Acoustical, sensory, and psychological research data and procedures for their use in predicting effects of environmental noises

A demonstration field-research study reveals that aircraft noise measured at two one-story houses is approximately 9 dB less attenuated from measured outdoor levels than is street traffic noise, and, found in other studies, approximately 14 dB less than railway noise. Comparable differences are found between these noises from the application of basic acoustical formulas for quantifying attenuations that occur on site of one- and two-story houses. Reasonably consistent with those findings are results from attitude surveys showing that daily exposure levels of aircraft must be approximately 8 dB less than levels of street traffic noise, and approximately 13 dB less than levels of railway noise to be perceived as an equal cause of annoyance and related adverse effects. However, USA government guidelines recommend that equal exposure levels of noise measured outdoors from vehicles of transportation should be considered as being equally annoying. Changes in present USA noise-measurement procedures and noise-control guidelines are proposed that provide more accurate predictions of annoyance, related adverse effects, and criteria for setting "tolerable" limits of noise exposure in residential areas. Key acoustical and psycho-acoustical principles and data pertaining to predicting correlations between dosages of environmental noises and its effects on people and land noise zoning in residential communities are examined.     

The response to railway noise in residential areas in Great Britain

The effects of railway noise on residents have been measured with a combined social survey (1453 respondents) and noise measurement survey (over 2000 noise measurements) at 403 locations in 75 study areas in Great Britain. In the analysis of the data methods have been used which take into account many typical noise survey problems including noise measurement errors, unique locality effects and the weakness of the noise annoyance relationship. Railway noise bothers 2% of the nation's population. Approximately 170 000 people live where railway noise levels are above 65 dB(A) 24 hour L_eq. Annoyance increases steadily with noise level; thus there is no particular “acceptable” noise level. Railway noise is less annoying than aircraft or road traffic noise of equivalent noise level, at least above 50 to 65L_eq. Noise is rated as the most serious environmental nuisance caused by railways. Maintenance noise is rated as a bigger problem than passing train noise. Vibration is the most important non-noise problem. Reactions to vibrations are related to distance from route, train speed and number of trains. The railway survey's highly stratified, probability sample design with many study areas makes it possible to evaluate the effects of area characteristics on reactions. The 24 h L_eq dB(A) noise index is more closely related to annoyance than are other accepted noise indices examined. There is no support for ambient noise level or night-time corrections. Thirteen railway operation characteristics were examined. One, the type of traction, has a strong effect on reactions after controlling for L_eq (overhead electrified routes are the equivalent of about 10 dB less annoying at high noise levels). Three indicators of railway ancillary noises and non-noise environmental nuisances affect annoyance but most operational characteristics have no effect. The effects of over 35 demographic, attitudinal and neighbourhood characteristics on annoyance are examined. Though most objective characteristics of neighbourhoods and respondents are not correlated with annoyance, three do decrease annoyance (older dwellings, older respondents, and life-time residence). The attitudes which affect annoyance with railway noise are not general ones about railways as transportation sources, but rather ones which are specific to the neighbourhood setting or to railways as environmental intrusions in the neighbourhood. Such attitudes often have less effect on annoyance at low noise levels. In such cases it is the reactions of the more annoyed types of people which are most closely related to noise level.     

Laboratory annoyance and different traffic noise sources

The acute annoyance reaction to different noise sources (lorries, aircraft, mopeds and trains) was investigated in a laboratory experiment. Students were exposed to different noise climates at noise levels 70 and 80 dB(A) for 25 minutes, and their reactions were subsequently assessed by using a questionnaire. Their general sensitivity to noise was also evaluated. The results demonstrated that L_eq gave the best correlation with annoyance. However, lorry noise was found to be less disturbing than aircraft noise at the same L_eq value. This was more pronounced if the different noises were compared at equal peak dB(A) levels. The results suggest that other factors such as the irregularity of the noise or the individual experience of the noise are of importance for the annoyance reaction. A relationship was found between the general annoyance score and annoyance reactions in the laboratory. Questionnaires could thus be a suitable tool for identifying noise sensitive persons.     

Some developments in community response research since the second international workshop on railway and tracked transit system noise in 1978

As far as human responses to railway noise are concerned, knowledge has increased considerably since the Second International Workshop on Railway and Tracked Transit System Noise was held in Lyon, France, in October 1978. Only some developments are mentioned in this article. Concerning land use planning some evidence became available that in maintaining or recovering a certain amount of well-being the concept of noise zoning deserves most attention, and that applying heavier sound insulation measures is not sufficient in solving the problem of noise annoyance. About the influence of background noise on annoyance, data from railway noise surveys are not conclusive. Whether or not habituation to noise occurs seems to be dependent on the way it has been made operational. Neither the often used self-reported habituation nor length of residence appears to have a clear relation with annoyance. Noise from shunting yards appears to be very annoying, compared with noise from through trains, road traffic and aircraft. The characteristics of the noise causing this relatively high degree of annoyance are still subject to study. “Normal” through trains cause less annoyance than road traffic and aircraft, the noise levels being equal. Some specific disturbances, however, like for instance being disturbed while watching television or having a conversation, occur at lower noise levels with railway noise than with road traffic noise.     

The relationship between railway noise and community annoyance in Korea

A study of community annoyance caused by exposures to railway noise was carried out in 18 areas along railway lines to accumulate social survey data and assess the relationship between railway noise levels and annoyance responses in Korea. Railway noise levels were measured with portable sound-level meters. Social surveys were administered to people living within 50 m of noise measurement sites. A questionnaire contained demographic factors, degree of noise annoyance, interference with daily activities, and health-related symptoms. The question relating to noise annoyance was answered on an 11-point numerical scale. The randomly selected respondents, who were aged between 18 to 70 years of age, completed the questionnaire independently. In total, 726 respondents participated in social surveys. Taking into consideration the urban structure and layout of the residential areas of Korea, Japan, and Europe, one can assume that the annoyance responses caused by the railway noise in this study will be similar to those found in Japan, which are considerably more severe than those found in European countries. This study showed that one of the most important factors contributing to the difference in the annoyance responses between Korea and Europe is the distance between railways and houses.     

Total annoyance from an industrial noise source with a main spectral component combined with a background noise

When living close to an industrial plant, people are exposed to a combination of industrial noise sources and a background noise composed of all the other noise sources in the environment. As a first step, noise annoyance indicators in laboratory conditions are proposed for a single exposure to an industrial noise source. The second step detailed in this paper involves determining total annoyance indicators in laboratory conditions for ambient noises composed of an industrial noise source and a background noise. Two types of steady and permanent industrial noise sources are studied: low frequency noises with a main spectral component at 100 Hz, and noises with a main spectral component in middle frequencies. Five background noises are assessed so as to take into account different sound environments which can usually be heard by people living around an industrial plant. One main conclusion of this study is that two different analyses are necessary to determine total annoyance indicators for this type of ambient noise, depending on the industrial noise source composing it. Therefore, two total annoyance indicators adapted to the ambient noises studied are proposed.     

Effect of background noise levels on community annoyance from aircraft noise

A study of community annoyance caused by exposures to civil aircraft noise was carried out in 20 sites around Gimpo and Gimhae international airports to investigate the effect of background noise in terms of dose-effect relationships between aircraft noise levels and annoyance responses under real conditions. Aircraft noise levels were mainly measured using airport noise monitoring systems, B&K type 3597. Social surveys were administered to people living within 100 m of noise measurement sites. The question relating to the annoyance of aircraft noise was answered on an 11-point numerical scale. The randomly selected respondents, who were aged between 18 and 70 years, completed the questionnaire independently. In total, 753 respondents participated in social surveys. The result shows that annoyance responses in low background noise regions are much higher than those in high background noise regions, even though aircraft noise levels are the same. It can be concluded that the background noise level is one of the important factors on the estimation of community annoyance from aircraft noise exposure.     

Annoyance reactions due to railway noise

Social survey studies to assess the presence of general annoyance were made in different areas exposed to railway noise. The results show that an increase in the number of passing trains increases annoyance up to a certain level, after which a levelling off takes place. Hence, there is no real annoyance in areas exposed to a maximum of 50 train passages/24 hours until the noise level reaches above 85 dB(A). If, on the other hand, train passages are 60 or more, annoyance increases according to the dB(A) level.     

Level discrimination of frozen and random noise

This paper examines how the difference limen for level, delta L, is affected by stimulus bandwidth and variability. The delta L's were measured in three normal listeners using an adaptive two-interval, forced-choice procedure. The 30-ms stimuli were a 3-kHz tone and nine noise bands with half-power bandwidths ranging from 50 Hz-12 kHz. Except for the 12-kHz bandwidth, which was a low-pass noise, the noise bands were centered at 3 kHz. The delta L's were measured for both frozen and random noises presented at 30, 60, or 90 dB SPL overall. For frozen noises, the same sample of noise was presented throughout a block of 50 trials; for the random noises, different samples of noise were used in each interval of the trials. Results show that the delta L's are higher for random than for frozen noises at narrow bandwidths, but not at wide bandwidths. The delta L's for frozen narrow-band noises decrease with increasing level and are similar to those for the pure tone, whereas the delta L's for wideband noises are only slightly smaller at 90 than at 30 dB SPL. An unexpected finding is that the delta L's are larger at 60 than at 30 dB SPL for both frozen and random noises with bandwidths greater than one critical band. The effect of bandwidth varies with level: The delta L's decrease with increasing bandwidth at low levels, but are nearly independent of bandwidth at 90 dB SPL. The interaction of bandwidth and level is consistent with the multiband excitation-pattern model, but the nonmonotonic behavior of delta L as a function of level suggests modifications to the model.     

Effect of season and meteorological conditions on community noise annoyance

More than 80 000 residents' responses to transportation noise from 42 studies conducted at different times of year provide statistical estimates of the effects of season and meteorological conditions on community response to noise. The strongest evidence for a seasonal effect comes from 7 years of continuous daily interviewing of nationally representative probability samples in the Netherlands. Long-term annoyance with noise is slightly, but statistically significantly, higher in the summer than in the winter. Analyses of 41 other surveys drawn from diverse countries, climates, and times of year also provide evidence that noise annoyance varies over the year, is increased by temperature, and may be increased by more sunshine, less precipitation, and reduced wind speeds. These findings are not sufficiently precise to determine whether the apparent relationships with meteorological conditions are only the result of seasonal variations or are also the result of differences in the climate at different locations. There is not consistent evidence that the meteorological conditions on the day of the interview or the immediately preceding days have any more effect on long-term noise annoyance measures than do the conditions over the immediately preceding weeks or months.     

Towards a unified system of noise assessment

Different indices are in current use for expressing the nuisance value of successions of noises, according to the type of noise. It is shown that a single index, termed noise pollution level, accommodates the experimental results of surveys of aircraft and of motor vehicle noise. The same formula satisfactorily explains the results of laboratory tests in which noise intensity is traded against duration to maintain equal impressions of objectionableness. The index is based on two terms, one representing the equivalent continuous noise level on the energy basis, and the other representing the augmentation of annoyance when fluctuations of noise level occur. Practical and theoretical implications of the index are discussed.     

Road traffic noise - the relationship between noise exposure and noise annoyance in Norway

Exposure-effect relationships between the level of road traffic noise at the most exposed side of a dwelling's façade and the residents' reactions to road traffic noise have been estimated. The relationships are based on five Norwegian socio-acoustic studies featuring 18 study areas from two cities and a total of near 4000 respondents. The survey questionnaires distinguish between noise annoyance experienced right outside the apartment and when indoors. Exposure-effect relationships for all degrees of annoyance are estimated simultaneously from ordinal logit models. These predict road traffic noise annoyance when right outside the apartment and when indoors, respectively, as a function of the road traffic noise level outside the most exposed façade. Separate analyses indicate that Norwegians react stronger to road traffic noise than results from a recent compilation of socio-acoustic surveys would lead one to believe. People having inferior single glazing windows report higher indoor annoyance.     

Railway noise and vibration annoyance in residential areas

This paper summarizes the results from the 1975 British railway noise study. Noise from railways does cause annoyance and interfere with activities. People in Great Britain appear to find high levels of railway noise to be somewhat less annoying than high levels from other sources. L_eq is as closely related to annoyance as any other index examined. Since annoyance increases steadily with noise level there is no particular “acceptable” railway noise level. Overhead electrified routes appear to be less annoying than diesel routes at the same noise levels. Through train noise, maintenance noise and vibration are the most widely noticed problems associated with railways in residential areas.     

Comparison of dose-response relationships between railway and road traffic noises: the moderating effect of distance

It has been found in European studies that railway noise causes less annoyance than road traffic noise. However, recent Japanese studies have shown that there is no systematic difference in dose-response relationships between railway and road traffic noises. In general Japanese houses are situated closer to railways or roads than European houses. The purpose of the study was to investigate whether the distance from noise source to houses influences community responses to railway and road traffic noises. A re-analysis was made of data from social surveys on community responses to railway and road traffic noises, which have been obtained from 1994 to 2001 in Kyushu, a warmer area of Japan and Hokkaido, a colder area. The results showed that the annoyance in areas close to railways was greater than that in distant areas, while there was no difference in dose-response relationships for road traffic noise between both areas. Considering the situation of houses in Europe and Japan, it is expected that the annoyance caused by railway noise is more severe in Japan than in Europe. The distance from noise source to houses may be one of the causes of the difference in community responses between Europe and Japan.     

Comparison of models to predict annoyance from combined noise in Ho Chi Minh City and Hanoi

Seven models were compared in terms of the ability to predict the annoyance due to the combination of aircraft and road traffic noises on the basis of data collected around airports in Ho Chi Minh City and Hanoi, Vietnam. The 24-h average sound levels L_Aeq,24h and unweighted means of annoyance scores for aircraft, road traffic, and combined noise were used to solve the regression equations for the seven models. The results indicate that road traffic noise exposure and annoyance were more than those of aircraft noise at almost all sites in both Ho Chi Minh City and Hanoi. Among the considered models, the dominant source model yielded the highest coefficients of determination, with R² values of 0.82 and 0.90 for surveys in Ho Chi Minh City and Hanoi, respectively. These results suggest that the dominant source model is the most useful model in the vicinity of those airports in Vietnam where road traffic noise is more dominant than aircraft noise. This is convenient for situations in which dose-response curves are established separately for different noise sources.     

Community reaction to aircraft noise: time-of-day penalty and tradeoff between levels of overflights

A decrease in the level of sound events can compensate for an increase in the level of other events, but noise metrics assume different tradeoffs. Noise metrics also differ in the penalty applied to noise in the evening and to noise in the night, and in the definition of these periods. These two aspects of noise metrics, i.e., the tradeoff and the penalty for the nighttime (23-7h), are investigated. A general model of the relation between SELs of sound events (aircraft overflights) and noise annoyance is presented which allows for a wide range of tradeoffs and time-of-day penalties. The (tradeoff and time-of-day penalty) parameters of the model are fitted to the data from an aircraft noise study conducted around Amsterdam Airport Schiphol, which is especially suited for investigating the tradeoff and time-of-day penalties. It was found that in this study the tradeoff between the levels of events in metrics based on L(Aeq)'s, such as L(Aeq)(24 h), DNL, and DENL, is approximately correct for the prediction of noise annoyance. Furthermore, it was found that the strongest correlation with annoyance is obtained with a nighttime penalty of circa 10 dB. No suitable data were available for further tests of the tradeoff. The result with respect to the nighttime penalty was weakly further supported by the outcome of analyses of the original data from four other aircraft noise surveys (one survey conducted around British airports, and three coordinated surveys carried out around Paris Orly, Amsterdam Schiphol, and Glasgow Abbotsinch).     

Community responses to road traffic noise in Hanoi and Ho Chi Minh City

Vietnam is a developing country in southeast Asia, and its environment has been seriously affected by industrialization and urbanization. In large cities like Hanoi (northern Vietnam) and Ho Chi Minh City (southern Vietnam), noise emission from road traffic has been found to be a serious concern among general public. In 2005 and 2007, two large-scale socio-acoustic surveys of community response to road traffic noise were conducted to investigate human reactions to road traffic noise in these cities; the sample sizes were 1503 people in Hanoi and 1471 in Ho Chi Minh City. The noise exposure levels (L_den) were 70–83 dB in Hanoi and 75–83 dB in Ho Chi Minh City. Noise annoyance was estimated using standardized annoyance scales. For both cities, dose–response relationships were established between L_den and the percentage of highly annoyed respondents. Compared to annoyance responses of European people, Vietnamese were less annoyed by road traffic noise by about 5 dB. Hanoi respondents seemed to be more annoyed by noise than Ho Chi Minh City respondents. Conversation and sleep disturbances were not as serious as expected in either city. Furthermore, window orientation in the home was found to affect activity disturbances.     

Influence of noise sensitivity on annoyance of indoor and outdoor noises in residential buildings

A survey and a laboratory experiment were conducted to investigate the influence of noise sensitivity on the annoyance caused by indoor residential noises and outdoor traffic noise. Results showed that noise sensitivity significantly influenced the annoyance level caused by both indoor and outdoor noise, consistent with previous studies on transportation noise. Annoyance level was significantly correlated with sensitivity in both the survey (r = 0.42–0.48 and 0.35 for indoor and outdoor noises, respectively) and the laboratory experiment (r = 0.25 and 0.14 for indoor and outdoor noises, respectively), in which noise exposure was controlled at 50 dBA. The correlation coefficient for indoor noise was higher than that for outdoor noise and was also higher than the average values (r = 0.3 and 0.22 for uncontrolled and controlled noise exposures, respectively) calculated using the results of several previous studies on outdoor transportation noise. Sensitivity was found to have a greater influence on the percentage of people who were highly annoyed by the indoor noise than it did on those affected by the outdoor noise.