Changwoo Lim

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.

The relationship between railway noise and community annoyance in Korea.

A study of community annoyance caused by exposures to railway noise was carried out in 18 areas along railway lines to accumulate social survey data and assess the relationship between railway noise levels and annoyance responses in Korea. Railway noise levels were measured with portable sound-level meters. Social surveys were administered to people living within 50 m of noise measurement sites. A questionnaire contained demographic factors, degree of noise annoyance, interference with daily activities, and health-related symptoms. The question relating to noise annoyance was answered on an 11-point numerical scale. The randomly selected respondents, who were aged between 18 to 70 years of age, completed the questionnaire independently. In total, 726 respondents participated in social surveys. Taking into consideration the urban structure and layout of the residential areas of Korea, Japan, and Europe, one can assume that the annoyance responses caused by the railway noise in this study will be similar to those found in Japan, which are considerably more severe than those found in European countries. This study showed that one of the most important factors contributing to the difference in the annoyance responses between Korea and Europe is the distance between railways and houses.

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.

Noise-induced annoyance from transportation noise: Short-term responses to a single noise source in a laboratory

An experimental study was performed to compare the annoyances from civil-aircraft noise, military-aircraft noise, railway noise, and road-traffic noise. Two-way within-subjects designs were applied in this research. Fifty-two subjects, who were naive listeners, were given various stimuli with varying levels through a headphone in an anechoic chamber. Regardless of the frequency weighting network, even under the same average energy level, civil-aircraft noise was the most annoying, followed by military-aircraft noise, railway noise, and road-traffic noise. In particular, penalties in the time-averaged, A-weighted sound level (TAL) of about 8, 5, and 5 dB, respectively, were found in the civil-aircraft, military-aircraft, and railway noises. The reason could be clarified through the high-frequency component and the variability in the level. When people were exposed to sounds with the same maximum A-weighted level, a railway bonus of about 3 dB was found. However, transportation noise has been evaluated by the time-averaged A-weighted level in most countries. Therefore, in the present situation, the railway bonus is not acceptable for railway vehicles with diesel-electric engines.

The influence of binaural effects on annoyance for transportation noise

A laboratory study was conducted to identify the significance of the binaural effect on annoyance by transportation noise. There were 377 participants (240 male and 137 female). Every participant marked the annoyance score (from 0 to 10) for each stimulus on their questionnaire. All of data were divided into four groups according to four types of transportation noise sources. The difference in the mean annoyance scores between subgroups according to sound recording/ playback techniques was statistically significant in the four noise groups. Stepwise multiple regression analysis was conducted. Using a regression model, predictions of L Aeq , Technique and their interaction term (L Aeq *Technique) involving dummy variable were made. In spite of some limitations of the process of the laboratory test, meaningful results were acquired. This study showed that the binaural effect was one of the acoustical factors modifying annoyance, and quantitative expression of binaural effect is suggested. Annoyance was explained by L Aeq and an interaction term in the resultant model functions for the four noise sources. Regression coefficients of the interaction term for each model equation were almost the same, which explained the extent of the binaural effect. The binaural effect was defined as the difference of annoyance variations between two sub-groups when L Aeq varies by ΔL Aeq from the specified noise level. The binaural effect was expressed as 0.01ΔL Aeq on the basis of a 0 to 10 annoyance scale.

Comparison of Human Responses to Transportation Noise in Monaural and Binaural Hearing, Part II: Annoyance

This paper continues companion paper, part I : measurement and analysis. As shown in companion Paper, information and energy in monaural signal is quite different from that of binaural signal. In this paper, difference between monaural and binaural signal of transportation noise are investigated in subjective response test. We executed hearing screening test before giving a subject response test and excluded subjects who had physical hearing loss. An annoyance response test was conducted using headphone to avoid cross-talk effect in binaural testing. Percentage of highly annoyed under binaural signal reproduction is higher than percentage of highly annoyed under monaural signal reproduction. Result implies binaural reproduction technique is proper for a study of human response to short-term noise exposure in a headphone simulated-environment.

Comparison of Human Responses to Transportation Noise in Monaural and Binaural Hearing, Part I: Measurement and Analysis

Measurement of noise is not only to know the information of acoustic pressure but to assess human response to noise. To find human response to transportation noise through the laboratory study we have to measure and reproduce noise. The method of noise reproduction is largely divided into monaural and binaural techniques. But human fundamentally hears sound through both ears, referred as binaural hearing. Binaural signal is different from monaural signal because it includes more information of physical phenomena like acoustical reflection, diffraction and refraction. Especially head and pinna play an important role in perceiving change of signal origin. So, the amplitude of binaural signal is higher than that of monaural signal and spectrum of both signals is discriminated. Most of assessment and regulation of transportation noise are, however, based on monaural measurement techniques. The quantitative difference between monaural and binaural measurement is investigated in this study. Comparison on several transportation noisesshows defect of information in monaural measurements.