Sex Difference in Noise Susceptibility, especially in C⁵ dip Formation

Abstract

The threshold of hearing for pure tones were studied in a population in noise area around a air port compare with another population in control area in the suburbs of Fukuoka. An age stratified sample of subjects were drawn from both populations on a total 840 subjects deviled into decades from 20 to 60 years. Audiometric measurment at 500, 1000, 2000, 4000, and 8000Hz were made in three years repeatedly.
In both areas women have more sensitive hearing than men in high frequencies and this sex difference was especially demonstrable at 4000Hz in all decades. Therefore the audiograms of men showed a type of C⁵ dip and the one of women a typical high tone hearing loss of presbyacusis without a dip formation.
According to the results of statistical examination with t-test, the sex difference at 4000Hz in noise area were significant in all decades, although in control area insignificant in all decades.
To the causes of this sex difference at 4000Hz in both areas, the extrinsic factors such as firings in the second world war, occupational noise and direct head trauma, were attributed from the results of questionaire survey on the audiological characteristics.
The fact that the sex difference at 4000Hz was significant in noise ayes and insignificant in control area indicates that there might be a difference in noise susceptibility between women and men, especially a intrinsic difference in C⁵ dip formation.