CORRELATION FACTORS DESCRIBING PRIMARY AND SPATIAL SENSATIONS OF SOUND FIELDS

The theory of subjective preference of the sound field in a concert hall is established based on the model of human auditory-brain system. The model consists of the autocorrelation function (ACF) mechanism and the interaural crosscorrelation function (IACF) mechanism for signals arriving at two ear entrances, and the specialization of human cerebral hemispheres. This theory can be developed to describe primary sensations such as pitch or missing fundamental, loudness, timbre and, in addition, duration sensation which is introduced here as a fourth. These four primary sensations may be formulated by the temporal factors extracted from the ACF associated with the left hemisphere and, spatial sensations such as localization in the horizontal plane, apparent source width and subjective diffuseness are described by the spatial factors extracted from the IACF associated with the right hemisphere. Any important subjective responses of sound fields may be described by both temporal and spatial factors.     

Computer software for identification of noise source and automatic noise measurement

A new computational system for the environmental noise measurement and analysis has been developed. The system consists of binaural microphones, a laptop PC, and analysing software. A target noise is recorded automatically depending on the specified background noise level, and the acoustical parameters are calculated simultaneously. These functions allow for precise field measurements. The system is equipped with a template-matching algorithm for the identification of noise source. This function was implemented to avoid the effect of an interrupting sound such as voice and wind blowing during a measurement. Noise analyses in this system are based on the model of human auditory system. In addition to the time-series data of sound level, the important acoustical parameters of noise source are extracted from the running autocorrelation function (ACF) and the inter-aural cross-correlation function (IACF). It has been found that those parameters are strongly related to the auditory primary sensations and spatial sensations. Evaluation of the environmental noise based on these functions is another feature of this system. This paper describes the effectiveness of the ACF and the IACF analysis for analysing acoustical properties of noise and for evaluating the subjective response to noise.     

利用自相关函数和双耳自相关函数分析对交通噪声特征参量的提取~

对实地双通道测量获得的道路交通噪声和铁路噪声信号样本进行了自相关函数和双耳自相关函数(Interaural CrossCorrelation Function)的分析。进而通过对噪声样本时间因子和空间因子的相关性分析、主成分分析和主观评价实验,得到了3个铁路噪声源特征参量物理因子和4个道路交通噪声源特征参量物理因子。发现与传统的声压级测量相比,表征声音信号时间特性和空间特性的这7个物理量可以更全面、准确地表征交通噪声的特性。在对道路噪声进行测量或分析时,掌握与声源视觉宽度和音调感相对应的物理因子以及双耳时延和初始能量,就可获悉与人的主观评价相一致的道路交通噪声特征信息;对铁路噪声而言,掌握与声源视觉宽度相对应的物理因子以及双耳时延和声音的重复性特征,就可以得到与入主观评价相一致的铁路噪声特征信息。综合道路噪声特征参量和铁路噪声特征参量可以发现,双耳时延和与声源视觉宽度相对应的物理因子是与人的主观反应最为一致的主成分指标,说明噪声中决定人的评价的最主要的因素是代表空间特征的信号因子。      

Annoyance response to mixed transportation noise in Hong Kong

To better understand mixed transportation noise-annoyance response, a study was undertaken in Hong Kong to (1) unravel factors affecting annoyance response to mixed transportation noise; (2) contrast noise-annoyance relationships between road traffic and railway noise dominant situations; and (3) explain the differences, if any, between the two using structural equation modelling from the data collected in a social survey. Results of this study show that annoyance is largely determined by noise disturbance and perceived noisiness. Personal noise sensitivity, attitudes towards different means of transport and perceived quality of the living environment are secondary contributing factors. When road traffic noise dominates, annoyance is primarily determined by noise disturbance caused by the peaks of railway noise events; when railway noise dominates, peaks of train events can induce annoyance response directly without causing disturbance. Policy implications of such results on how to minimize noise-annoyance response are discussed in the paper.     

A new approach to assessing the performance of noise indices in buildings

The results of a wide acoustic environment survey are presented. Sound pressure measurements were carried out in a group of offices. These measurements lasted for five minutes and the resulting noise spectra were used to calculate the most significant acoustic parameters. During each measurement a questionnaire was administered to workers near each measuring position. The questionnaire asked them to indicate their subjective judgement about noise annoyance, noise loudness and dissatisfaction induced by noise present in the environment. The aim of the research was to investigate the performance of the measured noise indices in describing subjective responses to noise. A new method to calculate the average subjective responses is proposed. The performance of the noise indices was studied by means of linear regression analysis. Finally the A-weighted equivalent sound pressure level proved to be the best index among those analysed in describing subjective auditory sensations.     

Magnetoencephalographic responses correspond to individual annoyance of bandpass noise

The relation between human brain responses to an individual's annoyance of bandpass noise was investigated using magnetoencephalography (MEG) measurements and analysis by autocorrelation function (ACF) and cross-correlation function (CCF). Pure tone and bandpass noises with a centre frequency of 1000 Hz were used as source signals. The sound pressure level was constant at 74 dBA and the duration of the stimulus was 2.0 s. The scale values of annoyance for each subject were obtained by paired-comparison tests. In MEG measurements, the combination of a reference stimulus (pure tone) and test stimuli (bandpass noise) was alternately presented 30 times at a constant 2 s interstimulus interval. The results show that the effective duration of the ACF, τ_e, of MEG in the 8-13 Hz range, which represent repetitive features within the signal itself, became shorter during the presentation of an annoying stimulus. Also, the maximum value of the CCF, |φ(τ)|_max, became smaller. The shorter τ_e and smaller |φ(τ)|_max indicate that a wider area of the brain is unstable for longer with annoying auditory stimuli.     

Annoyance of noise stimuli in relation to the spatial factors extracted from the interaural cross-correlation function

While considering auditory-brain model for subjective responses, effects of spatial factors extracted from the interaural cross-correlation function (IACF) on annoyance of noise stimuli are examined. The previously developed indices to measure sound pressure levels (SPL) and frequency characteristics cannot fully explain the psychological effects of noise. In the first experiment, subjects judged their annoyance by changing fluctuations in the magnitude of interaural cross-correlation function (IACC) and the SPL. In the second, they judged their annoyance by changing fluctuations in the interaural time delay (τ_IACC) and the SPL. Results show that: (1) annoyance increased by increasing the fluctuations of IACC as well as the SPL, (2) annoyance increased by increasing the fluctuations of τ_IACC as well as the SPL.     

Subjective evaluation of work environment with special reference to noise

The presence of subjective noise annoyance was investigated among workers in a machine factory and a textile mill by using a questionnaire. The relation between annoyance due to noise and annoyance caused by other factors in the work environment was also investigated. The results show that annoyance due to noise exposure was common in both factories. Apart from the relation to the noise level, other acoustical characteristics, such as frequency spectrum and intensity, as well as differences between background and peak levels seem to determine the extent of annoyance. In the machine factory, the general satisfaction at work was significantly less among workers who had reported annoyance from noise, insufficient natural and artificial daylight and dust. In the textile mill noise and dust as well as monotonous work and fast working pace were of importance for the general satisfaction at work. Headache and tiredness were more common in the textile mill. The techniques used in the study could be applied to obtain further information on other industrial noise exposure criteria than hearing damage to serve as a basis for standards for annoyance.     

Implications of human performance and perception under tonal noise conditions on indoor noise criteria

This research investigated differences in task performance and perception under six non-time-varying ventilation-type background noise spectra with differing tonality. The results were related to five indoor noise criteria systems: noise criteria, balanced noise criteria, room criteria, room criteria mark II, and the A-weighted equivalent sound pressure level (L(Aeq)). These criteria systems are commonly used in the U.S. building industry, but concerns exist over whether they are appropriate for all noise situations. Thirty test subjects completed three types of performance tasks (typing, reasoning, and math) and answered questions about their perception of the indoor environment under each noise condition. Results showed that performance scores did not change significantly across the six noise conditions, but there were differences in subjective perception. For example, perception trends for tonality, annoyance, and distraction changed based on the frequency and prominence of discrete tones in noise. However, these perceptual changes were not fully reflected in the criteria level or spectral quality ratings. Additionally, task performance was related to subjective perception but not to criteria level predictions. As a result, the authors suggest that the current criteria should be modified to account for the frequency and prominence of tones in background noise.     

The effects of long-term exposure to railway and road traffic noise on subjective sleep disturbance

The exposure-response relationships between subjective annoyance with sleep disturbance from railway trains and road traffic noise were established from an extensive social survey by CENVR (Center for Environmental Noise and Vibration Research) in Korea. The objectives of this research are to determine the long-term effects of noise on sleep and to compare the exposure-response relationships from different noise sources with those from other studies and to elucidate the effects of some modifying factors on subjective responses to noise. From an investigation of the percentage of a highly sleep-disturbed population (%HSD) in response to railway and road traffic noise, it was found that sleep is affected more by railway noise than by road traffic noise. The effects of non-acoustical factors on the responses were examined and sensitivity was shown to be a significant modifying factor, as it pertains to subjective sleep disturbance. A comparison of the response curves from an analysis of pooled data from predominantly European surveys by Miedema and Vos [Behav. Sleep Med. 5, 1-20 (2007)] with the response curves from this survey showed more of a subjective sleep disturbance response in this survey to railway noise, whereas there was no significant difference in terms of a response to road traffic noise.     

Perception and annoyance due to wind turbine noise--a dose-response relationship

Installed global wind power increased by 26% during 2003, with U.S and Europe accounting for 90% of the cumulative capacity. Little is known about wind turbines' impact on people living in their vicinity. The aims of this study were to evaluate the prevalence of annoyance due to wind turbine noise and to study dose-response relationships. Interrelationships between noise annoyance and sound characteristics, as well as the influence of subjective variables such as attitude and noise sensitivity, were also assessed. A cross-sectional study was performed in Sweden in 2000. Responses were obtained through questionnaires (n = 351; response rate 68.4%), and doses were calculated as A-weighted sound pressure levels for each respondent. A statistically significant dose-response relationship was found, showing higher proportion of people reporting perception and annoyance than expected from the present dose-response relationships for transportation noise. The unexpected high proportion of annoyance could be due to visual interference, influencing noise annoyance, as well as the presence of intrusive sound characteristics. The respondents' attitude to the visual impact of wind turbines on the landscape scenery was found to influence noise annoyance.     

分光光度法研究钴(Ⅱ)-槲皮素配合物

利用分光光度法研究了槲皮素与Co（Ⅱ）形成配合物的最佳反应条件,测定了其配比和条件稳定常数。结果表明,在pH 4.7 HAc-NH₄Ac缓冲溶液中.槲皮素与Co（Ⅱ）配位,该配合物在584nm处有最大吸收。Co²⁺的浓度在2.0×10^-5—1.1×10^-4mol/L之间与吸光度呈线性关系。采用等摩尔连续变化法测得槲皮素-Co（Ⅱ）配合物的配位比为2:1,计算得到该配合物的条件稳定常数为2.7×10⁷L²·mol^-2。     

多噪声源共同作用下的总烦恼度评价与预测

主要研究了多噪声源共同作用下的混合噪声烦恼度的评价过程与预测方法. 首先, 设计并完成了固定播放时长噪声样本作用下的烦恼度主观评价实验, 获得了人工合成的混合噪声样本作用下的混合噪声烦恼度(亦称总烦恼度) α_T 评价数据与构成混合噪声样本的所有单一噪声样本单独作用时的烦恼度α_i (i=1, 2, 3, ···, K; K为混合噪声样本中单一噪声样本的总数) 评价数据. 随后, 细致分析了两组评价数据之间的关系, 提出在已知α_i 的基础上利用多元线性回归模型预测α_T. 最后, 解决了如何确定模型中对应各α_i的权值ω_i (i=1, 2, 3, ···, K) 的问题. 研究表明, 以所提出的权值确定方法建立的多元线性回归预测模型 能够较为成功地预测混合噪声样本作用下的总烦恼度评价值.     

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.     

Physiological aspects of noise-induced stress and annoyance

The relation between environmental noise exposure and physiological stress reactions is analysed, based upon the physiological characteristics of the hearing system. The potential of environmental noises to induce stress reactions is high and dependent how the noise is interpreted in the central nervous system. Occupational and environmental studies demonstrate that stress reactions occur and certain data suggest that medical effects such as increased blood pressure might result from prolonged noise exposure. As there is a relation between the extent of annoyance and stress, future research should define this on a dose-response basis using clinical as well as subjective exposure outcomes.     

主观评价实验中声音样本剂量值的度量方法

提出了一种基于对播放时长短时化处理的声音样本剂量值度量方法, 确定了十一种剂量值指标用于衡量具有固定播放时长声音样本的剂量值, 并分析了可能影响声音样本剂量值的主要因素; 随后, 对大量声音样本以各种指标度量的剂量值矩阵进行了聚类分析, 获得了三种类型的声音样本剂量值度量指标, 并确定了不同指标类型中的代表性指标; 最后, 分析了声音样本采用不同类型指标度量的剂量值与评价者对声音样本主观烦恼度等级之间的关系. 为利用主观评价实验进行固定播放时长声音样本作用下的主观烦恼度研究奠定了基础. 关键词： 声暴露量 烦恼度 声音样本 主观评价     

Adjustment on subjective annoyance of low frequency noise by adding additional sound

Structure-borne noise originating from a heat pump unit was selected to study the influence on subjective annoyance of low frequency noise (LFN) combined with additional sound. Paired comparison test was used for evaluating the subjective annoyance of LFN combined with different sound pressure levels (SPL) of pink noise, frequency-modulated pure tones (FM pure tones) and natural sounds. The results showed that, with pink noise of 250-1000 Hz combined with the original LFN, the subjective annoyance value (SAV) first dropped then rose with increasing SPL. When SPL of the pink noise was 15-25 dB, SAV was lower than that of the original LFN. With pink noise of frequency 250-20,000 Hz added to LFN, SAV increased linearly with increasing SPL. SAV and the psychoacoustic annoyance value (PAV) obtained by semi-theoretical formulas were well correlated. The determination coefficient (R²) was 0.966 and 0.881, respectively, when the frequency range of the pink noise was 250-1000 and 250-20,000 Hz. When FM pure tones with central frequencies of 500, 2000 and 8000 Hz, or natural sounds (including the sound of singing birds, flowing water, wind or ticking clock) were, respectively, added to the original sound, the SAV increased as the SPL of the added sound increased. However, when a FM pure tone of 15 dB with a central frequency of 2000 Hz and a modulation frequency of 10 Hz was added, the SAV was lower than that of the original LFN. With SPL and central frequency held invariable, the SAV declined primarily when modulation frequency increased. With SPL and modulation frequency held invariable, the SAV became lowest when the central frequency was 2000 Hz. This showed a preferable correlation between SAV and fluctuation extent of FM pure tones.     

环境噪声对儿童短时记忆力和注意力的影响

通过实验室研究探讨了不同噪声源在不同声压级条件下对儿童短时记忆力和注意力的影响。在每一个实验中都选取了30名710岁的儿童作为被试,在他们完成相应认知任务的同时,用耳机随机播放3565 dBA的交通噪声、白噪声和空调噪声,考察各种噪声条件对被试认知成绩和主观烦恼度的影响。研究结果表明,噪声对儿童的影响主要体现在主观烦恼度的变化上,不同的噪声条件并没有引起作业成绩的显著差异。影响儿童主观烦恼度的主要因素是声压级,随着声压级的增大,儿童的烦恼度会增加,当声压级在4550 dBA时,儿童对噪声开始产生烦恼感,当声压级在6065 dBA时,儿童对噪声产生了较显著的烦恼感。声压级对儿童烦恼度的影响没有随着噪声源的改变而改变。在相同的噪声条件下,短时记忆力实验中儿童的主观烦恼度都高于注意力实验,说明随着认知过程复杂程度的增加,噪声引起的烦恼度会相应增加。