Human perception of environmental noise in acute and chronic exposure conditions

摘要

Noise is unique among environmental pollutants as it effects are channeled through a normally functioning sensory system and that the effects are caused by reactions to the interpretation of the stimulus, rather than by an abnormal reaction in anaffected organ. Apart from occupational exposures and certain recreational exposures e g to rifle sounds, there is as of today little evidence of damaging effect on any organ in the body. Furthermore, the noise burden over a certain time cannot beestimated using a decrease in function of an organ or the presence of a biological marker of the exposure. For the risk evaluation process, this causes large difficulties in comparison to traditional toxicology.From a physiological point of view, experiments where acute episodes of noise are estimated with regards to their experienced disturbance, represent an incomplete concept. Under real life conditions, the exposure is repeated over a longer time and thenoise levels vary according to source characteristics and the environment such as climate and terrain. In the following, the relation between acute and real life exposure conditions will be examined with relation to habituation, the noise level, thenumber of events, and the characteristics of noise, exemplified by low frequency noise. The issue on individual sensitivity or attitudes will not been dealt with in this connection.