Permanent and Temporary Diesel Engine Noise Dips

Abstract

In a previous article,¹ the question was considered whether the temporary and the permanent dips which have come about as a result of the influence of the same noise show some degree of resemblance. The answer to this question is of importance in view of the problem of whether data obtained from experiments on temporary noise deafness are applicable to the problem of the origin of the irreversible noise dip. In audiogram material of many hundreds of soldiers, whose auditory organs had been regularly exposed for a shorter or longer time to the noise of light firearms, we found 288 permanent dip-shaped hearing losses between 30 and 109 db. Continuous audiograms were made, and the individual differences in the region of greatest hearing loss were determined. The average place of the dip maximum was 5.9 kcps, the lowest place being 3, and the highest, 8 kcps. We determined the