衝撃騒音がモルモット内耳に及ぼす電気生理学的影響について

概要

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The damage-risk criterion (DRC) for hearing (ISO R 1999) supposes that sound exposure with equal energy implies equal risk for noise-induced hearing loss (NIHL). The purpose of this study, exposed to impact tone was to test the adequacy of Leq_<24h> for estimating the changes in electrophysiological data namely, cochlear microphonics (CM) compound action potential (CAP), endocochlear potential (EP) and the change in K^+ ion concentration in the scala media. The temporal pattern of tone was 1pulse/1sec or 1pulse/3sec and each tone had a Leq_<24h>=90, 85 and 80dB. The results are the following. Both steady state and impact tone exposure cause change of electrophysiological data. First, CM maximum output voltage after exposure to impact tone of 115dB (Leq_<24h>=90dB) was lower than after exposure to a 8kHz steady state tone of 90dB. CAP threshold (below 10uV) obtained after the 115 and 110dB exposure of impact tone were 5-10dB higher than that of steady state tone of 90dB. The negative EP induced by impact tone exposures showed the same tendency as the CM experiments. Having more frequent pulses (1pulse/1sec versus to 1pulse/3sec) means more inhibition. The K^+ concentration time course remained similar to the control when the Leq_<24h> was low (80dB).
北翔大学の論文