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.     

A theory of patterns of passby noise

Some people say they are annoyed by traffic noise. There is rather a lot of evidence to show that where traffic noise is louder, more people say they are annoyed by it. On the basis of this sort of evidence, there is a consensus that road traffic noise causes annoyance, but some studies have detected unexplained peaks of annoyance in quieter places, or a plateau of annoyance in high noise. Such anomalies may especially affect those sensitive to noise. The pattern of alternation of passby noise and background traffic noise explains the positioning in soundspace of anomalies variously reported at 60 dB(A) L_eq, 4000 NV and 1800 NHV. Such anomalies occur where there are regular or rapidly alternating patterns of passby noise.     

Road traffic noise levels, restrictions and annoyance in Greater Cairo, Egypt

This study concerns road traffic noise in Greater Cairo, the capital and the largest city in Egypt and the eleventh biggest city in the world. Extensive measurements were carried out in 21 sites in Greater Cairo. Restrictions were introduced to improve environmental conditions including: (i) a ban on horns, (ii) a ban on horns and trucks, (iii) a ban on horns, trucks and noisy buses. Equivalent noise levels (L_Aeq) were measured before and after these restrictions. The equivalent noise level was considerably reduced by the bans. This shows that the town planner can use various strategies to change the traffic composition in order to achieve quieter city environments. The degree of annoyance was measured by means of questionnaire. The results showed that there was a strong relationship between road traffic noise levels and the percentage of highly annoyed respondents.     

Industrial noise levels and annoyance in Egypt

Annoyance and increase of accident risk of workers from industrial noise levels in Egypt were studied. 683 workers from 15 Egyptian sites of industry, ranging from food to metal industry were evaluated. The goals of this study are to carry out measurements to evaluate industrial noise levels, are these levels exceeded the permissible levels set by Egyptian noise standard and policy to protect public health of workers?, to examine worker’s attitudes towards industrial noise, to know the relationship between industrial noise levels and degree of annoyance. Results showed that equivalent continuous noise levels ranged from 70 to 100 dB (A). Annoyance of respondents showed that 47.1% were highly annoyed, 5.8% their hearing were harmed. There was a strong relationship between industrial noise levels and percentage of highly annoyed respondents. By increasing industrial noise level possibility of workers to make accident was also increased. Respondents suggest less maximum daily exposure duration than those set by Egyptian law.     

The impact of urban noise on primary schools. Perceptive evaluation and objective assessment

This paper aims to assess the impact of environmental noise in the vicinity of primary schools and to analyze its influence in the workplace and in student performance through perceptions and objective evaluation. The subjective evaluation consisted of the application of questionnaires to students and teachers, and the objective assessment consisted of measuring in situ noise levels. The survey covered nine classes located in three primary schools. Statistical Package for Social Sciences was used for data processing and to draw conclusions. Additionally, the relationship of the difference between environmental and background noise levels of each classroom and students with difficulties in hearing the teacher’s voice was examined. Noise levels in front of the school, the schoolyard, and the most noise-exposed classrooms (occupied and unoccupied) were measured. Indoor noise levels were much higher than World Health Organization (WHO) recommended values: L_Aeq,30min averaged 70.5 dB(A) in occupied classrooms, and 38.6 dB(A) in unoccupied ones. Measurements of indoor and outdoor noise suggest that noise from the outside (road, schoolyard) affects the background noise level in classrooms but in varying degrees. It was concluded that the façades most exposed to road traffic noise are subjected to values higher than 55.0 dB(A), and noise levels inside the classrooms are mainly due to the schoolyard, students, and the road traffic. The difference between background (L_A95,30min) and the equivalent noise levels (L_Aeq,30min) in occupied classrooms was 19.2 dB(A), which shows that students’ activities are a significant source of classroom noise.     

Noise abatement schemes for shielded canyons

Access to quiet areas in cities is important to avoid adverse health effects due to road traffic noise. Most urban areas which are or can become quiet (L_A,eq < 45 dB) are shielded from direct road traffic noise. By transfer paths over roof level, many road traffic noise sources contribute to the level in these shielded areas and noise abatement schemes may be necessary to make these areas quiet. Two real life shielded courtyards in Göteborg have been selected as reference cases for a numerical investigation of noise abatement schemes. The selected areas are modelled as canyons with a road traffic noise source modelled outside the canyon by a finite incoherent line source, which is more realistic than both a coherent and an incoherent line source of infinite length. The equivalent sources method has been used for the calculations. For all studied noise abatement schemes in the shielded canyon, the reductions are largest for the lower canyon observer positions. Façade absorption is the most effective when placed in the upper part of the canyon and can typically yield a reduction of 4 dB(A). Constructing 1 m wide walkways with ceiling absorption reduces the level typically by 3 dB(A). These effects are most effective for narrower canyons. For treatments at the canyon roof, reductions are independent of the canyon observer position and amount to 4 dB(A) for a 1 m tall screen and 2 dB(A) for a grass covering of a saddle roof. Downward refracting conditions increase the levels for the lower canyon observer positions and higher frequencies. For sources located in canyons, abatement schemes therein are more effective for noise reduction in the shielded canyon than similar abatement schemes in the shielded canyon itself, given that all contributing source canyons are treated.     

The relationship between civil aircraft noise and community annoyance in Korea

Studies of community annoyance caused by civil aircraft noise exposure were carried out in 18 areas around Gimpo and Gimhae international airports in order to accumulate social survey data and assess the relationship between aircraft noise levels and annoyance responses in Korea. WECPNL, adopted as the aircraft noise index in Korea, and the percentage of respondents who felt highly annoyed (%HA) have been used to assess the dose-response of aircraft noise. Aircraft noise levels were measured automatically by airport noise monitoring system, B&K type 3597. Social surveys were carried out to people living within 100 m of noise measurement points. The Questionnaire used in the survey contained demographic factors, noise annoyance, interference with daily activities and health-related symptoms. The question relating to the aircraft noise annoyance was answered on an 11-point numerical scale. The randomly selected respondents who were aged between 18 and 70 years completed the questionnaire by themselves. In total, 705 respondents participated in the questionnaire. The results show that WECPNL, noise metric considering characteristics of event and intrusive noise, is more reasonable than L_dn, noise metric considering total sound, to assess the effects of aircraft noise on health. It is also shown that the annoyance responses caused by aircraft noise in Korea seems higher than those reported in other countries.     

Sleep disturbance by traffic noise: an experimental study in subjects' own houses using a portable CD player

The current study investigated the effect of noise on sleep in subjects' own houses using recorded traffic noises. A railway noise and two kinds of road traffic noise differing in level-fluctuations were used as stimuli. Subjects were exposed all night to the artificially controlled stimuli for 10 days through a portable compact disc (CD) player. The effect of noise on sleep was judged in three ways, namely whether the subject had switched off the CD player, a self-declaration of the subject based on a questionnaire, and the amount of arm movement of the subject during the night as measured by an actigraph. The results of the analysis of the self-declaration data showed that the thresholds where sleep disturbance began were 40-45 dB in for road traffic noise and about 35 dB for railway noise, which corresponded to 50-55 dB in L_A,Fmax of each train noise event. The results of the analysis of the actigraphy data showed a rapid increase in the incidence of mid-sleep awakening at sound pressure levels higher than 50 dB, for railway noise. However, neither of the road traffic noises showed such a tendency, as long as the sound pressure level was less than 55 dB, .     

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.     

Road traffic noise mitigation strategies in Greater Cairo, Egypt

This study concerns road traffic noise in Greater Cairo, Egypt. Road traffic is the most significant sources of noise in the city. Measurements of road traffic noise levels in Greater Cairo in September and October 2001, indicated that noise levels in city were higher than those set by the Egyptian noise standards and policy to protect public health and welfare in residential areas (L_Aeq=80 dB and higher were recorded). A social survey carried out simultaneously indicated that 73.8% of respondent residents were highly or moderately irritated by road traffic noise. In our paper we present (1) The results of road traffic noise measurements. (2) Egyptian noise standards and policy. (3) Results of the social survey. (4) Traffic congestion and traffic noise characteristics of Greater Cairo. (5) Thirty years of countermeasures taken. (6) Future mitigation strategies aiming for a quiet city.     

Annoyance and self-reported sleep disturbances due to structurally radiated noise from railway tunnels

In Norway, the requirement for structure borne noise from tunnels is L_pAFmax = 32 dB inside dwellings. According to the Norwegian Standard 8175 it is expected that up to 20% of the exposed population are disturbed by the noise at this level. However, the scientific basis for this noise limit is poor. The aim of this study was to determine the degree of annoyance and self-reported sleep disturbances as a function of L_pAFmax. In the present study, 521 dwellings exposed to structural sound from railway rock-tunnels were identified. A questionnaire was sent to one randomly selected person above 18 years of age from each dwelling. The results showed that both noise induced annoyance and reported sleep disturbances were significantly related to L_pAFmax. Other factors that increased the annoyance were high pass-by frequency of freight trains per day, and degree of sound insulation of the windows. At L_pAFmax = 32 dB, 20% were slightly or more than slightly annoyed, and 4% were moderately or more than moderately annoyed. According to the pre-existing assumption that up to 20% of the exposed population are disturbed by the noise at this level, the present results give support to the Norwegian noise limit L_pAFmax = 32 dB inside dwellings of structure borne noise from railway tunnels.     

A survey of community attitudes towards noise near a general aviation airport

This paper describes a community attitudinal noise survey performed in the vicinity of the Decatur, Illinois Airport. Two hundred thirty-one respondents were drawn from four distinct noise zones in populated areas near the airport. The day/night average sound levels (DNL) ranged from 44-66 dB. The area is otherwise quiet, residential with large (1/2 acre) lots. The primary analysis arrayed the percent of respondents highly annoyed versus DNL. Good agreement was found between the results of this survey and the general relation developed by Schultz from surveys worldwide, primarily in the vicinity of large commercial airports and highways. In addition, reasonable comparisons were found between respondent estimates of the number of aircraft operations and actual traffic counts. It was also found that respondents who were highly annoyed by aircraft noise were three to four times as likely to be highly annoyed by some other noise than were other respondents.     

DIFFERENT EFFECTS OF ROAD TRAFFIC NOISE AND FROGS' CROAKING ON NIGHT SLEEP

This study was designed to assess the effects of road traffic noise and frogs' croaking on the objective and subjective quality of sleep in a laboratory. The subjects were seven male students aged 19-21 years. They were exposed to recorded road traffic noise and frogs' croaking, with 49·6 and 49·5 dB(A)L_Aeq , and 71·2 and 56·1 dB(A) L_Amax, respectively. The background noise in the experimental room was 31·0 dB(A) L_Aeq. The sleep EEG was recorded according to standard methods. The sleep polygraphic parameters examined were the percentage of sleep stage relative to the total sleep time (%S1, %S2, %S(3+4), %SREM, %MT), total sleep time, sleep onset latency, and awakening during sleep in minutes and sleep efficiency. A structured sleep rating questionnaire (OSA), was administered to the subjects after they awakened. The %S2 increased and the %SREM decreased during exposure to road traffic noise. However, no significant effect of exposure to frogs' croaking was observed on any of the polygraphic sleep parameters. The subjective quality of sleep was degraded more by exposure to road traffic noise than that to frogs' croaking.     

Reactions to railway noise in Denmark

People's reactions to railway noise were studied along seven Danish railway lines with traffic intensities from 30 to about 300 trains per 24 hours. The calculated sound levels varied between 43 and 71 dB(A) for L_Aeq,24h and between 78 and 102 sB(A) for L_Amax. 615 persons were interviewed. One third of these felt strongly or somewhat annoyed by the railway noise. The relations between the noise level and the extent of annoyance or various kinds of behaviour (telephone conversation, TV-listening, opening of windows, sleep, etc.) were found. The relations were found for both L_Aeq,24h and L_Amax, but the correlation for L_Amax is generally bad. Noise in the evenings was found to be more annoying than noise in other daytime periods. More than half of the interviewees answered that goods trains especially were a problem. People exposed to noise at their place of work seem to feel more annoyed by railway noise than other people.     

COMPARISON OF COMMUNITY RESPONSE TO ROAD TRAFFIC NOISE IN JAPAN AND SWEDEN—PART I: OUTLINE OF SURVEYS AND DOSE-RESPONSE RELATIONSHIPS

To investigate cross-cultural differences in the community response to road traffic noise, social surveys were conducted in Gothenburg, Sweden, and Kumamoto and Sapporo, Japan, using the same questionnaire and noise measurement method. Typical residential areas with detached houses and apartments were selected as the target areas in each city. The questionnaire comprised 40 questions relating to environmental, housing and personal factors. The key questions concerned annoyance caused by road traffic noise. The total numbers of respondents were 1142 in Gothenburg, 837 in Kumamoto and 780 in Sapporo. The response rates were 68·8, 69·3 and 57·5% respectively. After the questionnaires were completed, noise measurements were made in each area. Community responses were compared on the basis of the dose-response relationships. There were no systematic differences between community responses in Sapporo and Kumamoto, which have the same culture. People living in detached houses in Gothenburg were more annoyed by the same road traffic noise than the people living in Japanese cities. There were no systematic differences among the three cities with regard to activity disturbances indoors, but significant disturbance of activities and resting in gardens or on balconies was noted in Gothenburg. The difference in activity disturbance was due to the differences between lifestyles in the two countries. People living in detached houses were more annoyed by the house vibration caused by road traffic than those living in apartments and people were annoyed by the exhaust from road traffic to the same extent as noise.     

The differing annoyance levels of rail and road traffic noise

The results of a study on the relative annoyance by rail or road traffic noise in urban and rural areas are reported. Fourteen areas with rail and road traffic noise with differing levels of loudness (L_eq) were investigated. The annoyance was assessed by means of a questionnaire. The analysis of the relationship between annoyance and L_eq—performed separately for rail and road traffic noise—shows that the same amount of annoyance is reached for railway traffic noise at L_eq levels 4–5 dB(A) higher than for road traffic noise (railway/traffic noise “bonus”). The estimation for the difference values vary for the different variables of annoyance. Furthermore, the difference levels tend to be higher in urban than in rural areas.     

The relationship between traffic noise and insomnia among adult Japanese women

To clarify the relationship between traffic noise and insomnia, the authors conducted a survey and measured the actual sound level of noise in an urban area. Questionnaires were distributed to adult women who lived within 150 m from two major roads and were completed by 648 of the 1286 subjects (50.4%). The area was divided into three zones according to distance from the road (more than 50, 20-50 and 0-19.9 m). Fifty-seven subjects (8.8%) were classified as having insomnia. Average values of sound level at distances of 20, 50, and 100 m from the major road were L_eq 64.7, 57.1, and 51.8 dBA, respectively. Overall, there were no significant differences among the three zones in the prevalence of insomnia and no association between distance from the road and insomnia. However, the result from a sub-data set of the subjects who lived in the areas that showed decreasing noise level as the distance from the main road increased showed that distance from the road was associated with insomnia. This study suggests that researchers should consider the actual traffic situation and its sound level in epidemiological studies about the effects of traffic noise on insomnia.     

A rail noise prediction model for the Tehran-Karaj commuter train

Rail noise prediction models enable consideration of different scenarios for the optimal management of noise prevention and mitigation. This project is aimed at developing an equation that enables computation of L_A,max for the Tehran-Karaj commuter train, a type of Diesel-Electric Locomotive. The form of the proposed model is derived from equations for predicting L_A,max for a single locomotive pass-by, proposed in the manual prepared by Harris Miller Miller & Hanson Inc. for the US Federal Transit Administration, and in the French rail noise prediction model. The algorithm for predicting L_A,max for the Tehran-Karaj commuter train has been developed on the basis of the 50 measurements from 5 locations at distances of 25 m, 35 m, 45 m, 55 m, and 65 m from the centre of the track and at a height of 1.5 m. In the field measurements, the reference distance and the reference vehicle speed have respectively been set equal to 25 m and 80 km per hour. The reference L_A,max, length and the speed correction coefficients have been estimated from the field measurements and have been found to be 86.2 dB(A), 11.3, and 18.4 respectively. The fitness test (Kolmogorov-Smirnov) and regression analysis indicate satisfactory results.     

Acoustic insulation capacity of Vertical Greenery Systems for buildings

Vertical Greenery Systems (VGS) are promising contemporary Green Infrastructure which contribute to the provision of several ecosystem services both at building and urban scales. Among others, the building acoustic insulation and the urban noise reduction could be considered. Traditionally vegetation has been used to acoustically insulate urban areas, especially from the traffic noise. Now, with the introduction of vegetation in buildings, through the VGS, it is necessary to provide experimental data on its operation as acoustic insulation tool in the built environment. In this study the acoustic insulation capacity of two VGS was conducted through in situ measurements according to the UNE-EN ISO 140-5 standard. From the results, it was observed that a thin layer of vegetation (20–30 cm) was able to provide an increase in the sound insulation of 1 dB for traffic noise (in both cases, Green Wall and Green Facade), and an insulation increase between 2 dB (Green Wall) and 3 dB (Green Facade) for a pink noise. In addition to the vegetation contribution to sound insulation, the influence of other factors such as the mass factor (thickness, density and composition of the substrate layer) and type of modular unit of cultivation, the impenetrability (sealing joints between modules) and structural insulation (support structure) must be taken into account for further studies.