Noise-induced extraaural effects

Abstract

The paper presents roughly the state of the art concerning the extraaural effects of noise.Noise-related alterations comprize primary effects that occur during the period of noise exposure(e.g.speech interference, sleep disorders, altered autonomous functions), secondary effects that are mediated by the primary effects(annoyance, degraded well-being and performance), and tertiary effects, i.e.long-term health effects(hypertension, cardiovascular diseases).Where the causal relations between noise and acute primary effects are evident and very likely for cumulative responses and secondary effects, it was as yet impossible to determine causal relations between health disorders and noise exposure despite well founded hypotheses.The difficulties to determine causal relations increase with the time lag between the on-set of noise exposure and the manifestation of an effect in question.The reasons are manifold.Where the primary effects were almost exclusively studied in the well controlled experimental situation in the laboratory, the assumed health effects cannot be studied but in the field, where the acoustical situation varies considerably and where many other acoustical and non-acoustical environmental agents may enhance, attenuate or even mask the primary and secondary responses to the noise in question but might nevertheless—as non-specific stimuli—contribute to the genesis and manifestation of health effects.Another important factor is habituation, that causes a reduction of primary and secondary responses with time.The significance of these contributors in view of the hypothesized health effects must be elucidated in future studies.Other topics for future research are discussed as well.