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Nov 1990

Volume 88, Issue S1, pp. S1-S200

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back to top Session 3BV. Bioresponse to Vibration: Noise‐Induced Hearing Loss in Persons Exposed to Vibration or Other Stimuli
Invited Papers
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Hand‐arm vibration syndrome and hearing loss in hard rock miners (A)

P. L. Pelmear

J. Acoust. Soc. Am. Volume 88, Issue S1, pp. S35-S36 (1990); (2 pages)

Online Publication Date: 14 Aug 2005

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Heating loss in forestry workers from hand‐arm vibration exposure has been reported in several studies. To evaluate this association further, a hand‐arm vibration survey of hard rock miners in five mines in Ontario included the collection of audiometric data. Both air conduction and impedance audiometry were used. The presence and severity of hand‐arm vibration syndrome were assessed by an occupational history and clinical tests. The hearing levels of both ears were combined, and by multiple regression analysis it was determined that there was a significant association between hearing level (at 4 kHz) and stage of hand‐arm vibration syndrome; hearing loss and age; and hearing loss and vibration exposure years. The hearing loss was significantly greater in miners with Raynaud's phenomenon who had less than 11‐years hand‐arm vibration exposure. The mechanism is still uncertain but it would seem that the accelerated hair cell destruction in such patients occurs because of reflex vasospasm of cochlea vasculature through the autonomic system.
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Changes in TTS2 values and tinnitus sensations due to complex exposure conditions among different human age groups (A)

Olavi J. Manninen

J. Acoust. Soc. Am. Volume 88, Issue S1, pp. S36-S36 (1990); (1 page)

Online Publication Date: 14 Aug 2005

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The study took place in an exposure chamber as a factorial experiment yielding a total of 48 exposure combinations, with 192 healthy, nonsmoking, male volunteers who were under 25 yr, 26‐39 yr, and over 40 yr old participating. The noise categories were (1) no extra noise and (2) stable 90‐dBA broadband noise. The vibration conditions included (1) no vibration and (2) whole‐body vibration with a frequency range of 2.8–11.2 Hz (along Z axis). The classes of physical work loads were (1) work at 2 W and (2) work at 7 W. The mental work was (1) no competition and (2) competition on least errors in mental arithmetic. All experiments were carried out at 35 °C. The TTS2 values were determined in both ears at 4 and 6 kHz. Tinnitus sensations were obtained through a five‐point rating scale. Results showed that noise, vibration, and physically loading work and their corresponding combinations influenced TTS2 values and tinnitus sensations most markedly. On the other hand, the combined effects of noise and vibration on TTS2 values were age‐dependent. In general, changes in tinnitus sensations seemed to be associated with the changes in hearing thresholds; the greater the TTS2 values, the greater were the means of tinnitus rating scores. [Work supported by the Academy of Finland.]
back to top Session 3BV: Bioresponse to Vibration: Noise‐Induced Hearing Loss in Persons Exposed to Vibration or Other Stimuli
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Effects of frequency and acceleration of whole‐body vibration combined with ototraumatic noise (A)

Clyde D. Byrne and Don Henderson

J. Acoust. Soc. Am. Volume 88, Issue S1, pp. S36-S36 (1990); (1 page)

Online Publication Date: 14 Aug 2005

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The effects of simultaneous exposures to whole‐body vibration and steady‐state noise were observed for thresholds of hearing in chinchillas. Four groups of animals were exposed to one of the following conditions: (a) noise only (500 Hz centered octave band, 100 dB SPL); (b) vibration alone at body resonance (63–89 Hz, 0.1 grms, 1.0 grms); (c) noise + resonant vibration; and (d) noise + nonresonant vibration (14–20 Hz, 0.1 grms, 1.0 grms,). The exposures lasted 6 h per day over 20 consecutive days. No interaction was demonstrated with the combination of nonresonant vibration and noise, but small increases in TTS and PTS were observed when the resonant vibration was added to the noise. Increasing the acceleration from 0.1 grms to 1.0grms did not result in a corresponding increase in TTS. Thresholds in the group exposed only to vibration improved slightly.
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Interaction of noxes: Amelioration, summation, or synergism (A)

W. Dixon Ward

J. Acoust. Soc. Am. Volume 88, Issue S1, pp. S36-S36 (1990); (1 page)

Online Publication Date: 14 Aug 2005

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That two noxious agents A and B act synergistically cannot be stipulated merely because their combined effect is greater than the effect of either separately. Instead, it must be shown that the effect is greater than predicted by the exposure‐equivalent principle, which can be accomplished only if the rate of growth of effect with increasing exposure to at least one noxious agent (A, say) is known. In that ease, the value of exposure to A that would have produced the effect that was in fact produced by B can be calculated; adding this exposure equivalent and the actual exposure to A will give a total exposure to A whose effect can be predicted from the growth function. Only if the combined effect actually observed exceeds this value can synergism be claimed. This principle was applied in order to show that there is no synergism between steady 90‐dBA noise and impulse noise with a peak level of 139 dB SPL, which means that crest factor is not an important parameter in the assessment of hazard from noise exposure. [Work supported by NIH.]
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The development of interior noise and vibration criteria (A)

David G. Stephens, Jack D. Leatherwood, and Sherman A. Clevenson

J. Acoust. Soc. Am. Volume 88, Issue S1, pp. S36-S37 (1990); (2 pages)

Online Publication Date: 14 Aug 2005

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The NASA Langley Research Center has completed a comprehensive research program that resulted in the development of a generalized model for estimating passenger discomfort response to combined noise and vibration. This model accounts for multiple frequency and multiple axes of vibration as well as the interactive effects of combined noise and vibration. The model has the unique capability of transforming individual components of a noise/vibration environment into subjective comfort units and then combining these comfort units to produce a total index of passenger discomfort and useful subindices that typify passenger comfort within the environment. This paper presents an overview of the model development including the methodology employed, major elements of the model, model applications, and a brief description of a commercially available portable ride comfort meter based directly upon the model algorithms. Also discussed are potential criteria formats that account for the interactive effects of noise and vibration on human discomfort response.
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