[Intra- and intersubject variability of acoustically evoked otoacoustic emissions. II. Distortion product otoacoustic emissions].

BACKGROUND

Distortion product otoacoustic emissions (DPOAEs) are evoked by simultaneously stimulating the cochlea with two tones. The DPOAE with the highest amplitude (at the frequency 2f1-f2) is usually used for routine audiological evaluation. Any interpretation of DPOAEs in a clinical setting must consider their intra- and intersubject variability.

METHODS

DPOAE measurements were performed in 36 normally hearing adults in three weekly test sessions. Each ear was tested twice per session, and the results were statistically analyzed.

RESULTS

All test candidates had measurable DPOAEs. Statistically significant differences in absolute DPOAE amplitudes were neither found between two measurements at the same day, nor at weekly intervals, nor between right and left ear of the same candidate. Absolute DPOAE amplitudes in women were significantly higher in the 2-6 kHz range whereas they presented with significantly lower amplitudes below 2 kHz when compared to men.

CONCLUSIONS

The present results indicate that monitoring of the inner ear status can be reliably performed using DPOAE measurements. Change in DPOAE amplitudes effectively indicate changes in the cochlear function with high sensitivity. Compared to TEOAE measurements, DPOAEs offer a higher frequency resolution in a broader frequency band and thus more detailed information about the cochlear condition.