1989 Fiscal Year Final Research Report Summary
Defense mechanism of the ear against loud impulsive noise
| Project/Area Number |
62480361
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Otorhinolaryngology
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| Research Institution | University of Occupational and Environmental Health, Japan |
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Principal Investigator |
HABU Hideaki University of Occupational and Environmental Health, Japan, 医学部(耳鼻咽喉科), 助手 (80189597)
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| Co-Investigator(Kenkyū-buntansha) |
OKAMOTO Ken The Second Tokyo National Hospital, Tokyo, 院長 (60122842)
FUJII Tetsuro University of Occupational and Environmental Health, Japan, 医学部(耳鼻咽喉科), 助手 (30189998)
TAKYU Hiroshi Tokai University, 医学部(医学情報部), 講師 (00188129)
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| Project Period (FY) |
1987 – 1989
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| Keywords | acoustic trauma / sound susceptibility / temporary threshold shift (TTS) / acoustic reflex (AR) / prediction / attention / contingent negative variation / anechoic chamber |
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| Research Abstract |
We investigate acoustic trauma in view of individual vulnerability, and indicate how to prevent from hearing impairment due to impulsive noise exposure, approaching the way of prediction of the individual sound susceptibility.
First, we review our 21 cases of acoustic trauma and make clear their clinical feature. Using paper caps fired in a starting pistol, of which acoustical characteristics was previously analyzed, experimental impulse noise exposure has performed under some conditions, such as shooting voluntarily, being shot without notice, neck torsion and so on. The results would be helpful to establish a safety standard of the exposure. Auditory brainstem response (ABR) threshold shifts of guinea pig, bred in an anechoic chamber for a long period,for impulsive noise exposure are measured. Some of them show less change than that of the control, but not significant. That offers a datum of causal connection between the state of ordinary noise exposure and the sound susceptibility.
Next, we examine whether the different way of paying attention makes the different degree of hearing impairment. Some are inclined to make more temporary threshold shifts (TTS) when they pick up syllables under a noisy background. Concentration was estimated by contingent negative variation (CNV) objectively. Amplitude of acoustic reflex (AAR) increase in some volunteers with a previous warning. Moreover, volunteers whose AAR increase gradually for rhythmic signals, have tendency to increase AAR provoked by a loud impulsive noise with prediction significantly.
Our research demonstrates the existence of such people as described above. The results suggest that central nervous system take some part in defense mechanism against impulsive noise exposure. Further study upon our products would be useful for prevention from acoustic trauma and prediction of the individual sound susceptibility.
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