Otoacoustic emissions for evaluating the low-frequency hearing of patients considered for partial deafness treatment.

Background: In the present study otoacoustic emissions (OAEs) were used to evaluate the hearing of partial deafness subjects who had normal hearing up to 0.5 kHz and severe hearing loss above that frequency. The purpose of the study was to detect OAEs at 0.5 kHz and determine whether broad-band or band-limited values of OAE parameters were better for distinguishing ears with OAEs from those without. Material and Methods: The study group consisted of 15 subjects with high-frequency hearing loss above 0.5 kHz. For reference, a group of 15 subjects with severe to profound sensorineural hearing loss over the whole of the 0.125DS8 kHz range was used. In both groups, click-evoked OAEs (CEOAEs) and tone burst-evoked OAEs (TBOAEs) of 1 or 0.5 kHz were evaluated using a reproducibility parameter, taking into consideration broad-band, octave, and half-octave band values. Results: In the study group the best results were obtained by using 0.5 kHz TBOAEs. Clicks and 1 kHz tone bursts generally did not produce a response at 0.5 kHz. TBOAEs at 0.5 kHz enabled the separation of partially deaf ears from ears with severe hearing impairment. Half-octave band filtering yielded the best results; however, it was only slightly better than broadband and octave band filtering. Conclusions: The results of the study indicate that the 0.5 kHz TBOAE is a better stimulus than CEOAE and 1 kHz TBOAE when cochlear function at low frequency needs to be tested. The half-octave band seems the best choice in order to get frequency- specific information. However the results should be treated with caution since the studied groups were relatively small. [ABSTRACT FROM AUTHOR]