Distortion product otoacoustic emission and auditory brain stem response measures of pediatric sensorineural hearing loss with islands of normal sensitivity

Objective: To assess the accuracy of: 1) distortion product otoacoustic emission (DPOAE) measures for the identification of frequencies at which auditory sensitivity is normal or near normal; and 2) click and nonmasked tone burst-evoked auditory brain stem response (ABR) thresholds for behavioral threshold estimation for children with sensorineural hearing loss characterized by islands of normal sensitivity. Design: DPOAEs and ABRs were recorded from five hearing-impaired and eight normal-hearing pediatric ears. The accuracy with which DPOAEs permitted identification of frequencies at which elevated hearing thresholds were present was examined. ABR and pure-tone threshold differences for the impaired ears were calculated. Results: For three of the five hearing-impaired ears, significant impairments would have been missed based on click-evoked ABR thresholds. One of those hearing-impaired ears provided an essentially normal 500 Hz tone burst-evoked ABR threshold as well. Four of the hearing-impaired ears provided a 500 Hz tone burst-evoked ABR threshold within 10 dB of the respective pure-tone threshold. However, click-evoked ABR and 500 Hz tone burst-evoked ABR threshold data did not adequately delineate the hearing loss configuration for hearing aid frequency response selection. DPOAEs were present at three out of four frequencies from 1000 to 4000 Hz at which sensitivity was normal or near normal (less than or equal to 25 dB HL) and absent at 10 out of 11 frequencies at which sensitivity was impaired. The use of DPOAEs to identify frequencies at which sensitivity was normal and the use of tone burst ABR thresholds at frequencies where DPOAEs were absent provided a better estimate of these pure-tone audiograms than was provided by click-evoked and 500 Hz tone burst-evoked ABR thresholds.