Showing papers on "Impulse noise published in 1985"
TL;DR: This work has shown that classification of impulsiveness based on the sample kurtosis meets the requirements of a generally applicable impulse definition.
Abstract: Determining when a worksite exposure should be considered impulsive is a problem which has complicated both research into mechanisms of auditory pathology and protection of the exposed worker. An ideal solution requires that a definition of impulsive noise be developed which is independent of specific characteristics such as duration and amplitude. As an alternative to duration independence, a fixed time window over which a statistic is calculated may also serve as a basis for classification. Additionally, selecting this window on the basis of TTS production in the ear provides a biological basis for the definition of impulsiveness. Classification of impulsiveness based on the sample kurtosis meets the requirements of a generally applicable impulse definition.
51 citations
01 Mar 1985
TL;DR: In this article, the effects of aviation noise in many areas, ranging from human annoyance to impact on real estate values, are summarized, and current policies related to aviation noise are highlighted.
Abstract: : This report summarizes the effects of aviation noise in many areas, ranging from human annoyance to impact on real estate values. It also synthesizes the findings of literature on several topics. Included in the literature were many original studies carried out under FAA and other Federal funding over the past two decades. Efforts have been made to present the critical findings and conclusions of pertinent research, providing, when possible, a 'bottom line' conclusion, criterion or perspective. Issues related to aviation noise are highlighted, and current policy is presented. Specific topic addressed include: Annoyance; Hearing and hearing loss; Noise metrics; Human response to noise; Speech interference; Sleep interference; Non-auditory health effects of noise; Effects of noise on wild and domesticated animals; Low frequency acoustical energy; Impulsive noise; Time of day weightings; Noise contours; Land use compatibility; and Real estate values. This document is designed for a variety of users, from the individual completel unfamiliar with aviation noise to experts in the field. Keywords include: Helicopters; and Environmental impact.
27 citations
TL;DR: In the laboratory, four groups of 16 subjects rated the annoyance caused by three types of impulse sounds and by road-traffic sounds, all presented in background noise, and a correction term or penalty was derived, which gives the level of equally annoying traffic noise.
Abstract: In the laboratory, four groups of 16 subjects rated the annoyance caused by three types of impulse sounds (regular and irregular gunfire noise and metal‐construction noise) and by road‐traffic sounds, all presented in background noise. The subjects were presented with the sounds for 5‐min periods. The annoyance ratings were related to the A‐weighted equivalent level (Leq) of the sounds. From these annoyance ratings a correction term or penalty was derived, which, added to the Leq of the impulse sounds, gives the level of equally annoying traffic noise. The correction was determined for conditions in which (1) only the annoyance caused by specific sources, or (2) the annoyance caused by the total sound (specific source plus background) had to be rated. In addition, the indoor Leq of the constantly present background noise was 35 or 55 dB(A) by and large, the results showed that for lower levels of the sounds an impulse‐noise correction of at least 10 dB was required, whereas for higher levels the derived c...
19 citations
01 Oct 1985
TL;DR: A mathematical model of the auditory periphery has been developed and verified for sinusoidal stimulation using existing experimental data and it has been shown that the model can predict the potential auditory hazard from various impulsive stimuli, quantitatively in the guinea pig and qualitatively in man.
Abstract: It is widely accepted that for continuous noise, a relationship exists between the energy of sound (A-weighted) and its deleterious effects on hearing. However, when the exposure is to high intensity short duration impact or impulse noise, a hitherto unpredictable degree of damage can occur to the inner ear. The present study has set out to establish damage risk criteria for a variety of impulsive waveforms.A mathematical model of the auditory periphery has been developed and verified for sinusoidal stimulation using existing experimental data. Experimental results, obtained using guinea pigs under impulsive stimulation, were used to calibrate the model. Once calibrated the model was used to give information as to the damage likely to occur from other types of impulsive stimuli, hence reducing the need for extensive animal experimentation.It has been shown that the model can predict the potential auditory hazard from various impulsive stimuli, quantitatively in the guinea pig and qualitatively in man. Bot...
17 citations
TL;DR: The results indicate significantly increased blood pressure and water consumption with two weeks of noise exposure compared to shorter exposure durations.
15 citations
TL;DR: A simple algorithm, made up of the superposition of a median and an averaging filter, is presented and shown to be a promising candidate in the quest for fast and easy-to-implement processing routine.
Abstract: Statistical and deterministic properties of median filters are briefly discussed and their inherent advantages as a prospective tool in scintigraphic data processing are pointed out. The ability of median filters of suppressing impulse noise while the edge-like features of an image are preserved, is demonstrated on phantom data. The residual high-frequency noise remaining after median filtering can be subsequently reduced by standard smoothing procedures. A simple algorithm, made up of the superposition of a median and an averaging filter, is presented and shown to be a promising candidate in the quest for fast and easy-to-implement processing routine.
6 citations
01 Apr 1985
TL;DR: The VLSI implementation of two-dimensional generalized mean filtering for the removal of such impulse noises has been presented and the designed chip is capable of filtering each pixel inside the image within 14 clock cycles and is highly suitable for real-time application.
Abstract: In a black-and-white digitized image, pixels corrupted by impulse noise appear as either black dots or white dots. In this paper, the VLSI implementation of two-dimensional generalized mean filtering for the removal of such impulse noises has been presented. The designed chip is capable of filtering each pixel inside the image within 14 clock cycles and is highly suitable for real-time application.
2 citations
01 Jan 1985
TL;DR: In this article, a critical level above which loss mechanisms change from a mode that is probably metabolically based to one that is mechanically based was defined, and Stimulation at and above this second mode should be avoided.
Abstract: : To assess impulse noise hazard accurately, procedures should be based on the physiological mechanisms underlying hearing loss. Information from basic research studies is relevant in three areas. First, there is a spectrally dependent 'critical level above which loss mechanisms change from a mode that is probably metabolically based to one that is mechanically based. Stimulation at and above this second mode should be avoided. Second, in spite of the regulatory trend ignoring the time pattern of stimulation, studies continue to indicate at that intermittency ameliorates the effect of noise, producing less effect for a given amount of energy in the exposure. Lastly, a variety of sources can be interpreted as indicating that meters designed to rate hazard should have: a rise-time capability in the vicinity of 20 microseconds; a dynamic range of over 100 dB; and employ a frequency weighting function such as A-weighting, although the shape is not critical due to the relatively sharp tuning of the ear and the generally flat noise spectra commonly encountered in the work place. Keywords: Inpulse noise; Hearing loss; Dosimeter; Critical level; Noise hazard.
2 citations
01 Jun 1985
TL;DR: In this paper, the authors summarized 10 years of work by the U.S. Army Construction Engineering Research Laboratory (CERL) in the area of community response to impulsive noise and concluded that an energy type of model such as the C-weighted day/night average sound level (CDNL) is the best available descriptor for community response.
Abstract: : A major concern of Army planners is the trend toward siting off-installation housing and other noise-sensitive land uses in areas exposed to high noise levels produced by Army training or operational activities. To do effective noise-related assessments and planning the Army must be able to assess the community reaction to impulsive noise. Impulsive noise is produced by Army noise sources like armor, artillery, and demolition. This collection of papers summarizes 10 years of work by the U.S. Army Construction Engineering Research Laboratory (CERL) in the area of community response to impulsive noise. It is based on laboratory tests using a blast noise simulator, a study of Army-wide noise complaints, and attitudinal surveys conducted at Fort Bragg, NC, and Fort Lewis, WA. The attitudinal surveys provide most of the data. The major conclusions show that an energy type of model such as the C-weighted day/night average sound level (CDNL) is the best available descriptor for community response. Growth in annoyance to all noises increases monotonically with both sound amplitude and frequency of occurrence. This descriptor should incorporate a nighttime adjustment on the order of 10 decibels (dB). Keywords: Noise pollution; Communities; Fort Bragg, NC; and Fort Lewis, WA.
2 citations
TL;DR: The equal energy hypothesis (EEH) as discussed by the authors is based on the assumption that the hearing hazard associated with an impulse noise exposure is a monotonic function of the total A−weighted energy received by a listener.
Abstract: The equal energy hypothesis (EEH) for impulse noise is based on the assumption that the hearing hazard associated with an impulse noise exposure is a monotonic function of the total A‐weighted energy received by a listener. A series of experiments will be described in which the EEH was evaluated using exposure paradigms in which the repetition rate (4/s to 1 every 16 s) and the intensity (107‐ to 131‐dB peak SPL) of the impact noise were varied. Each of the various exposure paradigms had the same total energy. If the magnitude of the hearing loss is determined by the amount of acoustic energy, then all groups should develop the same amount of hearing loss. For equal intensities, the degree of damage increases with increased repetition rate. For example, the level of TTS increased approximately 25 dB when the repetition rate was increased from 1 every 16 s to 4/s. The effect of increasing the repetition rate also resulted in greater PTS and cochlear damage. The results are discussed in terms of the EEH and its appropriateness to impulse/impact noise. [This work was supported by NIOSH‐R010H1152.]
1 citations
01 Jan 1985
TL;DR: In this paper, the amplitude augmentation of evoked responses can be considered as a sign of certain cortical facilitation induced by noise, which implies some temporary functional change in the sense of improving auditory discrimination.
Abstract: After exposure either to a steady intensive noise (white noise, repetitive clicks, or narrow band noise, all of 110 dB SPL and 15 minute duration) or to impulse noise (300 impulses of 150 dB peak SPL and 50 ms impulse duretion) amplitudes of the evoked potentials recorded from the primary auditory cortex of guinea pigs in response to frequency modulation of pure tones were found to be systematically augmented while the response thresholds (△Fm) markedly lowered for most carrier frequencies and in most conditions. For all threshold lowering cases, the averaged AFm shift was about 1/2 of their pre-exposure values, with some extreme examples where post-exposure △Fm could be as small as only 1/5 of the pre-exposure ones or even lower. Post-exposure amplitude augmentation of evoked responses can be considered as a sign of certain cortical facilitation induced by noise. Lowering of △Fm tends to suggest that such cortical facilitation implies some temporary functional change in the sense of improving auditory discrimination.
Patent•
20 Jul 1985
TL;DR: In this article, the authors proposed to absorb impulse noise by applying fadeout and fade-in to a signal before and after an erroneous signal in a digital signal demodulating circuit of a digital audio signal.
Abstract: PURPOSE:To absorb impulse noise by applying fade-out and fade-in to a signal before and after an erroneous signal in a digital signal demodulating circuit of a digital audio signal CONSTITUTION:A demodulate data 1a of a demodulation circuit 1 enters a delay circuit 2 and the data enters a bit shift circuit 10 as a data 2a with a delay of N-word A P-S shift circuit 3 is activated with a clock signal 9a and in case of fade-out, an output (inhibiting signal) 7a of an up-counter 7 goes to logical ''1'' for a duration period (p), and a shift clock SCK is inhibited by a gate circuit 9 An S-P shift circuit 4 receives each bit being the MSB or below, applies parallel conversion and outputs a corrected demodulation data 4a The corrected demodulation data 4a shifts right the signal 2a and decreases the amplitude so as to form the fade-out state Then when the signal is applied with N-word delay, the system is brought into the muting state The system enters the fade-in state during the muting state and restores to the normal state finally
TL;DR: In this paper, the improvement in performance of M-ary non-coherent frequency-shift-keying (NCFSK) signals transmitted through a Rayleigh-fading channel computed by additive impulsive reverberation noise was demonstrated via the error probability expression.
Abstract: The improvement in performance of M-ary noncoherent frequency-shift-keying (NCFSK) signals transmitted through a Rayleigh-fading channel computed by additive impulsive reverberation noise; a situation typically arising in active sonar, with diversity is demonstrated via the error probability expression. It is also shown that there is a limitation to diversity improvement.