Impulse noise

About: Impulse noise is a research topic. Over the lifetime, 4816 publications have been published within this topic receiving 63970 citations.

Noise, impulse noise, and other physical factors: combined effects on hearing.

Abstract: In most of the epidemiologic studies conducted during the last 20 years, impulse noise caused increased risk of hearing loss in comparison to continuous noise with the same acoustical energy. The interaction between noise exposure (broadband at 100 dB(A)) and hand-arm vibration (125 Hz at 2 ms-2 acceleration level) has been proven for people having vibration-induced white finger symptoms. This interaction is evidenced as a permanent hearing loss. However, why the interaction is seen only in people with VWF is not known. The mechanisms may be related to individual susceptibility, and hypotheses are given on the role of the autonomous nervous system regulating the peripheral vascular reaction. Whole-body vibration (2-10 Hz, at 10 ms-2 level) seems to increase the TTS when noise (broadband at 90 dB(A)) is present. This effect is more pronounced at higher temperatures. The hypothermia protects hearing against the effects of noise in animal studies. The interaction between noise and temperature decrease seems obvious in animal studies. Exercise has both increased and decreased the TTS during noise exposure. The effects have been successfully explained as the depression of the stapedius reflex. Thus, less protection against noise is provided for the inner ear in exercise conditions. The increase of the blood temperature also has been suggested to increase noise-induced TTS during exercise. Electromagnetic fields have been found to cause acoustical interactions in the inner ear. Animal studies and human studies have given contradictory results on the effects of magnetic coil devices on hearing. The MR imaging devices produce noise levels of 82-93 dB, which is not sufficient to produce the risk of permanent hearing loss when short exposure durations are taken into consideration. More systematic research is needed with accurately defined electromagnetic characteristics to reveal the potential interactions. The interactions seem to exist, but relatively high levels and durations of exposure are needed to produce an observable effect on hearing. More investigations are still needed on the permanent hearing loss in humans caused by simultaneous long-term exposures to interacting environmental factors.

Applicability of the Leq as a damage‐risk criterion: An animal experiment

Abstract: Within the European communities, the Leq8h is used as a damage‐risk criterion (DRC) for hearing protection. The use of such a DRC supposes that sound exposures with equal energy imply equal risk for noise‐induced hearing loss (NIHL). The aim of the present study, carried out with guinea pigs, was to test the applicability of the Leq8h for estimating the hazard of different noises having the same spectrum and acoustic energy. Therefore, only the temporal structure of noises was a variable (continuous, intermittent, or impulsive) and each noise had a Leq8h of 92 dB. The results indicate the Leq8h is not an accurate DRC. It overestimates the NIHL for intermittent and short‐continuous noises, whereas it seems to be useful for moderate‐intensity noises (95 dB) and for the impulse noise (101 dB). Furthermore, the data point out the notion of ‘‘critical intensity’’ which seems to play a determining role in the transition between metabolic and mechanical mechanisms involved in the acoustic trauma. Since the criti...

Exemplar-Based Denoising: A Unified Low-Rank Recovery Framework

Abstract: Exemplar-based image denoising algorithms have shown great potential for image restoration with a multitude of existing models. In this paper, we interpret nonlocal similar patch-based denoising as a problem of low-rank recovery. This offers a physically plausible model and unifies several existing techniques in a single low-rank recovery framework. The framework can handle complex noise models, such as zero-mean Gaussian noise, impulse noise, and any other noise that can be approximated by mixing these two kinds of noise. Moreover, we introduce a new nonconvex surrogate for the $l_{0}$ -norm and find the optimal solution of the optimization problems when the new norm is applied to low-rank recovery. The experimental results with different kinds of noise confirm the effectiveness of the proposed low-rank recovery framework and the new norm.

Microphone Array Analysis Methods Using Cross-Correlations

Abstract: Due to civilian noise complaints and damage claims, there is a need to establish an accurate record of impulse noise generated at military installations. Current noise monitoring systems are susceptible to false positive detection of impulse events due to wind noise. In order to analyze the characteristics of noise events, multiple channel data methods were investigated. A microphone array was used to collect four channel data of military impulse noise and wind noise. These data were then analyzed using cross-correlation functions to characterize the input waveforms. Four different analyses of microphone array data are presented. A new value, the min peak correlation coefficient, is defined as a measure of the likelihood that a given waveform originated from a correlated noise source. Using a sound source localization technique, the angle of incidence of the noise source can be calculated. A method was also developed to combine the four individual microphone channels into one. This method aimed to preserve the correlated part of the overall signal, while minimizing the effects of uncorrelated noise, such as wind. Lastly, a statistical method called the acoustic likelihood test is presented as a method of determining if a signal is correlated or not.Copyright © 2009 by ASME

Spectral interpolation coder for impulse noise cancellation over a binary symetric channel

Abstract: In this paper, a spectral interpolation coder (SIC) and decoder are investigated for simultaneous source coding and impulse noise cancellation. For simplicity of the analysis, we restrict ourselves to the framework of scalar quantization of a memoryless gaussian source to be transmitted over binary symmetric channel (BSC). Our approach is to make a carefully designed interpolation of the data in the spectral domain prior to quantization and transmission. The SIC decoder then exploits the properties of SIC codes in order to analyse, detect and correct (or reduce) erroneous data. A nice feature of this procedure is that the decoder deals simultaneously with the quantization noise and impulse channel noise; therefore it is able to reduce distortion introduced not only by the transmission channels errors but also by the quantizer. A comparaison study is also investigated in this paper: Simulations show that we obtain a 3dB improvement in SNR over the classical TSC scheme for a global rate of 8.2 transmitted bits per source sample and small BSC crossover probability.