Characteristics of transient evoked otoacoustic emissions in normal-hearing and hearing-impaired children

Objective: Transient evoked otoacoustic emissions (TEOAEs) were measured in children with normal hearing and in children with hearing loss to investig ate the characteristics of TEOAEs as they relate to overall amplitude and a mplitude spectra of evoking stimuli, and to audiometric status. Design: Three parameters of response measure (signal to noise ratio, amplit ude and reproducibility) were assessed to determine accuracy of identificat ion of varying degrees of hearing loss for broadband clicks, frequency-spec ific click bands and tone bursts. Forty-four children (66 ears) between 4 a nd 13 yr of age were evaluated for participation in the study. Fifty-nine e ars with intact tympanic membranes were included in the final analyses: 14 ears with normal hearing and 45 ears with hearing loss. Results: Children with normal hearing had robust responses that displayed n onlinear growth functions for broadband clicks and for tone bursts. Childre n with hearing loss had responses that decreased rapidly with decreasing st imulus level, if emissions were present at all. Data were analyzed using cl inical decision analysis and receiver operator characteristic curves. Broad band clicks presented at 80 and 86 dB peSPL identified a hearing loss great er than or equal to 30 dB HL with a high degree of accuracy. Click. respons es filtered into octave bands centered at 500 and 1000 Hz did not improve c lassification of hearing loss, in fact, the 500 Hz band was particularly in accurate. Results for click responses filtered into half-octave bands cente red at 2000 and 4000 Hz were comparable with those for the broadband click, although the 2000 Hz band was superior for identification of hearing loss greater than or equal to 20 dB HL for an 80 dB peSPL click, and greater tha n or equal to 30 dB HL for an 86 dB peSPL click. Results for tone bursts ce ntered at 500, 1000, 2000 and 4000 Hz, presented at 80 dB peSPL, were simil ar to results of the filtered click bands. Accuracy for identifying hearing loss increased with increasing center frequency. The 2000 and 4000 Hz tone bursts provided the best separation between normal-hearing and hearing-imp aired ears, with 4000 Hz being slightly better. Conclusions: Data from this study suggest that TEOAEs in children can separ ate ears with normal hearing from those with hearing loss using a variety o f stimulus and response conditions. Moreover, by using multiple stimulus le vels it may be possible to distinguish between mild and moderate hearing lo sses.