Test-retest reliability of distortion product otoacoustic emissions in the 1 to 7 kHz range

Abstract

Distortion product otoacoustic emissions (DPOAEs) are regularly used to measure cochlear status in the high frequency range, as when monitoring ototoxic medication or for assessing noise-induced hearing loss. This study measured default DP-gram protocols and user-defined DP spectrum protocols in 35 normal hearing young adults using Otodynamics ILO96 equipment. Very short-term and short-term reliability was assessed, with measures conducted 20 minutes, and an average of 15 days later, respectively. The test resolution setting for the DP-gram measurements was varied between 1 to 8 points per octave in each test series. DPOAE amplitudes in the default frequency range (1 to 6 kHz) between test and short-term retest were highly correlated, with average r = 0.81. Standard error of measurement (SEM) was found to average 2.64 dB for DPOAE amplitude in the default frequency range. DPOAE amplitudes in the higher frequency range of 6.5 to 7 kHz were also significantly correlated between test and short-term retest; r ranged from 0.80 to 0.82 and SEM ranged from 2.59 to 3.04 dB. The various resolution and retest conditions showed no significant differences in reliability. DPOAE measurement in the 6.5 to 7 kHz range can be considered a reliable tool for monitoring cochlear function in cases such as exposure to ototoxic medication or noise. © 2005 Taylor & Francis.