OTOACOUSTIC EMISSIONS AS AN OBJECTIVE MEANS FOR DIAGNOSIS AND GIVING EXPERT OPINIONS ON NOISE-INDUCED HEARING LOSSES

In order to assess occupational hearing loss, damage to outer hair cel l function must be demonstrated. Measurements of transiently evoked ot oacoustic emissions (TEOAE) and distortion products (DPOAE) allow clin icians to investigate objectively the cochlear amplification process. In this prospective study, 50 persons with suspected occupational hear ing losses were tested with pure-tone and speech audiometry. Additiona lly, TEOAE and DPAOE were determined. Significant linear correlations were observed when comparing hearing thresholds and speech discriminat ions with evoked emissions. Three groups were formed based on the OAE results: group A, TEOAE- and DPOAE-positive; group B, TEOAE-negative, DPOAE positive; group C, TEOAE- and DPOAE-negative. The groups were co mpared with regard to the weighted and simple discrimination scores an d percentage of hearing loss computed according to the Boenninghaus-Ro ser tables. Analysis of variance showed significant differences in hea ring losses among the three groups, allowing an objective statement to be made about the degree of work compromise: group A, <10%; group B, 10-15%; group C, greater than or equal to 20%.