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Patterns of behaviour in dwellings exposed to road traffic noise
Journal of Sound and Vibration (1984) 92(2),
159-172
PATTERNS
IN
OF
BEHAVIOUR ROAD J. LAMBERT,
DWELLINGS
TRAFFIC F. SIMONNET
EXPOSED
TO
NOISE AND
M. VALLET
Znstitut de Recherche des Transports, Centre d’Evaluation et de Recherche des Nuisances et de I’Energie, 109 Avenue Salvador Allende, 69500 Bron, France (Received 6 October 1982)
An inquiry involving a total of 1500 subjects residing in 15 different sites in the conurbations of Lyon and Marseilles was carried out in 1979 with a view to determining the behaviour and attitudes of people with regard to traffic noise. The main purpose of the inquiry was to identify the objective reactions to the traffic noise and to determine how such reactions varied with the noise level, with account taken of the socio-economic characteristics of the subjects (age, income, owner occupier or tenant, etc.). The 08.0020.00 hour L, noise level was measured or calculated for each of the dwellings included in the inquiry. The 00.00-05.00 and 20.00-24.00 hour L,, values were also derived for each case and a total of nearly 20 000 different noise levels were involved in the analysis of the data for this inquiry. On considering the completed questionnaires it was found that the annoyance experienced during the day was more closely correlated with the noise level (r = 0.64) than had been the case with the results of previous studies. In addition to showing how traffic noise can interfere with activities and lead, for example, to the closing of windows to shut out the noise, the inquiry yielded information on the way in which activities affected by noise are transferred to quieter rooms, on the extent to which individual dwellings are sound proofed, on the extent to which occupants are likely to move to another dwelling in order to escape from the noise and finally on some aspects of the effects of noise on health and sleep. Thus it appears that a daytime L, value of more than 65 dB(A) gives rise to what can be regarded as forced behaviodral responses to the extent that there are significant changes in the normal way of life of the people concerned and such responses give an indication of the magnitude of the social costs that can be attributed to the undesirable effects of traffic noise.
1. INTRODUCTION Public
authorities
are
responsible
for
deciding
on a level
of noise
that
should
not
be
that the situation for people living in urban areas will be acceptable in the medium term and improved in the long term. Given this requirement it is necessary to assess the effects of noise and in fact this matter has been the subject of numerous inquiries over the last 20 years. The early inquiries conducted by McKennell [l] and Langdon in Great Britain [2], by Borsky in the U.S.A. [3] and by Lamure in France [4] involved very comprehensive studies of certain aspects of human responses to noise. Some of these responses can be verbal and it is possible to arrive at an understanding of what is involved by asking for the opinions of the people concerned. In other cases noise can give rise to behavioural responses whose frequency can be observed. Following this first phase of study, the methodology to be employed was simplified and work tended to be confined to the conduct of inquiries aimed at determining the views of the subjects [5-71. The fact that only slight changes in behaviour had been observed during the course of the early studies had tended to discourage the conduct of inquiries exceeded
in order
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Limited
160
J. LAMRER-I‘,
F
SIMONNET
AND
M.
L’ALLL:I
concerned with behavioural responses. It was also considered that the multiple motives for any behaviour would make it difficult to determine the extent to which noise wa> involved. Furthermore, it appeared that the public authorities were able to make good use of the convergent results of work based on the use of simple scales to express the degrees of annoyance experienced due to noise. Nevertheless, in the case of studies concerned with sites where the situation was very critical [8-lo] some behavioural responses were observed. These observations have rise to a renewed interest in assessments based on observations of changes in conduct and behaviour. The different approach was also justified by the fact that it is difficult to define what is meant by annoyance. Thus the verbal expression of annoyance can depend on a number of psycho-sociological factors associated with the effects of noise in certain circumstances. For example, the owners of dwellings exposed to noise may tend to play down their objection in that the standing of the area would be impaired on admitting that it is noisy or to inflate the degree of annoyance with a view to obtaining some compensation from the public authorities.
2. INQUIRY 2.1.
SCALE
OF THE
INQUIRY
AND
NOISE
PROCEDURE LEVELS
INVOLVED
inquiry was concerned with a total of 1500 subjects, of which 94% were women, and who were either the owners or tenants of flats located in a total of 15 different sites. The dwellings were fronted by urban express ways or main through roads in the case of the noisy sites or by service roads in the case of the quieter suburban locations. The subjects were equally distributed between Lyon and Marseilles. As shown in Figure 1, the inquiry was concerned with a fairly wide range (30 dB(A)) of noise levels. It will also be noted that one-third of the sample of subjects were concerned with noise levels of less than 60 dB(A), one-third with noise levels of 60-68 dB(A) and one-third with noise levels of more than 68 dB(A). The
47
54
dB(A)
L,,
Figure
2.2.
EVALUATION
60
66
72
76
36
08.00-20.00
hours
1. Histograms
of interviewed
OF THE
NOISE
42
de(A)
people
!-Q&In 46
q
54
00.00-05.00
versus
60
66
hours
noise level.
LEVELS
noise levels were determined on the basis of different complementary procedures: measurement of the noise over 24 hour periods at one or two points at each site; measurement of the noise over short periods of time at a number of points at each site; calculation of the noise levels at the facade of each dwelling, involving adjusting the results of the noise measurements and making use of the NOISE computer programme developed by IRT-CERNE [ 111. Thus an 08.00-20.00 hour L, value applying to the facade of each room of each (20.00-24.00 hours) and dwelling was determined. The L, values for the evening The
BEHAVIOUR
PATTERNS
DUE
TO
TRAFFIC
NOISE
161
night-time (00.00-05.00 hours) periods were derived from the daytime values by taking account of the results of the single point, long duration measurements of noise at each site. 2.3. ITEMS CONSIDERED IN THE QUESTIONNAIRE Following in-depth interviews and a pilot inquiry involving a total of 300 subjects it was assumed that the behaviour and attitudes of people could best be observed with respect to the following aspects of daily life within the home: the way in which people make use of and organize the available accommodation; the health of the subjects and in particular the taking of medicaments; the way in which the subjects spend their time, the interest here being in the way noise can affect the duration and distribution of day-to-day activities (for example, the extent to which subjects leave their dwelling in order to escape from the noise); the expenditure either within the dwelling or on the building itself (upkeep of the rooms, sound proofing of the facades). Thus the questionnaire was made up of a total of 113 questions that were distributed with regard to the different matters of interest as follows: 20 questions concerning the individual characteristics of the subject; 10 questions on the characteristic features of the dwelling with a drawing presented on the reverse side of each questionnaire for use in giving indications of the noise levels applying to the facade of each room; six questions concerning the degree of annoyance due to noise; 24 questions concerned with the effects of the noise on health and sleep; 53 questions concerning behaviour related to the use of the dwelling, on the contents and on the distribution of different activities with respect to time. Given the fairly satisfactory understanding of the relationship between noise and the degree of annoyance as a result of previous inquiries, it was concluded that it would be profitable to study the relationship between noise and its effects on behaviour. 2.4. ANALYSIS OF THE DATA The data concerning the exposure to noise and the replies given on the questionnaires were processed and analyzed at IRT-CERNE. Apart from “conventional” analytical treatment concerned with a correlation of the data and the application of simple x2 tests, more sophisticated analyses were also carried out, based on the use of procedures such as principal components analysis (PCA), variance analysis and consideration of the results on the basis of various subsidiary classifications of the data. This last procedure in particular enabled a determination to be made of the noise levels above which there were significant increases in the incidence of the different behavioural responses that were considered.
3. RESULTS
3.1. ANNOYANCE DUE TO THE NOISE Although the inquiry was concerned in particular with the effects of noise on behaviour it was considered that the degree of annoyance expressed as a result of the noise should be evaluated in order to be able to compare the two kinds of results. The degrees of annoyance were recorded with respect to a 4-point scale for the noise arising both during the day and the night. 3.1.1. Annoyance due to daytime noise The noise index employed here was the 08.00-20.00 hour L, value which has been recognized by IRT-CERNE since 1974 as an index that has a good correlation with the degree of annoyance that is expressed [6]. Figure 2 shows how the degree of annoyance
162
J. I.AMREKT.
F. SIMONNET
AND
dB(Al Leq 08.00-20.00 Figure 2. Day annoyance and noise. ---, little annoyed; -A--. people not annoyed.
People
very annoyed;
M.
VALLEI
hours ---,
people
annoyed;
--O--,
people a
expressed as a result of noise arising during the day varies with the level of that noise. More revealing is the way in which the parameter “Percentage of people rather or very annoyed” varies with the noise level as shown by Figure 3. This shows clearly that there are two critical levels of noise, one in the region of 60 dB(A) and the other in the region of 65 dB(A), above which there are more rapid increases in the degree of annoyance with increasing amounts of noise. The same result is obtained by considering the results with respect to various subsidiary classifications.
/’
/---( ,I 50
55
60
65
dB(A) Le4 00.00-20.00 Figure
3. Day annoyance
70
75
hours
and noise. People very annoyed
plus annoyed.
The results also show that there is a good correlation between the noise level and the degree of annoyance as indicated in Table 1. Thus more than 40% of the variance in the degree of annoyance can be considered to be due to the variance in the noise level. 3.1.2.
Annoyance
due to noise at night
The appropriate noise index at night was considered to be the 00.00-05.00 hour L, value. Figure 4 shows how the degree of annoyance varied as a function of the night-time noise level. This time it is not so easy to identify the level above which there is a more rapid increase in the degree of annoyance as the amount of noise increases, as was the case for the noise occurring during the day, although it does appear that the percentage of people who say that they were very annoyed tends to increase more rapidly above a noise level of 52 dB(A).
BEHAVIOUR
PATTERNS
DUE
TABLE
TO TRAFFIC
163
NOISE
1
Correlation between day annoyance and noise
Annoyance Individual reply Median reply
Index
Numbers of observations. N
L,,8 h-20 h L,,8 h-20 h
1486 30
dB(A)
Figure 4. Night annoyance and noise. --. little annoyed; --A--, people not annoyed.
L,,
00.00-05.00
Correlation coefficient, r 0.64 0.96
Probability, P ~0.01 ~.O.Ol
hours
People very annoyed;
---,
people annoyed:
-O---.
people
a
The correlation between the night-time noise and the annoyance, although not so good as for the daytime case, is still very significant as is indicated in Table 2. These noiseannoyance correlations are appreciably greater than was the case for previous inquiries, particularly those conducted by Vallet [6] and Aubree [ 121 in France, where the correlation was no better than 0.32 and more recently by Myncke and Cops in Belgium [13] and Bradley and Jonah in Canada [14] where the correlation was only a little above 0.40. TABLE
2
Correlation between night annoyance and noise
-.
Annoyance
Individual reply Median reply
3.2. 3.2.1.
BEHAVIOUR
Numbers of observations, N
Index
L,,0 h-5 h L,,0 h-5 h IN RESPONSE
TO THE
Correlation coefficient, r
1486
0.48
30
0.95
Probability,
P __~___
NOISE
Way in which the subject makes use of his dwelling
The two forms of behaviour to shut out the noise and the as a result of noise, to quieter It was found that windows television, when reading and noise where there tended to
considered under this heading were the closing of windows transfer of activities, that could have been interfered with rooms. tended to be closed more particularly when watching before going to sleep (see Figure 5). The critical level of be a more rapid increase in the window closing response,
164
F. SIMONNET
J. LAMBEKT.
48
51
54
de(A)
Figure lecture.
5. Percentage
of people
closing
57
60
L,,
their windows
63
AND
66
08.00-20.00
for:
69
M. VALLET
72
75
78
hours
?? , watching TV; 0, conversation;
?? , ? sleep; A,
as the noise increased, amounted to about 62 dB(A) for the daytime activities and about 52 dB(A) on going to sleep. A significant difference in behaviour was observed with regard to the sites in Lyon and Marseilles, respectively. Thus windows were not closed to the same extent in Marseilles, at least for noise levels up to about 72 dB(A), presumably because of the milder climate. Above this critical noise level it appears that all subjects felt compelled to close their windows such that the climate no longer had any effect. As regards the transfer of activities susceptible to the effects of noise to quieter rooms, it ,was found that the critical noise level above which there was a significant response during the daytime period amounted to L, 3 68 dB(A). The activities mainly involved here were reading and work of an intellectual nature carried out in the home, these being activities that can often be transferred from one room to another without too much difficulty. On the other hand there was no significant transfer of activity so far as watching the television or sleeping was concerned. Clearly there are difficulties with regard to the transfer of these last two activities, either because of the lack of a spare room or because of the physical difficulties involved in moving an item of equipment such as a television set to another room. The effect of the noise on the use of balconies was determined by considering a number of relevant activities that are more or less affected by noise. Of these activities the only ones that are really affected by noise, and then only moderately, are those listed in Figure 6. In fact it was found that the subjects only indulged in these activities to a limited extent even when the noise levels in the vicinity of the balconies was very low (L, < 50 dB(A)). Thus only 23% of the subjects held any conversations on their balconies in spite of the low levels of noise that applied. It therefore seems likely that the use of balconies depends very largely on other factors such as the presence of sunshine, the size of the balcony and the degree of seclusion that is offered, and that the noise level is only of secondary importance. 3.2.2. Effect of noise on sleep and health The effect of noise on sleep has been the subject of a number of studies, particularly with regard to the physiological effects [ 151. This study however was more concerned with the identification of simple indicative parameters and the determination of critical noise levels. The indicative parameters were concerned with the conditions that can apply on going to sleep: time taken in getting to sleep, difficulties in getting to sleep, taking of
BEHAVIOUR
Figure
6. Percentage
PATTERNS
of balconies
DUE
TO
used for: ----,
TRAFFIC
flowers;
-,
165
NOISE
conversation:
- - -. lunch.
sleeping tablets and the extent to which noise results in the subjects waking up during the night. Table 3 gives the degree of correlation with the noise, the level of significance and the two noise levels above which there are significant increases in the effects, for each of the indicative parameters. These results as well as those obtained on carrying out a principal components analysis lead one to the following conclusions: noise appears to have a much more pronounced effect in waking people up than in preventing them from getting to sleep, this latter difficulty being more closely related to the age of the subjects; the interference with sleep leads to an appreciable increase in the taking of sleeping tablets although there appears TABLE
3
Some relationships between sleep and noise levels outside bedroom walls Night-time noise thresholds (during the day)
Correlations with Indicator
_~____ Percentage of people falling asleep within less than 20 min Difficulties in getting MO years
the
noise level __.__~ 0.65
Level of significance 1%
First threshold
Second threshold ss (65)
to sleep: 0.04 0.17
Not significant 1%
Percentage of people often and very often having difficulty in getting to sleep
0.73
< 1%
55 (65)
Percentage of people taking sleeping tablets on going to bed
0.76
< 1%
55 (65)
0.09 0.22
Not significant < 1%
0.86
< 1%
Being woken >50 years <50 years
up during
the night:
Percentage of people often and very often woken up during the night
55 (63)
166
J. LAMBERT,
F. SIMONNET
AND
M. VAL.L.ET
to be a stronger connection with age here than with the presence of noise ( 13% of people taking sleeping tablets for noise levels of SO dB(A) and 20% when the noise level amounts to 75 dB(A)). Although there is only a slight correlation between the noise and some of the indicative parameters it should be noted that the critical noise levels. above which there are more rapid increases in the interference with sleep, are the same for all of these parameters. Thus, to consider just two critical levels, there are rapid increases in the effects for all of these parameters above L, values of 45 and 55 dB(A) for the 00.00-05.00 hour period which correspond to L, values of 55 and 6.5 dB(A) for the 08.00-20.00 hour period. As to medicament consumption, not only on going to bed but also during the day, then, as shown in Figure 7, it was found that there are rather significant relations with the level of noise. If some subsidiary classifications of the subjects with regard to the 20 r-
5 I
O/d 50
55 dE(A)
Figure
L,,
7. Medicament
00.00-20.00
consumption
hours
versus noise
taking of sleeping tablets are considered it can be seen how this practice is related to sleeping difficulties. Thus subjects who have difficulties in getting to sleep are much more likely to take sleeping tablets: 33% compared with 10% in general and 57% when the subjects are more than 65 years of age. In this latter case, the presence of noise simply reinforces the behaviour, the percentage of subjects taking taking sleeping tablets rising to 69% for noise levels of L, z=65 dB(A). On the other hand, subjects that tend to get to sleep fairly quickly seldom take sleeping tablets, particularly if they are young (less than 5%). 3.2.3.
Items used in the home and expenditure on the dwelling itself
The results did not reveal any significant variations in the possession of items whose use can be affected by noise such as record players, radios, television sets and hi-fi assemblies, or in the average times spent in listening to such devices, which tend to remain the same whatever the noise level. As regards expenditure on the home or building itself it was necessary to make a distinction between the normal expenditure associated with the furnishing and upkeep of the different rooms and the comparatively large outlay involved in the fitting of sound proofing materials to the external faces of the rooms. Whereas the expenditure on the furnishing and upkeep of the different rooms did not appear to be affected by the level of noise, this was not the case with regard to expenditure on sound proofing where the noise level played a major role. Figure 8 shows clearly how the percentage of dwellings that have been sound proofed increases with the noise level.
BEHAVIOUR
PATTERNS
DUE
TO
TRAFFIC
NOISE
167
30 aJ $ 5 2 a”
zo-
IO-
0’.
50
’
55 dB(A)
Figure 8. Percentage
of sound proofed
60 L.,
65 08.00-20.00
dwellings versus noise. p,
70
75
hours Owners:
‘, tenants; - - -. total sample.
A number of different factors are involved here and if one considers the results concerning the sound proofing of the dwellings with respect to different criteria (see Figure 9) it will be seen that the following conclusions can be drawn. Noise level is the most important factor involved and the proportion of dwellings that have been sound proofed becomes significantly greater as the noise level rises above 66-68 dB(A) (24 in place of 8%). Income is only involved for noise levels of less than 66-68 dB(A). Thus it would seem that the lower levels of noise and the consequent effects are not regarded as being sufficiently objectionable for people to accept the considerable expenditure involved in sound proofing except for households where there is a high income (> 7000 French francs per month). For noise levels above 66-68 dB(A), however, the objectionable effects seem to be sufficiently great that people tend to regard sound proofing as a facility that needs to be provided regardless of cost. Owner-occupier or tenant: owner-occupiers have a different attitude than do the tenants here. Thus the former consider that expenditure on the provision of sound proofing is an investment which can increase the value of their property (see Figure 8). Length of occupation: people who have occupied their dwelling for a long time tend to be more ready to spend money on sound proofing than do people who have only recently taken up residence. This would seem to be in direct support of the claim that people do not get used to noise. 3.2.4.
Escaping from the home
The last type of behaviour where it was assumed that noise could be involved was that of escaping from the home. More precisely, the question to be answered was whether or not a high level of noise could result in an individual and his family leaving their premises. either for limited periods of time, that is, during the course of the day in the case of housewives or over the week-end in the case of the whole family (e.g., on visiting friends). or permanently, that is, moving to another dwelling. The results indicated that whereas the noise did not give rise to families going out any more, either during the week or at weekends (which would have been a useful indication of attempts to escape from the noise), it did lead to some families considering the possibility of moving. However, although the noise was involved to some extent here it did not appear to be the main reason for moving. The analysis of this type of response was delicate, namely the intention to move to another dwelling, but one can nevertheless draw the following conclusions.
168
_I. LAMBERT.
F. SIMONNET
AND
M. VALLE7
BEHAVIOUR
PATTERNS
DUE
TO
TRAFFIC
NOISE
169
The status of occupation of the dwelling has a dominant effect. Thus not only is it easier for a tenant, as opposed to an owner of a property, to move (no difficulties with regard to the selling of the property) but there may be other obvious reasons for moving apart from the question of noise (need to find more suitable accommodation, desire to purchase a house, etc.). On the other hand the amount of a low rent to be paid and the difficulty of finding equivalent accommodation can discourage a tenant from moving. Finally, there is an effect of noise which becomes more pronounced for levels above 66-68 dB(A) and when it is found that a low rent is not enough to prevent tenants from moving. Thus it would appear that there cannot be any monetary compensation for the higher noise levels. It should also be noted that the fact that he has sound proofed his dwelling is likely to discourage an occupant from moving. Thus the two behavioural responses of sound proofing the dwelling or moving, which are both more likely to arise for noise levels of more than 66-68 dB(A), can be regarded as alternative possibilities. 4. DISCUSSION The correlation between the noise level and the annoyance appears to be much greater than was the case for previous inquiries. There would appear to be three reasons for this higher correlation. First of all it is probable that the greater accuracy involved in the measurement of the noise and the determination of the L, values that were applicable in each case accounted for the much stronger relation. Seconaly, the fact that the sample was made up to a large extent of women confined to the home would have reinforced the correlation; thus Vallet in 1974 [6] established that there was a significant difference in the noise-annoyance correlation for the “inactive” subjects considered in isolation (r = O-47) than for the complete sample of subjects (r = 0.31). Finally, it is likely that one is beginning to witness the results of a greater awareness of noise on the part of the public; thus it should be noted that the correlation obtained in the case of recent inquiries, and more particularly in the case of that conducted by Bradley, appears to be significantly greater than that obtained as a result of inquiries that were conducted some 10 years ago. The possibility of transferring activities to quieter rooms is dependent on the following three conditions: the presence of two constrasting levels of noise within the dwelling; the size of the dwelling and the number of people in the family: for example, it is not possible to make use of a quieter room for sleeping if a room cannot be made available for this purpose; the nature of the activity to be transferred: one can make a comparison here between individual activities, such as reading or intellectual activities, that are undertaken at home and which can be readily transferred and family activities, such as watching the television and collective leisure activities. which cannot be undertaken in just any room of the dwelling. It would seem that the climate can have significant effects on the behaviour in response to noise. Thus it was found that there was a greater reluctance to close the windows to shut out the noise and to spend money on sound proofing in Marseilles than was the case for the subjects living in Lyon and this probably accounts for the generally greater degree of annoyance expressed by the subjects living in the former location (given that the internal noise levels would have been higher in the Marseilles dwellings). As has been seen, behavioural responses depend to a large extent on variables other than noise. Thus the responses can depend on individual characteristics, namely the age and family situation of the subject and on whether the subject is an owner-occupier or
170
J. LAMBEK7‘. F. SIMONNt-I‘ AND
M. VALLtI
tenant, or on what amounts to constraints which limit the action that can be taken in the presence of noise such as the amount of income and the size of the dwelling. Some responses can be direct reactions to the annoyance that is being experienced, such as the closing of windows to shut out the noise, while others can be directed at minimizing the effects, such as the sound proofing of the dwellings. Depending on the particular situation the responses can be closely related to one another (tendency to leave the premises at the weekends or plans to move to another dwelling in order to escape from the noise) or they can amount to alternative possibilities (moving to another dwelling or sound proofing of the existing accommodation). It should be appreciated that the analysis of all these possible responses is no easy matter and the subject therefore deserves to be considered in much more detail in the future, given its complexity and the difficulties in understanding what is involved.
5. CONCLUSION In this study it was attempted to assess the effects of traffic noise by considering the adaptive or evasive behavioural responses to such noise. The different indicative parameters that were considered are listed in Table 4 together with an indication of the critical levels above which the noise appears to have significant effects in each case.
TABLE Indicative
parameters
4
relative to road trafic
noise impact threshold
L,, (A) 08.00-20.00
I
60-62 dB(A)
7
50-52 dB(A) Percentage
of very and
h
66-68 dB(A)
63-65 dB( A)
L,, (A) 00.00-05.00
noise levels
69-70 dB( A)
h
53-55 dB(A) Annoyance
rather annoyed people: day period night period Expressed noisiness Effects on sleep and health People having difficulty getting to sleep People waking in the night People getting rapidly to sleep Leg troubles Digestion difficulties
Headaches
Sleeping tablets consumption Closing windows watching TV lecture sleep
for
Behaviour Transfer of activities to quieter rooms Moving to another dwelling Sound proofing the dwelling
Medicaments for heart troubles consumption
BEHAVIOUR
PAlTERNS
DUE
TO
TRAFFIC
NOISE
171
As a result of the study it is possible to come to the following conclusions. 1. Below 55 dB(A) for the daytime value of J!,,, it can be assumed that the noise gives rise to little or no disturbance and that the level of noise is such that activities that are most likely to be affected by noise can be carried out quite normally. 2. Between 55 and 60dB(A) the effects of the noise are still acceptable but people who are most sensitive to noise are beginning to be disturbed. 3. Between 60 and 65 dB(A) one begins to see some behavioural responses that are not as yet very forced (e.g., the closing of windows to shut out the noise). However, the effects with regard to sleeping and the degree of annoyance that is experienced increase very significantly. It is desirable that action be taken to reduce the noise level but the results of a cost-benefit analysis of such action will not necessarily be very positive, at least in the case of palliative measures such as the provision of sound barriers or the application of sound proofing treatment. 4. Above 65 dB(A) one begins to see compulsive behavioural responses which are indicative of severe disturbance due to the noise (transfer of activities to quieter rooms, sound proofing of dwellings, moving to other accommodation). Action by the public authorities in this case is not only desirable but essential particularly since in most cases the net economic benefit of any action has every chance of being positive for the community as a whole. Although these propositions are more restrictive than is the case for the current French recommendations (L, = 65 f 5 dB(A)) they are on the other hand in complete agreement with the recommendations of the Swiss Federal Office for the Protection of the Environment [16] and those put forward by the Environmental Protection Agency (EPA) of the U.S.A. ACKNOWLEDGMENTS This study was carried out at the request of the Centre d’Etude des Transports Urbains (Urban Transport Studies Centre) and IRT-CERNE express their thanks to this organization for their permission to publish the results of the work. Thanks are also due to Dr F. J. Langdon for his invaluable advice during the preparation of this paper. REFERENCES 1. A. C. MCKENNELL 1963 Aircraft Noise Annoyance around London (Heathrow) Airport SS, 337. London: Her Majesty’s Stationery Office. 2. F. J. LANGDON and I. D. GRIFFITHS 1968 JournalofSound and Vibration 8,16-32. Subjective responses to road traffic noise. 3. P. N. BORSKY 1961 WADD Technical Report, 60-689, AF 33 and 41. Community reactions to Air Force noise, I and II. 4. C. LAMURE and M. BACELON 1967 Cahiers du C.S.T.B no 88. La gke due au bruit de la
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AND
M. VALLE'I
10. B. VOISIN 1977 ARPENTReporr. PrCCtude clinique des comportements dans I‘habitat soumts au bruit de circulation. 11. B. FAVRE 1975 IRT Report. MCthode de calcul automatique des niveaux de bruit de la
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of Sound and Vibration 66, 589-604. The effects of site selected variables on human responses to traffic noise, Part I: Type of housing by traffic noise level.
15. B. GRIEFAHN, G. JANSEN and W. KLOSTERK~TTER 1976 UmweltbundesamtBerlin,
Berichte von Schlaf Literatur. DE L’ENVIRONNEMENT SUISSE 1979 Premier 16. OFFICE FEDERAL POUR LA PROTECTION Rapport Purtiel. Valeurs limites pour I’exposition au bruit du trafic routier. 4/76. Zur Problematik
larmbedingter
Schlafstorungen;
eine Auswertung
159-172
PATTERNS
IN
OF
BEHAVIOUR ROAD J. LAMBERT,
DWELLINGS
TRAFFIC F. SIMONNET
EXPOSED
TO
NOISE AND
M. VALLET
Znstitut de Recherche des Transports, Centre d’Evaluation et de Recherche des Nuisances et de I’Energie, 109 Avenue Salvador Allende, 69500 Bron, France (Received 6 October 1982)
An inquiry involving a total of 1500 subjects residing in 15 different sites in the conurbations of Lyon and Marseilles was carried out in 1979 with a view to determining the behaviour and attitudes of people with regard to traffic noise. The main purpose of the inquiry was to identify the objective reactions to the traffic noise and to determine how such reactions varied with the noise level, with account taken of the socio-economic characteristics of the subjects (age, income, owner occupier or tenant, etc.). The 08.0020.00 hour L, noise level was measured or calculated for each of the dwellings included in the inquiry. The 00.00-05.00 and 20.00-24.00 hour L,, values were also derived for each case and a total of nearly 20 000 different noise levels were involved in the analysis of the data for this inquiry. On considering the completed questionnaires it was found that the annoyance experienced during the day was more closely correlated with the noise level (r = 0.64) than had been the case with the results of previous studies. In addition to showing how traffic noise can interfere with activities and lead, for example, to the closing of windows to shut out the noise, the inquiry yielded information on the way in which activities affected by noise are transferred to quieter rooms, on the extent to which individual dwellings are sound proofed, on the extent to which occupants are likely to move to another dwelling in order to escape from the noise and finally on some aspects of the effects of noise on health and sleep. Thus it appears that a daytime L, value of more than 65 dB(A) gives rise to what can be regarded as forced behaviodral responses to the extent that there are significant changes in the normal way of life of the people concerned and such responses give an indication of the magnitude of the social costs that can be attributed to the undesirable effects of traffic noise.
1. INTRODUCTION Public
authorities
are
responsible
for
deciding
on a level
of noise
that
should
not
be
that the situation for people living in urban areas will be acceptable in the medium term and improved in the long term. Given this requirement it is necessary to assess the effects of noise and in fact this matter has been the subject of numerous inquiries over the last 20 years. The early inquiries conducted by McKennell [l] and Langdon in Great Britain [2], by Borsky in the U.S.A. [3] and by Lamure in France [4] involved very comprehensive studies of certain aspects of human responses to noise. Some of these responses can be verbal and it is possible to arrive at an understanding of what is involved by asking for the opinions of the people concerned. In other cases noise can give rise to behavioural responses whose frequency can be observed. Following this first phase of study, the methodology to be employed was simplified and work tended to be confined to the conduct of inquiries aimed at determining the views of the subjects [5-71. The fact that only slight changes in behaviour had been observed during the course of the early studies had tended to discourage the conduct of inquiries exceeded
in order
159 0022460X/84/020159+14$03.00/0
01984 AcademicPressInc.(London)
Limited
160
J. LAMRER-I‘,
F
SIMONNET
AND
M.
L’ALLL:I
concerned with behavioural responses. It was also considered that the multiple motives for any behaviour would make it difficult to determine the extent to which noise wa> involved. Furthermore, it appeared that the public authorities were able to make good use of the convergent results of work based on the use of simple scales to express the degrees of annoyance experienced due to noise. Nevertheless, in the case of studies concerned with sites where the situation was very critical [8-lo] some behavioural responses were observed. These observations have rise to a renewed interest in assessments based on observations of changes in conduct and behaviour. The different approach was also justified by the fact that it is difficult to define what is meant by annoyance. Thus the verbal expression of annoyance can depend on a number of psycho-sociological factors associated with the effects of noise in certain circumstances. For example, the owners of dwellings exposed to noise may tend to play down their objection in that the standing of the area would be impaired on admitting that it is noisy or to inflate the degree of annoyance with a view to obtaining some compensation from the public authorities.
2. INQUIRY 2.1.
SCALE
OF THE
INQUIRY
AND
NOISE
PROCEDURE LEVELS
INVOLVED
inquiry was concerned with a total of 1500 subjects, of which 94% were women, and who were either the owners or tenants of flats located in a total of 15 different sites. The dwellings were fronted by urban express ways or main through roads in the case of the noisy sites or by service roads in the case of the quieter suburban locations. The subjects were equally distributed between Lyon and Marseilles. As shown in Figure 1, the inquiry was concerned with a fairly wide range (30 dB(A)) of noise levels. It will also be noted that one-third of the sample of subjects were concerned with noise levels of less than 60 dB(A), one-third with noise levels of 60-68 dB(A) and one-third with noise levels of more than 68 dB(A). The
47
54
dB(A)
L,,
Figure
2.2.
EVALUATION
60
66
72
76
36
08.00-20.00
hours
1. Histograms
of interviewed
OF THE
NOISE
42
de(A)
people
!-Q&In 46
q
54
00.00-05.00
versus
60
66
hours
noise level.
LEVELS
noise levels were determined on the basis of different complementary procedures: measurement of the noise over 24 hour periods at one or two points at each site; measurement of the noise over short periods of time at a number of points at each site; calculation of the noise levels at the facade of each dwelling, involving adjusting the results of the noise measurements and making use of the NOISE computer programme developed by IRT-CERNE [ 111. Thus an 08.00-20.00 hour L, value applying to the facade of each room of each (20.00-24.00 hours) and dwelling was determined. The L, values for the evening The
BEHAVIOUR
PATTERNS
DUE
TO
TRAFFIC
NOISE
161
night-time (00.00-05.00 hours) periods were derived from the daytime values by taking account of the results of the single point, long duration measurements of noise at each site. 2.3. ITEMS CONSIDERED IN THE QUESTIONNAIRE Following in-depth interviews and a pilot inquiry involving a total of 300 subjects it was assumed that the behaviour and attitudes of people could best be observed with respect to the following aspects of daily life within the home: the way in which people make use of and organize the available accommodation; the health of the subjects and in particular the taking of medicaments; the way in which the subjects spend their time, the interest here being in the way noise can affect the duration and distribution of day-to-day activities (for example, the extent to which subjects leave their dwelling in order to escape from the noise); the expenditure either within the dwelling or on the building itself (upkeep of the rooms, sound proofing of the facades). Thus the questionnaire was made up of a total of 113 questions that were distributed with regard to the different matters of interest as follows: 20 questions concerning the individual characteristics of the subject; 10 questions on the characteristic features of the dwelling with a drawing presented on the reverse side of each questionnaire for use in giving indications of the noise levels applying to the facade of each room; six questions concerning the degree of annoyance due to noise; 24 questions concerned with the effects of the noise on health and sleep; 53 questions concerning behaviour related to the use of the dwelling, on the contents and on the distribution of different activities with respect to time. Given the fairly satisfactory understanding of the relationship between noise and the degree of annoyance as a result of previous inquiries, it was concluded that it would be profitable to study the relationship between noise and its effects on behaviour. 2.4. ANALYSIS OF THE DATA The data concerning the exposure to noise and the replies given on the questionnaires were processed and analyzed at IRT-CERNE. Apart from “conventional” analytical treatment concerned with a correlation of the data and the application of simple x2 tests, more sophisticated analyses were also carried out, based on the use of procedures such as principal components analysis (PCA), variance analysis and consideration of the results on the basis of various subsidiary classifications of the data. This last procedure in particular enabled a determination to be made of the noise levels above which there were significant increases in the incidence of the different behavioural responses that were considered.
3. RESULTS
3.1. ANNOYANCE DUE TO THE NOISE Although the inquiry was concerned in particular with the effects of noise on behaviour it was considered that the degree of annoyance expressed as a result of the noise should be evaluated in order to be able to compare the two kinds of results. The degrees of annoyance were recorded with respect to a 4-point scale for the noise arising both during the day and the night. 3.1.1. Annoyance due to daytime noise The noise index employed here was the 08.00-20.00 hour L, value which has been recognized by IRT-CERNE since 1974 as an index that has a good correlation with the degree of annoyance that is expressed [6]. Figure 2 shows how the degree of annoyance
162
J. I.AMREKT.
F. SIMONNET
AND
dB(Al Leq 08.00-20.00 Figure 2. Day annoyance and noise. ---, little annoyed; -A--. people not annoyed.
People
very annoyed;
M.
VALLEI
hours ---,
people
annoyed;
--O--,
people a
expressed as a result of noise arising during the day varies with the level of that noise. More revealing is the way in which the parameter “Percentage of people rather or very annoyed” varies with the noise level as shown by Figure 3. This shows clearly that there are two critical levels of noise, one in the region of 60 dB(A) and the other in the region of 65 dB(A), above which there are more rapid increases in the degree of annoyance with increasing amounts of noise. The same result is obtained by considering the results with respect to various subsidiary classifications.
/’
/---( ,I 50
55
60
65
dB(A) Le4 00.00-20.00 Figure
3. Day annoyance
70
75
hours
and noise. People very annoyed
plus annoyed.
The results also show that there is a good correlation between the noise level and the degree of annoyance as indicated in Table 1. Thus more than 40% of the variance in the degree of annoyance can be considered to be due to the variance in the noise level. 3.1.2.
Annoyance
due to noise at night
The appropriate noise index at night was considered to be the 00.00-05.00 hour L, value. Figure 4 shows how the degree of annoyance varied as a function of the night-time noise level. This time it is not so easy to identify the level above which there is a more rapid increase in the degree of annoyance as the amount of noise increases, as was the case for the noise occurring during the day, although it does appear that the percentage of people who say that they were very annoyed tends to increase more rapidly above a noise level of 52 dB(A).
BEHAVIOUR
PATTERNS
DUE
TABLE
TO TRAFFIC
163
NOISE
1
Correlation between day annoyance and noise
Annoyance Individual reply Median reply
Index
Numbers of observations. N
L,,8 h-20 h L,,8 h-20 h
1486 30
dB(A)
Figure 4. Night annoyance and noise. --. little annoyed; --A--, people not annoyed.
L,,
00.00-05.00
Correlation coefficient, r 0.64 0.96
Probability, P ~0.01 ~.O.Ol
hours
People very annoyed;
---,
people annoyed:
-O---.
people
a
The correlation between the night-time noise and the annoyance, although not so good as for the daytime case, is still very significant as is indicated in Table 2. These noiseannoyance correlations are appreciably greater than was the case for previous inquiries, particularly those conducted by Vallet [6] and Aubree [ 121 in France, where the correlation was no better than 0.32 and more recently by Myncke and Cops in Belgium [13] and Bradley and Jonah in Canada [14] where the correlation was only a little above 0.40. TABLE
2
Correlation between night annoyance and noise
-.
Annoyance
Individual reply Median reply
3.2. 3.2.1.
BEHAVIOUR
Numbers of observations, N
Index
L,,0 h-5 h L,,0 h-5 h IN RESPONSE
TO THE
Correlation coefficient, r
1486
0.48
30
0.95
Probability,
P __~___
NOISE
Way in which the subject makes use of his dwelling
The two forms of behaviour to shut out the noise and the as a result of noise, to quieter It was found that windows television, when reading and noise where there tended to
considered under this heading were the closing of windows transfer of activities, that could have been interfered with rooms. tended to be closed more particularly when watching before going to sleep (see Figure 5). The critical level of be a more rapid increase in the window closing response,
164
F. SIMONNET
J. LAMBEKT.
48
51
54
de(A)
Figure lecture.
5. Percentage
of people
closing
57
60
L,,
their windows
63
AND
66
08.00-20.00
for:
69
M. VALLET
72
75
78
hours
?? , watching TV; 0, conversation;
?? , ? sleep; A,
as the noise increased, amounted to about 62 dB(A) for the daytime activities and about 52 dB(A) on going to sleep. A significant difference in behaviour was observed with regard to the sites in Lyon and Marseilles, respectively. Thus windows were not closed to the same extent in Marseilles, at least for noise levels up to about 72 dB(A), presumably because of the milder climate. Above this critical noise level it appears that all subjects felt compelled to close their windows such that the climate no longer had any effect. As regards the transfer of activities susceptible to the effects of noise to quieter rooms, it ,was found that the critical noise level above which there was a significant response during the daytime period amounted to L, 3 68 dB(A). The activities mainly involved here were reading and work of an intellectual nature carried out in the home, these being activities that can often be transferred from one room to another without too much difficulty. On the other hand there was no significant transfer of activity so far as watching the television or sleeping was concerned. Clearly there are difficulties with regard to the transfer of these last two activities, either because of the lack of a spare room or because of the physical difficulties involved in moving an item of equipment such as a television set to another room. The effect of the noise on the use of balconies was determined by considering a number of relevant activities that are more or less affected by noise. Of these activities the only ones that are really affected by noise, and then only moderately, are those listed in Figure 6. In fact it was found that the subjects only indulged in these activities to a limited extent even when the noise levels in the vicinity of the balconies was very low (L, < 50 dB(A)). Thus only 23% of the subjects held any conversations on their balconies in spite of the low levels of noise that applied. It therefore seems likely that the use of balconies depends very largely on other factors such as the presence of sunshine, the size of the balcony and the degree of seclusion that is offered, and that the noise level is only of secondary importance. 3.2.2. Effect of noise on sleep and health The effect of noise on sleep has been the subject of a number of studies, particularly with regard to the physiological effects [ 151. This study however was more concerned with the identification of simple indicative parameters and the determination of critical noise levels. The indicative parameters were concerned with the conditions that can apply on going to sleep: time taken in getting to sleep, difficulties in getting to sleep, taking of
BEHAVIOUR
Figure
6. Percentage
PATTERNS
of balconies
DUE
TO
used for: ----,
TRAFFIC
flowers;
-,
165
NOISE
conversation:
- - -. lunch.
sleeping tablets and the extent to which noise results in the subjects waking up during the night. Table 3 gives the degree of correlation with the noise, the level of significance and the two noise levels above which there are significant increases in the effects, for each of the indicative parameters. These results as well as those obtained on carrying out a principal components analysis lead one to the following conclusions: noise appears to have a much more pronounced effect in waking people up than in preventing them from getting to sleep, this latter difficulty being more closely related to the age of the subjects; the interference with sleep leads to an appreciable increase in the taking of sleeping tablets although there appears TABLE
3
Some relationships between sleep and noise levels outside bedroom walls Night-time noise thresholds (during the day)
Correlations with Indicator
_~____ Percentage of people falling asleep within less than 20 min Difficulties in getting MO years
the
noise level __.__~ 0.65
Level of significance 1%
First threshold
Second threshold ss (65)
to sleep: 0.04 0.17
Not significant 1%
Percentage of people often and very often having difficulty in getting to sleep
0.73
< 1%
55 (65)
Percentage of people taking sleeping tablets on going to bed
0.76
< 1%
55 (65)
0.09 0.22
Not significant < 1%
0.86
< 1%
Being woken >50 years <50 years
up during
the night:
Percentage of people often and very often woken up during the night
55 (63)
166
J. LAMBERT,
F. SIMONNET
AND
M. VAL.L.ET
to be a stronger connection with age here than with the presence of noise ( 13% of people taking sleeping tablets for noise levels of SO dB(A) and 20% when the noise level amounts to 75 dB(A)). Although there is only a slight correlation between the noise and some of the indicative parameters it should be noted that the critical noise levels. above which there are more rapid increases in the interference with sleep, are the same for all of these parameters. Thus, to consider just two critical levels, there are rapid increases in the effects for all of these parameters above L, values of 45 and 55 dB(A) for the 00.00-05.00 hour period which correspond to L, values of 55 and 6.5 dB(A) for the 08.00-20.00 hour period. As to medicament consumption, not only on going to bed but also during the day, then, as shown in Figure 7, it was found that there are rather significant relations with the level of noise. If some subsidiary classifications of the subjects with regard to the 20 r-
5 I
O/d 50
55 dE(A)
Figure
L,,
7. Medicament
00.00-20.00
consumption
hours
versus noise
taking of sleeping tablets are considered it can be seen how this practice is related to sleeping difficulties. Thus subjects who have difficulties in getting to sleep are much more likely to take sleeping tablets: 33% compared with 10% in general and 57% when the subjects are more than 65 years of age. In this latter case, the presence of noise simply reinforces the behaviour, the percentage of subjects taking taking sleeping tablets rising to 69% for noise levels of L, z=65 dB(A). On the other hand, subjects that tend to get to sleep fairly quickly seldom take sleeping tablets, particularly if they are young (less than 5%). 3.2.3.
Items used in the home and expenditure on the dwelling itself
The results did not reveal any significant variations in the possession of items whose use can be affected by noise such as record players, radios, television sets and hi-fi assemblies, or in the average times spent in listening to such devices, which tend to remain the same whatever the noise level. As regards expenditure on the home or building itself it was necessary to make a distinction between the normal expenditure associated with the furnishing and upkeep of the different rooms and the comparatively large outlay involved in the fitting of sound proofing materials to the external faces of the rooms. Whereas the expenditure on the furnishing and upkeep of the different rooms did not appear to be affected by the level of noise, this was not the case with regard to expenditure on sound proofing where the noise level played a major role. Figure 8 shows clearly how the percentage of dwellings that have been sound proofed increases with the noise level.
BEHAVIOUR
PATTERNS
DUE
TO
TRAFFIC
NOISE
167
30 aJ $ 5 2 a”
zo-
IO-
0’.
50
’
55 dB(A)
Figure 8. Percentage
of sound proofed
60 L.,
65 08.00-20.00
dwellings versus noise. p,
70
75
hours Owners:
‘, tenants; - - -. total sample.
A number of different factors are involved here and if one considers the results concerning the sound proofing of the dwellings with respect to different criteria (see Figure 9) it will be seen that the following conclusions can be drawn. Noise level is the most important factor involved and the proportion of dwellings that have been sound proofed becomes significantly greater as the noise level rises above 66-68 dB(A) (24 in place of 8%). Income is only involved for noise levels of less than 66-68 dB(A). Thus it would seem that the lower levels of noise and the consequent effects are not regarded as being sufficiently objectionable for people to accept the considerable expenditure involved in sound proofing except for households where there is a high income (> 7000 French francs per month). For noise levels above 66-68 dB(A), however, the objectionable effects seem to be sufficiently great that people tend to regard sound proofing as a facility that needs to be provided regardless of cost. Owner-occupier or tenant: owner-occupiers have a different attitude than do the tenants here. Thus the former consider that expenditure on the provision of sound proofing is an investment which can increase the value of their property (see Figure 8). Length of occupation: people who have occupied their dwelling for a long time tend to be more ready to spend money on sound proofing than do people who have only recently taken up residence. This would seem to be in direct support of the claim that people do not get used to noise. 3.2.4.
Escaping from the home
The last type of behaviour where it was assumed that noise could be involved was that of escaping from the home. More precisely, the question to be answered was whether or not a high level of noise could result in an individual and his family leaving their premises. either for limited periods of time, that is, during the course of the day in the case of housewives or over the week-end in the case of the whole family (e.g., on visiting friends). or permanently, that is, moving to another dwelling. The results indicated that whereas the noise did not give rise to families going out any more, either during the week or at weekends (which would have been a useful indication of attempts to escape from the noise), it did lead to some families considering the possibility of moving. However, although the noise was involved to some extent here it did not appear to be the main reason for moving. The analysis of this type of response was delicate, namely the intention to move to another dwelling, but one can nevertheless draw the following conclusions.
168
_I. LAMBERT.
F. SIMONNET
AND
M. VALLE7
BEHAVIOUR
PATTERNS
DUE
TO
TRAFFIC
NOISE
169
The status of occupation of the dwelling has a dominant effect. Thus not only is it easier for a tenant, as opposed to an owner of a property, to move (no difficulties with regard to the selling of the property) but there may be other obvious reasons for moving apart from the question of noise (need to find more suitable accommodation, desire to purchase a house, etc.). On the other hand the amount of a low rent to be paid and the difficulty of finding equivalent accommodation can discourage a tenant from moving. Finally, there is an effect of noise which becomes more pronounced for levels above 66-68 dB(A) and when it is found that a low rent is not enough to prevent tenants from moving. Thus it would appear that there cannot be any monetary compensation for the higher noise levels. It should also be noted that the fact that he has sound proofed his dwelling is likely to discourage an occupant from moving. Thus the two behavioural responses of sound proofing the dwelling or moving, which are both more likely to arise for noise levels of more than 66-68 dB(A), can be regarded as alternative possibilities. 4. DISCUSSION The correlation between the noise level and the annoyance appears to be much greater than was the case for previous inquiries. There would appear to be three reasons for this higher correlation. First of all it is probable that the greater accuracy involved in the measurement of the noise and the determination of the L, values that were applicable in each case accounted for the much stronger relation. Seconaly, the fact that the sample was made up to a large extent of women confined to the home would have reinforced the correlation; thus Vallet in 1974 [6] established that there was a significant difference in the noise-annoyance correlation for the “inactive” subjects considered in isolation (r = O-47) than for the complete sample of subjects (r = 0.31). Finally, it is likely that one is beginning to witness the results of a greater awareness of noise on the part of the public; thus it should be noted that the correlation obtained in the case of recent inquiries, and more particularly in the case of that conducted by Bradley, appears to be significantly greater than that obtained as a result of inquiries that were conducted some 10 years ago. The possibility of transferring activities to quieter rooms is dependent on the following three conditions: the presence of two constrasting levels of noise within the dwelling; the size of the dwelling and the number of people in the family: for example, it is not possible to make use of a quieter room for sleeping if a room cannot be made available for this purpose; the nature of the activity to be transferred: one can make a comparison here between individual activities, such as reading or intellectual activities, that are undertaken at home and which can be readily transferred and family activities, such as watching the television and collective leisure activities. which cannot be undertaken in just any room of the dwelling. It would seem that the climate can have significant effects on the behaviour in response to noise. Thus it was found that there was a greater reluctance to close the windows to shut out the noise and to spend money on sound proofing in Marseilles than was the case for the subjects living in Lyon and this probably accounts for the generally greater degree of annoyance expressed by the subjects living in the former location (given that the internal noise levels would have been higher in the Marseilles dwellings). As has been seen, behavioural responses depend to a large extent on variables other than noise. Thus the responses can depend on individual characteristics, namely the age and family situation of the subject and on whether the subject is an owner-occupier or
170
J. LAMBEK7‘. F. SIMONNt-I‘ AND
M. VALLtI
tenant, or on what amounts to constraints which limit the action that can be taken in the presence of noise such as the amount of income and the size of the dwelling. Some responses can be direct reactions to the annoyance that is being experienced, such as the closing of windows to shut out the noise, while others can be directed at minimizing the effects, such as the sound proofing of the dwellings. Depending on the particular situation the responses can be closely related to one another (tendency to leave the premises at the weekends or plans to move to another dwelling in order to escape from the noise) or they can amount to alternative possibilities (moving to another dwelling or sound proofing of the existing accommodation). It should be appreciated that the analysis of all these possible responses is no easy matter and the subject therefore deserves to be considered in much more detail in the future, given its complexity and the difficulties in understanding what is involved.
5. CONCLUSION In this study it was attempted to assess the effects of traffic noise by considering the adaptive or evasive behavioural responses to such noise. The different indicative parameters that were considered are listed in Table 4 together with an indication of the critical levels above which the noise appears to have significant effects in each case.
TABLE Indicative
parameters
4
relative to road trafic
noise impact threshold
L,, (A) 08.00-20.00
I
60-62 dB(A)
7
50-52 dB(A) Percentage
of very and
h
66-68 dB(A)
63-65 dB( A)
L,, (A) 00.00-05.00
noise levels
69-70 dB( A)
h
53-55 dB(A) Annoyance
rather annoyed people: day period night period Expressed noisiness Effects on sleep and health People having difficulty getting to sleep People waking in the night People getting rapidly to sleep Leg troubles Digestion difficulties
Headaches
Sleeping tablets consumption Closing windows watching TV lecture sleep
for
Behaviour Transfer of activities to quieter rooms Moving to another dwelling Sound proofing the dwelling
Medicaments for heart troubles consumption
BEHAVIOUR
PAlTERNS
DUE
TO
TRAFFIC
NOISE
171
As a result of the study it is possible to come to the following conclusions. 1. Below 55 dB(A) for the daytime value of J!,,, it can be assumed that the noise gives rise to little or no disturbance and that the level of noise is such that activities that are most likely to be affected by noise can be carried out quite normally. 2. Between 55 and 60dB(A) the effects of the noise are still acceptable but people who are most sensitive to noise are beginning to be disturbed. 3. Between 60 and 65 dB(A) one begins to see some behavioural responses that are not as yet very forced (e.g., the closing of windows to shut out the noise). However, the effects with regard to sleeping and the degree of annoyance that is experienced increase very significantly. It is desirable that action be taken to reduce the noise level but the results of a cost-benefit analysis of such action will not necessarily be very positive, at least in the case of palliative measures such as the provision of sound barriers or the application of sound proofing treatment. 4. Above 65 dB(A) one begins to see compulsive behavioural responses which are indicative of severe disturbance due to the noise (transfer of activities to quieter rooms, sound proofing of dwellings, moving to other accommodation). Action by the public authorities in this case is not only desirable but essential particularly since in most cases the net economic benefit of any action has every chance of being positive for the community as a whole. Although these propositions are more restrictive than is the case for the current French recommendations (L, = 65 f 5 dB(A)) they are on the other hand in complete agreement with the recommendations of the Swiss Federal Office for the Protection of the Environment [16] and those put forward by the Environmental Protection Agency (EPA) of the U.S.A. ACKNOWLEDGMENTS This study was carried out at the request of the Centre d’Etude des Transports Urbains (Urban Transport Studies Centre) and IRT-CERNE express their thanks to this organization for their permission to publish the results of the work. Thanks are also due to Dr F. J. Langdon for his invaluable advice during the preparation of this paper. REFERENCES 1. A. C. MCKENNELL 1963 Aircraft Noise Annoyance around London (Heathrow) Airport SS, 337. London: Her Majesty’s Stationery Office. 2. F. J. LANGDON and I. D. GRIFFITHS 1968 JournalofSound and Vibration 8,16-32. Subjective responses to road traffic noise. 3. P. N. BORSKY 1961 WADD Technical Report, 60-689, AF 33 and 41. Community reactions to Air Force noise, I and II. 4. C. LAMURE and M. BACELON 1967 Cahiers du C.S.T.B no 88. La gke due au bruit de la
circulation automobile, une enqutte auprb des riverains d’autoroutes. 5. F. J. LANGDON 1976 Journal of Sound and Vibration 47, 243-282. Noise nuisance caused by road traffic in residential areas: Parts I and II. 6. M. VALLET, M. MAURIN, M. A. PAGE, B. FAVRE and G. PACHIAUDI 1978 Journal of Annoyance from and habituation to road traffic noise from Sound and Vibration 60,432-440. urban expressways. 7. M. A. JENKINS and J. PAHL 1975 Journal of the Acoustical Society of America 58, 1211-1221. Measurement of freeway noise and community response. 8. M. A. PAGE and J. M. ABRAMOVITCH 1976 IRTReport. Attitudes de la population devant un projet de protections acoustiques. Etude de cas: l’Hay-les-Roses. 9. J. M. ABRAMOVITCH 1977 ARPENT Report. Enqutte psychosociologique aux abords de l’ecran acoustique de l’Hay-les-Roses.
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_I. LAMBERT, F. SIMONNET
AND
M. VALLE'I
10. B. VOISIN 1977 ARPENTReporr. PrCCtude clinique des comportements dans I‘habitat soumts au bruit de circulation. 11. B. FAVRE 1975 IRT Report. MCthode de calcul automatique des niveaux de bruit de la
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