Forward masking recovery and peripheral compression in normal-hearing and cochlear-impaired ears

Iso-response temporal masking curves are obtained from normal-hearing subjects at a probe frequency of 1000 Hz for masker frequencies between 500 and 1200 Hz. Time constants calculated from the temporal masking curves varied with masker frequency, from around 70 ms for low off-frequency maskers (500–600 Hz) to around 36 ms for on-frequency maskers (close to the probe frequency). Continuing Bilger’s earlier pursuits of nonlinearities in hearing, estimates of peripheral compression were calculated under the assumption that the response to a low off-frequency masker is linear at the probe frequency place. Average compression exponents varied from close to 1.0 for remote off-frequency maskers (both below and above the probe) to below 0.4 for on-frequency maskers. Input–output transfer functions derived from the compression exponents were consistent with BM transfer functions recorded in animals with normal cochlear function. Comparisons of iso-response temporal masking curves in subjects with sizable cochlear hearing losses at the probe frequency yielded linear transfer functions consistent with BM data from cochlear-damaged animals. It is concluded that time constants for recovery from forward masking in ears with cochlear hearing loss are no different than those obtained from normal-hearing ears, once differences in peripheral compression are taken into account. [Work supported by NIH-NIDCD Grant DC00149 and the Lion’s 5M International Hearing Foundation.]