Hearing threshold levels for an otologically unscreened, non-occupationally noise-exposed population in Sweden.

The aim of this study was to investigate the hearing threshold levels (HTL) of an otologically unscreened population in Sweden. The results are compared to other studies of otologically unscreened populations, and a new mathematical model of hearing threshold levels as a function of age is presented. The subjects were males and females aged from 19 to 81 years, selected from the province of Ostergötland in Sweden. The test battery included otoscopy, tympanometry, pure-tone audiometry, and a questionnaire. Subjects exposed to occupational noise were excluded, and in total 603 persons were included in the analysis. The regression analysis resulted in different hyperbolic tangent functions with four parameters: HTL=A+B x tanh(C x age+D).