Investigation of the dose-response relationship for road traffic noise in Assiut, Egypt

A field study has been carried out in urban Assiut city, Egypt. The goals of this study are: (1) to carry out measurements to evaluate road traffic noise levels, (2) to determine if these levels exceeds permissible levels, (3) to examine people’s attitudes towards road traffic noise, (4) to ascertain the relationship between road traffic noise levels and degree of annoyance. The measurements indicate that traffic noise noise levels are higher than those set by Egyptian noise standards and policy to protect public health and welfare in residential areas: equivalent continuous A - weighted sound pressure levels (L_A eq) = 80 dB and higher were recorded, while maximum permissible level is 65 dB. There is a strong relationship between road traffic noise levels and percentage of highly annoyed respondents. Higher road traffic noise levels mean that the percentage of respondents who feel highly annoyed is also increased.     

External and internal noise surveys of London primary schools

Internal and external noise surveys have been carried out around schools in London, UK, to provide information on typical levels and sources to which children are exposed while at school. Noise levels were measured outside 142 schools, in areas away from flight paths into major airports. Here 86% of the schools surveyed were exposed to noise from road traffic, the average external noise level outside a school being 57 dB L(Aeq). Detailed internal noise surveys have been carried out in 140 classrooms in 16 schools, together with classroom observations. It was found that noise levels inside classrooms depend upon the activities in which the children are engaged, with a difference of 20 dB L(Aeq) between the "quietest" and "noisiest" activities. The average background noise level in classrooms exceeds the level recommended in current standards. The number of children in the classroom was found to affect noise levels. External noise influenced internal noise levels only when children were engaged in the quietest classroom activities. The effects of the age of the school buildings and types of window upon internal noise were examined but results were inconclusive.     

Estimating traffic noise for inclined roads with freely flowing traffic

Traffic noise measurements on the kerbs of 19 independent inclined trunk roads with freely flowing traffic within the residential areas of Hong Kong are carried out in the present investigation. The performance of the existing noise prediction models in predicting traffic noise from inclined roads is evaluated. By regression analysis and simple physical consideration of the traffic noise production mechanisms, formulae for the prediction of the L_A10, L_A50, L_A90 and L_Aeq are developed or re-calibrated. Results suggest tyre noise has the major contribution to the overall noise environment when the source is an inclined trunk road. Also, the road gradient is found to have a higher contribution to the traffic noise than assumed in the existing models, but becomes unimportant when the background noise level L_A90 is concerned.     

Environmental noise pollution in the city of Curitiba, Brazil

This paper presents the results obtained in a study on environmental noise pollution in the city of Curitiba, Brazil. The equivalent sound level values—L_{Aeq, 2hr}—were measured and tabulated for 1000 locations spread over the urban zones of the city of Curitiba. It has been found out that 93.3% out of the locations display during the day equivalent sound levels over 65 dB(A), and 40.3% out of the total number of locations measured display during the day extremely high values of equivalent sound levels: over 75 dB(A).     

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.     

Influence of turbulence on train noise

The subject of this paper is the long distance propagation of train noise. The sound exposure level of train noise L_AE was measured. To describe the results of measurements, a semi-analytical model was used. It takes into account the wave-front divergence, air absorption, ground effect, and the turbulence destroying the coherent nature of the ground effect. The model contains three adjustable parameters that must be estimated at the site. To verify the model, we performed measurements of L_AE at the distance D = 450 m from the train track center. The difference between the calculated and measured mean values of L_AE equals 1.3 dB.     

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.     

Community response to aircraft noise in Ho Chi Minh City and Hanoi

To formulate Vietnamese and global noise policies, social surveys on community response to aircraft noise and combined noise from aircraft and road traffic were carried out in Ho Chi Minh City from August to September 2008 and in Hanoi from August to September 2009. In total, 1562 and 1397 responses were obtained in Ho Chi Minh City and Hanoi, respectively. The aircraft noise was measured for seven successive days, and the combined noise was measured for 24 h. Aircraft and combined noise exposures ranged from 53 to 71 dB and 73 to 83 dB L_den in Ho Chi Minh City and from 48 to 61 dB and 70 to 82 dB L_den in Hanoi, respectively. The dose–response curve for aircraft noise for Vietnam was established and fitted onto the curve for the European Union. For the same noise exposure, the aircraft noise annoyance in Hanoi was higher than that in Ho Chi Minh City because of the lower background noise level in Hanoi.     

Evaluation and analysis of the environmental noise of Messina, Italy

In this paper, the results of a study on the environmental noise pollution of the city of Messina (Italy) are presented. The investigation has included a preliminary classification of the territory in six acoustically homogeneous areas according to Italian noise regulations. On the basis of the resultant acoustic zoning 35 sites were selected for an experimental survey. This last has been carried out by extensive measurements of the main indexes for noise pollution (L_eq, L₁, L₁₀, L₅₀, L₉₀, L₉₉) and of the traffic flow and composition. Results indicate that: (a) main roads of Messina are overloaded by traffic flow during day-time period and that in all the examined sites daily average sound levels due to road traffic exceed environmental standards by about 10 dBA; (b) environmental noise exhibits a certain degree of spatial variance resulting primarily from the peculiar geo-morphological structure of the town and from the transport infrastructure and (c) more than 25% of residents should be highly disturbed by road traffic noise.     

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 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.     

Appraisal of Urban Road Traffic Noise in tier-II City (Surat City), India

Urban road traffic noise pollution has always been identified as a severe problem that affects urban populants. In developing nation, road traffic noise pollution depends on the composition of heterogeneous traffic composition. These traffic compositions contain vehicles, which have different sizes, speeds variations, a different dimension of vehicles. Environmental noise measurements have been carried out during day-time and night-time in different locations of tier-II city of India. The noise levels have been continuously measured over 24 h periods using kimo DB 300 class-2 noise level meter. The data contained in this research paper represent 768 measurement hours. All the information has been used to investigate the time patterns of the noise levels under a wide range of different conditions and to study the relationships between noise levels and traffic in urban areas. Maximum L_Aeq was observed 73.3 dB(A) at B₁₄ location and the minimum was recorded 65.7 dB(A) at C₃ location, which was greater than the central pollution control board (CPCB) prescribed limits during night time. A major reason for the generation of road traffic noise is due to the equal composition of 2-wheeler and 4-wheeler on the arterial road and heavy vehicles were recorded during morning peak and evening peak even though they are prohibited during peak hours.     

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.     

Laboratory study of the influence of noise level and vehicle number on annoyance

A laboratory study has been carried out to examine the relationships between annoyance and the level of road noise made up of background noise with emergent noisy truck passages. The annoyance caused to test persons was examined in experimental situations for periods of 30 minutes. There were two independent variables: the number of truck passages varied from three to 30, and the categories of overall noise level (L_eq for road noise) were 50, 55 and 60 dB(A). Generally, the results showed that for a constant L_eq level, annoyance increases with the number of truck passages as far as a certain threshold, where it tends to stabilize; for a constant number of truck passages, the annoyance increases with the L_eq level. It is found that although the index L_eq is a better criterion of annoyance than the number of truck passages a composite index with the general form αL_eq + β log N nevertheless appears to be more reliable in predictions.     

Estimation of the long term average sound level from hourly average sound levels

It is shown how to estimate the long-term average sound level, L_AeqLT (for free flowing road traffic) from measurements of the hourly A-weighted equivalent sound level, L_Aeq1h. To estimate the parameters of the model which describe noise emission and attenuation, concurrent measurements of L_Aeq1h at two distances from the considered road are needed. A semi-empirical formula is derived for L_AeqLT approximation. Also the uncertainty of this approximation is given as a function the distance from the road and receiver height.     

Traffic background level and signal duration effects on aircraft noise judgment

The effects of traffic background noise on the judged noisiness of aircraft flyover events has been further examined in the study reported here. A series of 72 flyover events were assessed by a jury of 35 observers, during 12 separate listening sessions conducted in a controlled test area designed to simulate typical indoor listening conditions. Each aricraft signal was superimposed on a controlled random traffic background signal having a duration exceeding that of the aircraft event. The primary conclusions reached in this investigation show that the presence of a steady mean traffic background noise can reduce the perceived noisiness of aircraft flyover events, provided that the judgment time available is sufficiently greater than the aircraft event time. For a given peak event level, a reduction in associated background noise of 21 dB(A) is shown to be equivalent subjectively to an increase of 5·5 dB(A) in peak event level, with fixed background conditions. Best linear data regressions were found with an index of the form L₀ + k(L_p ? L₀), where L_p and L₀ are the peak signal and mean background levels, respectively. Although the regressions obtained with the noise pollution index, L_NP, for single event judgments generally showed a lower correlation than the L₀ and (L_p ? L₀) regression variables the score data did show a number of significant trends which are also associated with the L_NP index variations computed for single noise events.     

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.     

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.