t e no large differences among these v a r l a b l e s a s p r e d i c t o r s of t h e s u h j ectlve r e s p o n s e s .

The c o r r e l a t i o n s between t h e 1/3 o c t a v e sound transmission l a s s

v a l u e s tended t a decrease as the separation of the frequency

I n c r e a s e d . Correlation coefftcients between adjacent 113 o c t a v e bands were g e n e r a l l y apppraxirnately 0.8 to 0.9, b u t f o r bands separated by one I n t e r m e d i a t e band the i n t e r c o r r e l a t i o n s were g e n e r a l l y 0.7 to 0.8. The lowest correlations between lJ3 octave-band TL values w e r e about t h e

same as t h e highest correlations between s u b j e c t f w e responses and sound

insulation measures. T h i s same t a b l e shws rhat t h e STC v a l u e s c o r r e l a t e d m o s t highly with the 113 octave TL values for 1 / 3 octave

IL

w a s hoped t h a t new cornbLnations of 1/3 o c t a v e

TL

v a l u e s could be

found t h a t w a u l d c o t r e l a t e more s t r o n g l y w i t h subjective response measures. Tn an attempt to o b t a i n such new measures, multiple regression analyses were performed regressing each response o n t h e

v a r l o u s

113

o c t a v e

TL

values.

The

order of e n t r y of the 1 / 3 octave TL

p r e d i c t o r s i n t o t h e equation was d e t e r m i n e d a c c o r d i n g to. which one

accounted f a r the largest part o f the unexplained variance a t t h a t step.

No s u c c e s s f u l combfnatinn o f even two 1/3 o c t a v e

TL

v a l u e s was found. That i s , i n no case c o u l d even two 1/3 octave v a l u e s be f o u n d t h a t

when taken together, added s i g n i f i c a n t l y to t h e prediction o f a

s u b j e c t i v e response. This is perhaps n o t s u r p r i s i n g i n v i e w of t h e high

i n t e r c o r r e l a t i o n s b e t w e e n the 113 octave TL v a l u e s g i v e n i n T a b l e X. I n Rrltafn, sound Insulation Ts measured fa term3 of a n A g ~ r e g a t e

Adverse Deviation (AAD) b e l w a reference contour.13 T h l s c o n t o u r is Flat from t h e 1600 Hz t o 3150 Hz 1 / 3 octave b a n d s , w i t h a v a l v e of 56 dR

TL in each 113 o c t a v e band. Relrrw t h i s p l a t e a u t h e contour d r o p s at

4 dB p e r o c t a v e . It was d e s i r e d t o evaluate t h e AAD a s a p r e d i c t o r of s u b j e c t i v e responses. TR addition, t h r e e a t h e r variat tons of the standard AAD were considered in which t h e 4 dB per octave s l o p e was v a r i e d . Slopes of 2, 3 , 4 a n d 5 dl3 p e r o c t a v e were c o n s i d e r e d , The c o r r e l a t i o n s between the resulting

AAD

t y p e measures and t h e

responses are g i v e n in T a b l e

XI.

Varying t h e s l o p e of the r e f e r e n c e

c o n t a u s wlthfn the range j u s t m e n t i o n e d had o n l y v e r y minor e f f e c t s on

t h e resulting c o r r e l a t i o n coefficients. By comparing T a b l e X I with

T a b l e V T I , i t is seen t h a t s l i g h t l y h i g h e r c o r r e l a t i o n s w i t h responses

were o b t a i n e d w i t h AAD v a l u e s a s t h e p r e d i c t o r t h a n w i t h STC values. S i n c e both sound i n s u l a t i o n values and background n o i s e l e v e l s were

found to r e l a t e signiEicankly to responses, it was h o p e d tha't: compound

p r e d i c t o r s could be found that included b o t h t y p e s af p h y s i c a l measures. M u l t l p l e regression a n a l y s e s were perEatmed

in

which t h e o r d e r o f e n t r y

of the predtctor v a r i a b l e s was predetermined to allow easy comparison

b e tween v a r i o u s combinations of p r e d i c t o r s a n d t h e subjective responses. T h r e e sound insulation measures were c o n s i d e r e d in separate a n a l y s e s :

S T C , S T A and AAD. h e of these sound i n s u l a t i o n measures w a s s h e f i r s t

predictor v a r i a b l e e n t e r e d i n t o the equation, followed by the

neighhour's

LE

2 r and f i n a l l y by t h e subject's

$Qzr.

The resulting

'1

m u l t t p l e corre a t i o n coefficients a f t e r each step a r e g i v e n i n T a b l e XII. In a number of cases, as noted earlier, the s i m p l e

c o r r e l a t i o n s between t h e sound i n s u l a t i o n measares and t h e response

v a r i a b l e s were n o t signlffcant, and are i n c l u d e d here only to complete

t h e t a b l e . In many cases t h e second term, t h e neighbour's

hq2*,

d i d

n o t add significantly to the p r e d i c t i o n ,

In

a l l cases, t h e t h i r d term,

t h e s u b j e c r t s own

hnZ4,

d i d n o t add to the prediction of these

s u b j e c t f v e responses. T h a t i s , although in some cases s u c c e s s f u l

c o r n h i n a t i o n s of sound insulation measure and neighbour's L~~~~ were

f o u n d , no successful cambinatLons were found t h a t i n c l u d e d the subject's rnrn T 24. The s i m p l e correlations of T a b l e V Z Z I had i m p l i e d t h a t t h e

%Q

sLmpZe difference between the s u b j e c t ' s and the n e i g h b o u r s t $QZ