The perceptual significance of the cochlear amplifier was evaluated by predicting level-discrimination performance based on stochastic auditory-nerve (AN) activity. Performance was calculated for three models of processing: the optimal all-information processor (based on discharge times), the optimal rate-place processor (based on discharge counts), and a monaural coincidence-based processor that uses a non-optimal combination of rate and temporal information. An analytical AN model included compressive magnitude and level-dependent-phase responses associated with the cochlear amplifier, and high-, medium-, and low-spontaneous-rate (SR) fibers with characteristic frequencies (CFs) spanning the AN population. The relative contributions of nonlinear magnitude and nonlinear phase responses to level encoding were compared by using four versions of the model, which included and excluded the nonlinear gain and phase responses in all possible combinations. Nonlinear basilar-membrane (BM) phase responses are robustly encoded in near-CF AN fibers at low frequencies. Strongly compressive BM responses at high frequencies near CF interact with the high thresholds of low-SR AN fibers to produce large dynamic ranges. Coincidence performance based on a narrow range of AN CFs was robust across a wide dynamic range at both low and high frequencies, and matched human performance levels. Coincidence performance based on all CFs demonstrated the “near-miss” to Weber’s law at low frequencies and the high-frequency “mid-level bump.” Monaural coincidence detection is a physiologically realistic mechanism that is extremely general in that it can utilize AN information (average-rate, synchrony, and nonlinear-phase cues) from all SR groups.
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October 2001
October 01 2001
Rate and timing cues associated with the cochlear amplifier: Level discrimination based on monaural cross-frequency coincidence detection
Michael G. Heinz;
Michael G. Heinz
Speech and Hearing Sciences Program, Division of Health Sciences and Technology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
Hearing Research Center, Biomedical Engineering Department, Boston University, 44 Cummington Street, Boston, Massachusetts 02215
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H. Steven Colburn;
H. Steven Colburn
Hearing Research Center, Biomedical Engineering Department, Boston University, 44 Cummington Street, Boston, Massachusetts 02215
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Laurel H. Carney
Laurel H. Carney
Hearing Research Center, Biomedical Engineering Department, Boston University, 44 Cummington Street, Boston, Massachusetts 02215
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J. Acoust. Soc. Am. 110, 2065–2084 (2001)
Article history
Received:
September 01 2000
Accepted:
July 23 2001
Citation
Michael G. Heinz, H. Steven Colburn, Laurel H. Carney; Rate and timing cues associated with the cochlear amplifier: Level discrimination based on monaural cross-frequency coincidence detection. J. Acoust. Soc. Am. 1 October 2001; 110 (4): 2065–2084. https://doi.org/10.1121/1.1404977
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