Distortion product emissions and sensorineural hearing loss.

Distortion product emissions (DPEs) are intimately linked to normal outer hair cell function. Outer hair cell function is itself intimately linked with normal auditory thresholds. We sought to correlate frequency-specific DPE measurements with auditory thresholds, in seven frequency regions from 700 Hz to 6 kHz, in each of 21 ears. Eleven of these ears had thresholds below 25 dB SPL at every test frequency, whereas 10 ears demonstrated some degree of purely sensorineural hearing loss. An analysis of the correlation between DPE measurements and sensory thresholds suggests that DPE measures can predict frequency-specific auditory thresholds to within 10 dB over a range of sensory thresholds from 0 dB SPL to 60 dB SPL. Distortion product emissions promise to provide an objective, non-invasive measure of sensory thresholds. The clinical value of DPE measurement is enhanced by that fact that it is brief and requires minimal subject participation. A clinical test based on the DPE measurement will not displace conventional audiometry or auditory brain stem response measurement. It promises to provide new information about cochlear function to both the clinician and auditory physiologist.