Distortion-product emissions in humans with high-frequency sensorineural hearing loss

Abstract

Distortion-product emissions (DPEs) were detected in 20 adults with pure-tone behavioral threshold elevation at frequencies above 1000 Hz and in 20 adults with normal hearing. Equilevel pure tones at f1 and f2 (f2/f1 approximately 1.21) ranged from 65 to 20 dB SPL and were located at frequencies that approximated audiometric frequencies from 750 to 8000 Hz. DPEsat 2f1 − f2 ranged in amplitude from 23 to −18 dB SPL and were from 30 to 60 dB below the primaries for subjects with normal hearing. DPE amplitudes, response ranges, and slope values were significantly different between the two groups when the primaries were in the high-frequency region, but were similar at 0.75 and 1 kHz. DPEs were present for frequencies at which pure-tone behavioral thresholds were less than 15 dB HL and were absent or significantly attenuated if threshold exceeded 50 dB HL. The amplitude and range of DPE responses varied considerably when behavioral thresholds were between 20 and 45 dB HL. Results are compatible with similar findings from experimental animals.