[Evoked otoacoustic emissions in humans with normal hearing].

The aim of the study was to assess and compare click-evoked otoacoustic emissions (e-OAE) and distortion product otoacoustic emissions (DPOE) in normally hearing subjects. The study was conducted on 48 ears in adults (12 women and 12 men; the age ranging from 16 to 40 years). E-OAE and DPOE was present in all examined ears. The amplitude of e-OAE ranged from 3.4 to 23.5 dB SPL (mean 11.7 +/- 4.95 dB SPL). In women the mean amplitude was slightly higher than in men. Spectral analysis of e-OAE revealed the highest level of otoacoustic emissions at the frequency 1000 Hz and significant decrease e-OAE at frequencies above 4500 Hz. DPOE were registered within the range of frequencies from 700 to 6000 Hz. Thus, DPOE allowed to measure otoacoustic emissions additionally in the high frequency region. We found significant variability in DPOE detection thresholds ranging from 25 to 70 dB SPL. Both types of otoacoustic emissions revealed significant inter-subject variability and very good test-retest repeatability. We conclude that both measurements allow to assess the function of the cochlea in the frequency specific regions, but DPOE, because of using pure tones stimuli, is more specific. The reference-values for adults are presented in this study.