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 effect of a suppressor to environmental noise – A case study

The purpose of the study is to describe the effect of a suppressor to environmental noise with a typical Finnish rifle shooting range that has a shooting shelter and some noise berms. The noise measurements were carried out at Kyronpelto shooting range situated near Mikkeli in Finland. The range is equipped with wooden shooting shelter, the shooting distance is 150 m, and it has berms on sides and at the impact end. The terrain is relatively flat in the area. The best noise area reduction caused by a suppressor could be seen at angles of 315–45° from the shooting direction. The projectile noise dominates at angles 45–70°, and the effect of the suppressor is very small. To the side and back the shooting shelter has already gained significant noise attenuation, and therefore the suppressor cannot reduce the noise area much more. When there was a relatively tight shooting shelter to the side and back, the suppressor did not reduce the environmental noise area significantly any more. It can be calculated that the noise area of 65 dB (L_AImax) is reduced from 95 ha to 50 ha (0.95 km²–0.50 km²) with the help of a suppressor. However, most of the area is situated to the shooting sector and it has to be unoccupied for safety reasons.     

A methodology to study noise annoyance and to perform Action Plans follow up using as input an existing survey and noise map: Application to the city of Málaga (Spain)

The main purpose of this work is to establish a methodology which uses the advantages of stratified sampling to study noise perception. Taking as a starting point the results of an existing psychosocial survey of a large population sample, the proposed procedure consists in stratifying the original sample into homogeneous groups (clusters or classes) as far as noise perception/annoyance, and then select some representatives within each group. Those representatives will be used for further inquiries relating to noise annoyance perception (i.e. action plans follow up) and may facilitate further data acquisition making it faster and cheaper to acquire without significant precision loss.According to the European Directive 2002/49/EC, action plans for noise perception and noise level conflicts reduction shall be based both on existing noise maps and existing psychosocial surveys. It is in this context that the proposed methodology can be useful, since it will allow action plans follow up and thus evaluate in a fast and cost effective way the impact of action plans on the population.The methodology has been applied to the Málaga psychosocial survey results and the variability of estimates when working with subsamples (representatives from each group) has been studied. It is observed that performing a stratified sampling technique on the clusters optimizes the cost/precision ratio of estimators.     

Community noise survey of the city of Valdivia, Chile

A noise map of the city of Valdivia is created as a way to evaluate the noise of the city. This is a process that is usually associated with high operative costs. Some statistical techniques have been employed that have allowed the extrapolation of some measured values to assess noise at different times of the year, including “off” days thus reducing time and costs. The day-evening-night level L_DEN is used as the rating method to describe long-term annoyance. In conclusion, the noise pollution in the city is widespread throughout most of its streets area, where measured noise values are similar to those commonly observed in cities that do not have mitigation programs and whose road traffic is their principal noise generation source.     

Exposure-effect relationships between road traffic noise annoyance and noise cost valuations in Valladolid, Spain

Environmental noise can produce negative effects on people’s health since it interferes with basic activities such as sleeping, resting, studying and communicating. These effects depend not only on the physical characteristics of the noise itself, but also on parameters associated to each person and each environment. It is thus important to study noise pollution from a quantitative point of view as well as a from the point of view of the annoyance that it produces in the population.We have conducted a social survey aiming to identify the main sound sources, evaluate the annoyance and analyse the main effects of noise on people. The survey was distributed to a sample of people living approximately in the corners of an imaginary 250 m grid placed over the map of the city of Valladolid (Spain). The same corners were used to perform in situ measurements for a noise city map.There are two main purposes for this research work: (1) we want to compare the objective noise measurements to the annoyance reported by the people in order to find some kind of dose-effect relationship, and (2) we want to analyse how the population of Valladolid evaluates noise reduction from an economical and social point of view.     

Considering the influence of artificial environmental noise to study cough time-frequency features

In general the study of the cough mechanism and sound in both animal and human is performed by eliciting coughing in a reproducible way by nebulization of an irritating substance. Due to ventilation the controlled evaporation-protocol causes artificial noises from a mechanical origin. The resulting environmental low-frequency noises complicate cough time-frequency features. In order to optimize the study of the cough-sound the research described in this paper attempts on the one hand to characterize and model the environmental noises and on the other hand to evaluate the influence of the noise on the time-frequency representation for the intended cough sounds by comparing different de-noising approaches. Free field acoustic sound is continuously registered during citric acid cough-challenges on individual Belgian Landrace piglets and during respiratory infection experiments, with a duration of about 10 days, where room-ventilation was present.     

环境噪声学进展

本文简要地回顾了30年来中国环境噪声学的发展，并从飞机噪声、地面运输噪声、环境噪声影响与评价以及工业噪声控制四个方面介绍了近年来环境噪声学的进展。     

Experimental study of annoyance due to low frequency environmental noise

We have carried out a study of a particular environmental noise phenomenon which appears to be a cause of real and severe disturbance to certain people. The study has been based on field measurements and on laboratory studies and questioning involving two people who have suffered from this problem for some years. The disturbance is heard by them as a ‘throbbing’ sound and is particularly prevalent indoors, rather than out-of-doors.The study has indicated that the phenomenon arises with a broad band spectrum which lies close to the hearing threshold and which is unbalanced to the extent that the major stimulus occurs in the frequency range 20–100 Hz. It is suggested that the unbalanced spectrum may arise as a result of low frequency noise generated by distant industrial sources.     

Traffic noise in a high-rise city

Extensive results of traffic noise measured at 258 roadside sites in the high-rise city of Hong Kong are reported. From the results of this investigation the measurement sites can be very simply classified into three categories: enclosed, semi-enclosed and open. Distinct differences were found in the sound pressure levels L₁₀, L₅₀ and L₉₀ and in the standard deviations obtained at the enclosed site and at the semi-enclosed and open sites. Comparison with the results of similar measurements of traffic noise in other cities indicates that Hong Kong can be considered as the noisiest.     

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.     

An experimental study of jet noise part I: Turbulent mixing noise

The characteristics, both spectral and directivity, of turbulent mixing noise in the far field from subsonic and fully-expanded supersonic jet flows have been studied experimentally over an extensive envelope of jet operating conditions (jet exit velocity and temperature). The measurements were conducted in an anechoic room which provides a free-field environment. The results are presented in a systematic manner, and the observed trends and dependencies are discussed in detail. In particular, the changes in detailed jet noise features with varying velocity and exhaust temperature are assessed independently. Empirical prediction schemes or comparisons with recent theoretical investigations are not attempted here. However, the isothermal jet noise results are compared with those predicted by the freely-convecting quadrupole theories (that is, in the absence of any mean flow shrouding effects). The discrepancies between this model and the measurements, many of which have been recently shown to occur due to the presence of mean velocity and temperature gradients surrounding the sources, are obtained accurately over all jet operating conditions of interest.     

An experimental study of jet noise part II: Shock associated noise

The characteristics of the sound field of shock-containing under-expanded jet flows are studied by measuring the noise from a convergent nozzle operated over an extensive envelope of supercritical jet operating conditions. The measurements were conducted in an anechoic facility. They are complementary to the turbulent mixing noise experiments (described in Part I) for subsonic and fully-expanded (shock-free) supersonic jets. The overall results from shock-containing jets are compared directly with the corresponding results from shock-free jets, and the effects of nozzle pressure ratio and jet exhaust temperature on broadband shock-associated noise are assessed independently. For a supersonic jet, the regimes of jet operating conditions, observer angles, and frequencies over which the sound field is dominated by shock-associated noise are identified. Finally, the spectral results are compared in a preliminary manner with the spectra predicted by an existing theoretical model, and good agreement is obtained in most cases.     

An experimental study of the natural noise in the Transit-M hypersonic wind tunnel

Tests were performed at Mach number M = 6. Observations of flow pulsations were performed with the help of high-frequency measurements of pressure and heat fluxes and with the help of hot-wire anemometry. Measurements were carried out in a broad range of Re₁ numbers at various orientations and locations of sensors with respect to the nozzle exit plane. It is shown that the Transit-M noise varies weakly over the longitudinal coordinate, whereas on moving along the radial coordinate, some increase of the fluctuation level is observed due to approaching the mixing layer. Also, the distribution of axial asymmetry of the noise level was obtained.     

Noise impact assessment by utilizing noise map and GIS: A case study in the city of Chungju, Republic of Korea

In this study, a scheme to develop a noise map and noise impact assessment method using GIS has been suggested. After developing a road-traffic noise map for the city of Chungju, Republic of Korea, noise impact assessment was performed through analyzing the map. A 3-dimensional terrain model was generated using digital maps and building models were prepared using the information from draft and digital maps. To develop a noise evaluation model, a noise-source map for each road was generated. The noise levels at 25 locations close to roads were measured and compared with the expected noise levels to verify the developed noise map. An excess noise map was generated by comparing the road-traffic noise map with a noise-standard map. Using the excess noise map, the areas exceeding environmental noise standards were effectively evaluated through a GIS space analysis. The 3-dimensional facade noise map was generated to calculate the number of people exposed to a certain noise level.     

An exploratory study into the prediction of low frequency traffic noise

An exploratory study whose main aim was to develop equations for the prediction of low frequency traffic noise scales (from traffic parameters) is described. Summaries of noise and traffic measurement procedures are documented and the results of data analysis presented.The equations developed are shown to be accurate, but will require development to cater for more variable site conditions. The equations also indicate the large contribution made to low frequency noise levels by heavy vehicles. The implication of this for ‘lorry nuisance’ is discussed. Broad-band scales are shown to be reasonable surrogates for most, but not all, narrow-band low frequency effects. A method for determining low frequency scales using simple instrumentation is described.This paper is the first of three based on work carried out with the assistance of the Greater London Council (Scientific Branch) and which deal with the prediction of low frequency traffic noise scales and their relevance to vibration disturbance, lorry nuisance and building vibration.     

Further analysis of traffic noise in a high-rise city

This Note presents the findings of a further analysis of the results of road traffic noise measurements made in a high-rise city. The means and standard deviations of the sound pressure levels within the industrial, commercial, commercial/residential and residential areas are only very marginally different from one another.     

城市居民对环境噪声群体性反应的研究

2006年3月-8月在天津市区以问卷调查方式就居民对环境噪声群体性反应进行了研究。问卷采用了国际噪声组织ICBEN(International Commission on Biological Effects of Noise)第6小组推荐使用的两个标准调查问题,同时在参与调查的居民区内18个测点进行了道路噪声暴露量的测量,建立了居民对道路噪声群体性反应关系曲线。在此基础上对居民现处的声环境及居民对噪声问题的态度和评价特点进行了分析:调查对象能清楚地认识到噪声对生活质量的影响,对所处的声环境均持否定的态度,特别是对工作和公共场所的声环境。调查对象认为道路噪声是现在和将来困扰他们的最主要的噪声源,对建筑施工噪声最反感。调查对象更看重私密空间的声质量,噪声的主观评价也随被干扰活动的重要程度不同而不同。