Abstract
The effects of aging on high-frequency hearing sensitivity and distortion product otoacoustic emissions (DPOAE) were investigated in 14 normal hearing persons aged 20-41 years. High-frequency hearing sensitivity was studied using the buzzing sound of a mosquito (sound A: 12.5kHz, sound B: 16kHz, sound C: 20kHz). DPOAE was recorded with an Otodynamic Analyzer ( ILO292-USB). The F2/F1 ratio was fixed at 1.2 and the DP level of 2F2- F1 was investigated at 9 points between 793 and 7,966Hz. The stimulus intensity of F1 and F2 was fixed at 70dBSPL.
Results: All 14 persons could hear sound A, but none heard sound C. Sound B was audible to 7 persons, but not to the other 7 persons. The hearing group was 10.9 years younger than the non-hearing group.
In regard to the DPOAE, the DP increased with from 5,042Hz to 6,348Hz in the hearing group. On the other hand, it decreased in the non-hearing group.
Our conclusion is that the cochlear dysfunction for high frequencies already begins in younger than 41 year old group before the age of 41 years and it was presented with hearing audibility and DPOAE.
