Transient evoked otoacoustic emissions in patients with normal hearing andin patients with hearing loss

Objectives: 1) To evaluate transient evoked otoacoustic emission (TEOAE) te st performance when measurements are made under routine clinical conditions . 2) To evaluate TEOAE: test performance as a function of frequency and as a function of the magnitude of hearing loss. 3) To compare test performance using univariate and multivariate approaches to data analyses. 4) To provi de a means of interpreting clinical TEOAE measurements. Design: TEOAEs were measured in 452 ears of 246 patients. All measurements were made after acoustic immittance assessments, which were used to demonst rate that middle-ear function was normal at the time of the TEOAE: test. TE OAE amplitudes and signal to noise ratios (SNRs), analyzed into octave band s centered at 1, 2, and 4 kHz, were compared with the pure-tone threshold a t the same frequencies. Data were analyzed with clinical decision theory, c umulative distributions, discriminant analyses, and logistic regressions. Results: Using univariate analysis techniques, TEOAEs accurately identified auditory status at 2 and 4 kHz but were less accurate at 1 kHz. Test perfo rmance was best when audiometric thresholds between 20 and 30 dB HL were us ed as the criteria for normal hearing. TEOAE SNR resulted in better test pe rformance than did TEOAE amplitude alone; this effect decreased as frequenc y increased. Multivariate analysis methods resulted in better separation be tween normal and impaired ears than did univariate approaches, which relied on only TEOAE: amplitude or SNR when test frequency band and audiometric f requency were the same. This improvement in test performance was greatest a t 1 kHz, decreased as frequency increased, and was negligible at 4 kHz. Conclusions: TEOAEs can be used to identify hearing loss in children under routine clinical conditions. Univariate tests accurately identified auditor y status at mid and high frequencies but performed more poorly at lower fre quencies. The decrease in performance as frequency decreases may be a resul t of increased noise at lower frequencies but also may be due to properties of the measurement paradigm ("QuickScreen," high-pass filter at 0.8 kHz), which would not be ideal for recording energy around I kHz. The improvement in test performance when SNR was used and the interaction of this effect w ith frequency, however, would be consistent with the view that test perform ance in lower frequencies is at least partially influenced by the level of background noise. Multivariate analysis techniques improved test performanc e compared with the more traditional univariate approaches to data analysis . An approach is provided that allows one to assign measured TEOAE amplitud es, SNRs, or outputs from multivariate analyses to one of three categories: response properties consistent with normal hearing; results consistent wit h hearing loss; hearing status undetermined.