Compression estimates using behavioral and otoacoustic emission measures.
Cochlear compression in normal-hearing listeners was estimated at octave frequencies from 250 to 4000 Hz using a forward-masking paradigm. Temporal masking curves (TMCs) for a 10-dB SL signal were obtained with two maskers -- one equal in frequency to the signal and another an octave below the signal. The ratio of the slope of the off-frequency function to that of the mid-level portion of the on-frequency function was computed as an estimate of the amount of compression at each frequency. Compression was less frequency selective at low frequencies, so an average of the off-frequency slopes at high frequencies (1000, 2000, and 4000 Hz) was used in computing the ratio for each signal frequency. Results indicated strong compression (approximately 0.15-0.30) at all frequencies using the averaged off-frequency slopes, indicating little difference in compression across frequencies. Distortion product otoacoustic emission (DPOAE) input-output (I-O) functions were obtained for each subject at 1000, 2000, and 4000 Hz. The slopes of the DPOAE I-O functions and the psychophysical growth rates were similar to one another, reinforcing the assumption that the forward-masking procedure is providing an estimate of cochlear compression, at least at frequencies from 1000 to 4000 Hz.
Williams
Erica J
EJ
Psychoacoustics Laboratory, Department of Speech and Hearing Science, Arizona State University, P.O. Box 870102, Tempe, AZ 85287-0102, USA.
Bacon
Sid P
SP
D000158:Acoustic Impedance Tests; D000161:Acoustic Stimulation; D000328:Adult; D000704:Analysis of Variance; D001307:Auditory Perception / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology; D001489:Basilar Membrane / Q000502:physiology; D003051:Cochlea / Q000502:physiology*; D006198:Hair Cells, Auditory / Q000502:physiology; D006801:Humans; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D010470:Perceptual Masking / Q000502:physiology*; D011571:Psychoacoustics; D012044:Regression Analysis