RELIABILITY OF TRANSIENT-EVOKED OTOACOUSTIC EMISSIONS

Objective: This investigation addressed four factors affecting transie nt-evoked otoacoustic emission (TEOAE) reliability: 1) The effect of e voking-stimulus level, 2) the effect of analyzing bandwidth, 3) the ef fect of slight-mild hearing loss, and 4) the effect of variability in the stimulus spectrum. Design: TEOAEs at 80, 74, 68, and 62 dB pSPL ev oking-stimulus levels were measured in 25 ears spanning a range of hea ring levels from normal to mild hearing loss for a minimum of 10 test sessions. Reliability was assessed for 1/6-, 1/3- 1/2-, and 1-octave a nalyzing bandwidths. Results: Evoking-stimulus level, hearing loss, an d center frequency did not significantly affect reliability. With decr easing analyzing bandwidth, reliability decreased. Intrasubject test-r etest standard deviations were 1.2 dB for a broadband analyzing bandwi dth and 1.4, 1.5, 1.6, and 1.8 dB for 1-, 1/2-, 1/3-, and 1/6-octave a nalyzing bandwidths, respectively. Stimulus variability within narrowe r bandwidths was of sufficient magnitude to influence test-retest reli ability, and attempts to correct for the variations in stimulus spectr um were unsuccessful. Slopes of the input-output functions differed ac ross frequencies, with shallower slopes at higher frequencies, Conclus ions: In general, TEOAE, amplitude is highly reliable. For those indiv iduals in this study who were more variable, the variability was at lo w frequencies or across the entire frequency spectrum. For clinical ap plications, the choice of analyzing bandwidth should be based on consi deration of both frequency specificity (where narrow analyzing bandwid ths are optimal) and reliability (where wide analyzing bandwidths are optimal).