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.     

Pair-wise comparison experiment on subjective annoyance rating of noise samples with different frequency spectrums but same A-weighted level

A pair-wise comparison experiment on subjective annoyance rating of nine different noise samples is the focus of this paper. These noise samples collected from some associated facilities in urban residential areas are classified into three different types according to their frequency characteristics, and their A-weighted levels are equalized at 65 dBA. Based on the assessment of judging errors and statistical validity analysis of each testee’s evaluating matrix, invalid data are eliminated. The results show that the percentage of testees who chose noise samples containing more low frequency components had an obvious downside trend with the descending degree of annoyance from ‘the most annoyed’ to ‘the least annoyed’. The result indicates that noise which has low frequency characteristic is more annoying than noise of other frequencies when their A-weighted level are the same. Therefore, A-weighted level cannot scientifically assess noise annoyance which contains low frequency components mostly.     

Estimation of annoyance due to low level sound

The concept of sound character is introduced as a physical attribute responsible for any systematic differences in annoyance due to different sounds at the same A-weighted equivalent sound level. It is thought that this sound character is more important at low sound levels than at high ones. A pilot experiment with refrigerator sounds indicated a clear effect of sound character. In particular, sharp onsets were shown to worsen the character of such sounds.     

Relationship between Electroencephalogram variation and subjective annoyance under noise exposure

The relationship between Electroencephalogram (EEG) variation and subjective annoyance was investigated with 70 dBA white noise and pure tones at 160 Hz, 500 Hz and 4000 Hz being selected as exposed noise sources. The results indicate that when the duration of noise was less than 6 s, Average Power of Electroencephalogram (APEEG) varied irregularly. When the noise lasted for 5 min, the sum of the relative APEEG of θ wave and the relative APEEG of α wave increased with the subjective annoyance increasing under noise exposures. The maximum power of θ wave appeared in the frontal region, while the maximum power of α wave appeared in the occipital region. Up to the fifth minute after noise exposure, more than two APEEG maximums of θ wave appeared, and the time points of maximum occurrence shifted forwards slowly following the increase of exposed noise frequency. The interval between two time points of maximum occurrence was reduced with the increase of the exposed noise frequency.     

A criterion for predicting the annoyance due to higher level,low frequency noise

Annoyance due to low frequency noise is more qidespread than was at one time believed and case histories indicate that the annoyance is not predicted accurately by a dB(A) measurement. In this study the psychophysical magnitude estimation technique was used to determine if a predictor of low frequency noise annoyance, superior to the dB(A), could be found. Ten noise measures were considered and it was concluded tentatively that the dB(B) noise measure could be used to predict the annoyance due to levels of low frequency noise in the range 90–105 dB overall SPL.     

Study on the effect of sound duration on the annoyance of helicopter noise by applying a technique of time compression and expansion of sound signals

The number of helicopter operations has rapidly increased during the last 20 years in Japan. Helicopter noise sounds different from other aircraft; the waveform of the sound pressure is impulsive and the signal duration is relatively long. The Environmental Agency of Japan implemented new guidelines for evaluating noise exposure around small airports, including heliports, in 1990. This study was executed in connection with the development of provisional guidelines. Psychoacoustic experiments were carried out to identify an evaluation index for helicopter noise. In order to examine the effect of duration independently, we not only used original sound recordings, but also synthesized sound signals. The durations of these sound signals were time compressed or expanded without degrading the quality of the original sound recording. The test results show that the effect of duration is significant, and that the A-weighted sound exposure level is a better index than the maximum A-weighted sound pressure level for the evaluation of helicopter noise.     

Laboratory studies on traffic noise annoyance

A laboratory study was undertaken to investigate the relation between traffic noise and annoyance with special reference to the number of noisy events. Students were exposed to different noise conditions for 45 and 120 minutes whereafter their reactions were assessed using a questionnaire. The extent of annoyance was found to increase with augmenting L_Aq levels but only when the number of noisy events remained equal. At equal L_Aq levels an increased extent of annoyance was found when the number of noisy events increased from 1 to 15 per hour. The results point to certain limitations in the validity of the equal energy concept and to the usefulness of laboratory studies to investigate reactions to environmental noise.     

车辆噪声烦恼度的音色表达

烦恼度作为评价噪声对人影响的重要指标,受到广泛重视并获得应用。通过主观评价实验和数据统计分析,从音色角度对城市典型车辆噪声烦恼度进行建模并给予物理解释。研究发现:(1)车辆噪声烦恼度音色空间由四个维度构成;(2)利用多元线性回归方法给出的车辆噪声烦恼度模型与声样本烦恼度拟合较好;(3)烦恼度空间维度与特定频谱特性具有较高的相关性。研究结果为车辆噪声烦恼度建模及降噪设计提供了新的思路。     

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.     

Synthesis of social surveys on noise annoyance.

Since noise was first recognized as a serious environmental pollutant, a number of social surveys have been conducted in order to assess the magnitude of the problem and to develop suitable noise ratings, such that, from a measurement of certain physical characteristics of community noise, one could reliably predict the community's subjective response to the noise. Recently, the author has reviewed the data from social surveys concerning the noise of aircraft, street traffic, expressway traffic, and railroads. Going back to the original published data, the various survey noise ratings were translated to day-night average sound level, and an independent judgment was make, where choice was possible, as to which respondents should be counted as "highly annoyed." The results of 11 of these surveys show a remarkable consistency. It is proposed that the average of these curves is the best currently available relationship for predicting community annoyance due to transportation noise of all kinds.     

A path model of aircraft noise annoyance

This paper describes the development and testing of a path model of aircraft noise annoyance by using noise and social survey data collected in the vicinity of Toronto International Airport. Path analysis is used to estimate the direct and indirect effects of seventeen independent variables on individual annoyance. The results show that the strongest direct effects are for speech interference, attitudes toward aircraft operations, sleep interruption and personal sensitivity to noise. The strongest indirect effects are for aircraft L_eq(24) and sensitivity. Overall the model explains 41% of the variation in the annoyance reported by the 673 survey respondents. The findings both support and extend existing statements in the literature on the antecedents of annoyance.     

考虑噪声烦恼度的机场飞机噪声收费模型和应用研究

随着我国民航运输业的飞速发展,机场噪声影响问题日趋严重。通过向航空公司或旅客收取噪声费来进行治理,是民航发达国家的普遍做法,也是我国未来的发展方向。该文在国外机场飞机噪声收费模型的基础上,提出了基于飞机噪声特性、噪声烦恼度、噪声治理投入费用和资金回收周期等因素的机场噪声收费模型。模型将机场噪声治理费用通过合理的回收周期按一定比例分配到各年度,再根据飞机噪声特性、噪声烦恼度将每年噪声收费分配到每架次飞机(或每位旅客)。飞机噪声特性根据ACI的机场噪声分级R1～R8来确定,噪声烦恼度借助Mamdani模型构建。应用表明,该收费模型关键因素考虑全面,计算方法先进简洁,费率合理。对于噪声较高飞机,夜间起飞收费为1219.06元/架次,客均收费10.16元;对于噪声很低的飞机,昼间着陆收费为66.10元/架次,客均收费仅0.15元。费率确定符合国际民航组织倡导的以支定收原则,有助于形成航空公司/旅客减噪激励机制同时又不致抑制机场航空业务增长。     

Study of annoyance by traffic noise in Leuven (Belgium)

In order to prepare a large-scale research programme on annoyance by traffic noise in big cities—sponsored by the Belgian Ministry of Health—this preliminary survey was carried out.Comparisons are made between the results obtained and those of comparable surveys by other laboratories. Attempts are made to improve research methods and accuracy of measurement.     

An investigation on annoyance caused by road-vehicle noise based on the autocorrelation function

The objective of this study is to reveal the cause of noise annoyance based on its perceptual properties.The available physical factors extracted from the autocorrelation function （ACF） were used to explain the primary sensations and representative perceptual properties of road-vehicle noise.Two novel factors,EMD and ESM.used especially for measuring fluctuation and smoothness of the ACF envelope,were proposed.It should be pointed out that ifφ₁ was not the maximum value exceptφ（0）,bothφ_max andτ_max were suggested to be added.Three primary sensations -loudness,pitch,and timbre have been acquired by applying the principal component analysis to ACF factors extracted from 232 noise samples.From 10 subjects, annoyance scale values were investigated using the magnitude estimation approach under wellcontrolled experimental conditions.It is realized that there certainly exist elementary factors for every primary sensation.Different ACF characteristics can induce diverse dominant sensation, which would control or determine the perceptual properties of the noise.The variability of dominant sensation and the priority difference in primary sensations will bring out subjective annoyance.Moreover,the mixture of elementary factors would confuse the auditory features, and induce subjective annoyance.In other words,it is the chaos of perceptual properties that cause and affect noise annoyance.     

Parameters influencing low frequency impact sound transmission in dwellings

As sound and vibration fields in dwellings exhibit modal behaviour at frequencies below 200 Hz, a systematic investigation of measurement and prediction uncertainty associated with impact sound transmission at low frequencies must include the effects of: location of the impact, type of floor, edge conditions, floor and room dimensions, room absorption and position of the receiver. Experimentally validated analytical models, described in a companion paper, have been used in an extensive investigation of impact sound transmission through rectangular homogeneous concrete floors and floating floors. The models were used to describe the effect of modal coupling and then to perform parametric and statistical studies aimed to identify the main factors affecting low frequency impact sound transmission.     

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.     

The effects of low frequency noise on people—A review

During the fast few years, the existence of high levels of man-made low frequency noise (0–100 Hz), and in particular infrasonic noise, has been reported in many environments. An effort has been made over the last decade to discover whether such high levels of low frequency noise are significant. A review of the effects of low frequency noise indicates that the effects are similar to those of higher frequency noise, that noise in the 20–100 Hz range is much more significant than infrasound at similar sound pressure levels and that the possible danger due to infrasound has been much over-rated.     

Enhancing the low frequency sound absorption of a perforated panel by parallel-arranged extended tubes

This paper is concerned with the use of a perforated panel with extended tubes (PPET) to improve the sound absorption confined to low frequencies. In comparison with a micro-perforated panel (MPP), the sound absorption can be significantly improved by using the PPET at the expense of the bandwidth of the sound absorption. A particular configuration combining four parallel-arranged PPETs with different cavities is introduced to achieve a wider bandwidth of the sound absorption at low frequencies. The analysis is extended to the combination of three parallel-arranged PPETs and a MPP to further increase the bandwidth of the sound absorption. A theoretical model is described to predict the sound absorption coefficient and the simulated annealing method is introduced to the proposed absorbers, allowing optimization of the overall performance. The theory with experimental validations demonstrates that the proposed configurations offer a potential improvement of more than one octave in the bandwidth of the sound absorption at low frequencies.