Cochlear nonlinearity in normal-hearing subjects as inferred psychophysically and from distortion-product otoacoustic emissions.
The aim was to investigate the correlation between compression exponent, compression threshold, and cochlear gain for normal-hearing subjects as inferred from temporal masking curves (TMCs) and distortion-product otoacoustic emission (DPOAEs) input-output (I/O) curves. Care was given to reduce the influence of DPOAE fine structure on the DPOAE I/O curves. A high correlation between compression exponent estimates obtained with the two methods was found at 4 kHz but not at 0.5 and 1 kHz. One reason is that the DPOAE I/O curves show plateaus or notches that result in unexpectedly high compression estimates. Moderately high correlation was found between compression threshold estimates obtained with the two methods, although DPOAE-based values were around 7 dB lower than those based on TMCs. Both methods show that compression exponent and threshold are approximately constant across the frequency range from 0.5 to 4 kHz. Cochlear gain as estimated from TMCs was found to be approximately 16 dB greater at 4 than at 0.5 kHz. In conclusion, DPOAEs and TMCs may be used interchangeably to infer precise individual nonlinear cochlear characteristics at 4 kHz, but it remains unclear that the same applies to lower frequencies.
Johannesen
Peter T
PT
Unidad de Audicion Computacional y Psicoacustica, Instituto de Neurociencias de Castilla y Leon, Universidad de Salamanca, 37007 Salamanca, Spain.
Lopez-Poveda
Enrique A
EA
D000161:Acoustic Stimulation; D000328:Adult; D001309:Auditory Threshold; D003051:Cochlea / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D017711:Nonlinear Dynamics; D017084:Otoacoustic Emissions, Spontaneous; D010470:Perceptual Masking; D010898:Pitch Perception; D011571:Psychoacoustics; D013997:Time Factors; D055815:Young Adult