Continuous judgment by category-ratio scaling of aircraft noise

A continuous judgment by category-ratio (CJCR) scaling method was used to evaluate the instantaneous annoyance of original and modified aircraft sounds. The result from the proposed method resulted in a temporal stream of annoyance levels for the whole flyover sequence that could be further analyzed. The test subjects were continuously rating their instantaneous annoyance on a Borg CR 100 scale® during the playback of 10 flyover sequences. Using a category-ratio (CR) scale instead of a category (C) scale, mathematical operations such as calculations of average were enabled but gave also advantages in terms of higher resolution in the responses. The results showed differences in perception in the time segment where the sound had been modified. The temporal stream of annoyance was also converted into overall judgments of the sounds, these estimations showed consistency with previous results obtained using the semantic differential and paired comparison method.     

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.     

Optimum reception of a signal with unknown duration against the background of white noise

An algorithm for optimum (Bayesian) detection and measurement of the duration of a rectangular pulse observed against the background of white Gaussian noise is developed. The potential characteristics of reception are obtained as a result of computer modeling of the synthesized algorithms. State University, Voronezh, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 12, pp. 1531–1541, December, 1997.     

Localization of brief sounds: effects of level and background noise

Listeners show systematic errors in vertical-plane localization of wide-band sounds when tested with brief-duration stimuli at high intensities, but long-duration sounds at any comfortable level do not produce such errors. Improvements in high-level sound localization associated with increased stimulus duration might result from temporal integration or from adaptation that might allow reliable processing of later portions of the stimulus. Free-field localization judgments were obtained for clicks and for 3- and 100-ms noise bursts presented at sensation levels from 30 to 55 dB. For the brief (clicks and 3-ms) stimuli, listeners showed compression of elevation judgments and increased rates and unusual patterns of front/back confusion at sensation levels higher than 40-45 dB. At lower sensation levels, brief sounds were localized accurately. The localization task was repeated using 3-ms noise burst targets in a background of spatially diffuse, wide-band noise intended to pre-adapt the system prior to the target onset. For high-level targets, the addition of background noise afforded mild release from the elevation compression effect. Finally, a train of identical, high-level, 3-ms bursts was found to be localized more accurately than a single burst. These results support the adaptation hypothesis.     

Effect of background levels on community responses to aircraft noise

The effect of variations in background noise levels on community reactions to aircraft noise has been investigated by using questionnaire and sound level data collected at a stratified random sample of residential sites in the vicinity of Toronto International Airport. The effects of variations in background noise (24 hour L_eq) on both individual and aggregate responses to aircraft noise have been examined. The response variables considered include annoyance, activity interference and complaints. The results of various statistical analyses show that the effect of background level is generally not significant. These findings are consistent with relevant findings from previous laboratory studies, but not with those from previous field studies.     

Underwater temporary threshold shift in pinnipeds: effects of noise level and duration

Behavioral psychophysical techniques were used to evaluate the residual effects of underwater noise on the hearing sensitivity of three pinnipeds: a California sea lion (Zalophus californianus), a harbor seal (Phoca vitulina), and a northern elephant seal (Mirounga angustirostris). Temporary threshold shift (TTS), defined as the difference between auditory thresholds obtained before and after noise exposure, was assessed. The subjects were exposed to octave-band noise centered at 2500 Hz at two sound pressure levels: 80 and 95 dB SL (re: auditory threshold at 2500 Hz). Noise exposure durations were 22, 25, and 50 min. Threshold shifts were assessed at 2500 and 3530 Hz. Mean threshold shifts ranged from 2.9-12.2 dB. Full recovery of auditory sensitivity occurred within 24 h of noise exposure. Control sequences, comprising sham noise exposures, did not result in significant mean threshold shifts for any subject. Threshold shift magnitudes increased with increasing noise sound exposure level (SEL) for two of the three subjects. The results underscore the importance of including sound exposure metrics (incorporating sound pressure level and exposure duration) in order to fully assess the effects of noise on marine mammal hearing.     

Traffic noise level as a guide for town-planning

The aim of this paper is to prove the validity of a mathematical model which gives the relationship between traffic noise level and traffic composition. This model was used at five different sites, representing different land uses, in Alexandria, Egypt.The paper gives various examples illustrating the fact that the equivalent noise level will be considerably reduced by changing the traffic composition. This shows that the town-planner can use various strategies to change the traffic composition in order to achieve quieter city environments.     

混沌噪声背景下微弱脉冲信号的检测及恢复

构建了一种在混沌噪声背景下检测并恢复微弱脉冲信号的模型.首先,基于混沌信号的短期可预测性及其对微小扰动的敏感性,对观测信号进行相空间重构、建立局域线性自回归模型进行单步预测,得到预测误差,并利用假设检验方法从预测误差中检测观测信号中是否含有微弱脉冲信号.然后,对微弱脉冲信号建立单点跳跃模型,并融合局域线性自回归模型,构成双局域线性(DLL)模型,以极小化DLL模型的均方预测误差为目标进行优化,采用向后拟合算法估计模型的参数,并最终恢复出混沌噪声背景下的微弱脉冲信号.仿真实验结果表明本文所建的模型能够有效地检测并恢复出混沌噪声背景中的微弱脉冲信号.     

Effects of background noise level on behavioral estimates of basilar-membrane compression

Hearing-impaired (HI) listeners often show poorer performance on psychoacoustic tasks than do normal-hearing (NH) listeners. Although some such deficits may reflect changes in suprathreshold sound processing, others may be due to stimulus audibility and the elevated absolute thresholds associated with hearing loss. Masking noise can be used to raise the thresholds of NH to equal the thresholds in quiet of HI listeners. However, such noise may have other effects, including changing peripheral response characteristics, such as the compressive input-output function of the basilar membrane in the normal cochlea. This study estimated compression behaviorally across a range of background noise levels in NH listeners at a 4 kHz signal frequency, using a growth of forward masking paradigm. For signals 5 dB or more above threshold in noise, no significant effect of broadband noise level was found on estimates of compression. This finding suggests that broadband noise does not significantly alter the compressive response of the basilar membrane to sounds that are presented well above their threshold in the noise. Similarities between the performance of HI listeners and NH listeners in threshold-equalizing noise are therefore unlikely to be due to a linearization of basilar-membrane responses to suprathreshold stimuli in the NH listeners.     

An acceptable exposure level for aircraft noise in residential communities

A review of existing guidelines and noise laws relating to aircraft indicated that they were governed, not by the acceptability of the aircraft noise to an exposed community, but by economic considerations. To examine the impact on aircraft noise requirements of a change in emphasis, from vehicle economy to noise acceptability, existing literature was used to estimate the maximum noise exposure from aircraft that a community would probably find acceptable. The suggested limit is 90 ± 5 PNdB for twenty noise events per day. Ideally, this noise level should fall within the airport boundary or on non-residential land.     

色噪声背景下微弱正弦信号的混沌检测

提出一种利用混沌在特定状态下对参数的敏感性来实现微弱正弦信号检测的新方案-该方案可以有效地将深陷在色噪声背景中的微弱正弦信号检测出来-给出了混沌检测的方法,分析了混沌检测中噪声对系统状态的影响-仿真实验表明该混沌检测系统对小信号非常敏感，对任何零均值色噪声均具有极强的抑制能力- 关键词： 微弱正弦信号 混沌检测 色噪声 信噪比     

Interferometric method of quasi-stationary signal isolation in a noise background

Scientific Research Radiophysical Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 10, pp. 1250–1257, October, 1989.     

Investigation of the trade-off effects of aircraft noise and number

This paper describes a laboratory study which investigated the trading relationship between aircraft noise level and number of events. The method developed for making judgments over periods of time and the experimental design, were such that data could be interpreted in terms of Scandinavian, UK and USA social survey results. Basic findings were that the form of the trading relationship was complex, and that more emphasis seemed to be placed on the number correction the higher the number of aircraft movements. Although cumulative noise indices such as L_eq (dB(A)) or NEF provide the best overall statistically significant central tendency measures, they tend to conceal the true nature of the number dependence. The form of this relationship could not be exactly quantified, as extension of the study to include lower rates of aircraft movement would be necessary.     

Temporal effects in simultaneous masking with on- and off-frequency noise maskers: effects of signal frequency and masker level

Temporal effects in simultaneous masking were measured as a function of masker level for an on-frequency broadband masker and an off-frequency narrow-band masker for signal frequencies of 750, 1730, and 4000 Hz. The on-frequency masker was 10 equivalent rectangular bandwidths (ERBs) wide and centered at the signal frequency; the off-frequency masker was 500 Hz wide and its lower frequency edge was 1.038 ERBs higher in frequency than the signal. The primary goal of the study was to determine whether previously observed differences regarding the effects of signal frequency and masker level on the temporal effect for these two different types of masker might be due to considerably different signal levels at threshold. Despite similar masked thresholds, the effects of signal frequency and masker level in the present study were different for the two masker types. The temporal effect was significant for the two highest frequencies and absent for the lowest frequency in the presence of the broadband masker, but was more or less independent of frequency for the narrow-band masker. The temporal effect increased but then decreased as a function of level for the broadband masker (at the two higher signal frequencies, where there was a temporal effect), but increased and reached an asymptote for the narrow-band masker. Despite the different effects of signal frequency and masker level, the temporal effects for both types of masker can be understood in terms of a basilar-membrane input-output function that becomes more linear during the course of masker stimulation.     

Awakening effects of simulated sonic booms and aircraft noise on men and women

In the course of several studies, 22 male and female subjects, ranging in age from 5–75 years, have been stimulated while asleep by simulated sonic booms (ranging in intensity from 0·6 to 5·0 lb/ft² (239·5 N/m²), as if measured out of doors at ground level) and by indoor recordings of subsonic jet flyover noise (ranging in intensity from 101 to 119 PNdB, as if measured out of doors). The summarized results of these studies suggest that (i) children (5–8 years of age) are uniformly unaffected by noise during sleep; (ii) older subjects are more sensitive to noise than younger subjects; (iii) women are more sensitive to noise during sleep than are men; (iv) within an age group, individuals may vary widely with respect to their relative sensitivities to noise during sleep; and (v) the frequency of behavioral awakening is a function of the intensity of both the simulated sonic booms and the subsonic jet flyover noise.     

Detection of an ultra-wideband quasi radio signal against background random noise

We perform synthesis and analysis of the maximum-likelihood detector of an ultra-wideband quasi radio signal whose duration may amount to several periods or even a fraction of a period of harmonic oscillation with unknown amplitude and phase. Characteristics of the classical quadrature detector on receipt of the ultra-wideband quasi radio signal are found. Applicability conditions of the model of a narrow-band radio signal for solving the detection problem to specified accuracy are formulated.     

Effects of level and background noise on interaural time difference discrimination for transposed stimuli

A method-of-adjustment procedure was used to measure thresholds for detecting a continuous sequence of brief 2-kHz tonal pulses in the presence of random-frequency masking sequences. Masker pulses consisted of either one or eight sinusoidal components and were either synchronous or asynchronous with the signal pulses. Effects of pulse rate and asynchronous gating were generally consistent with a reduction in informational masking due to segregation of the signal and masker streams. Despite use of continuous stimulus presentation to encourage stream segregation, masking was still obtained from most listeners in most conditions.