Behavioral estimates of basilar-membrane input-output in normal-hearing listeners

To characterize human cochlear processing it would be beneficial to behaviorally estimate the basilar membrane (BM) input-output (I/O) function. In recent studies, forward masking has been used to estimate BM compression. In this study, a growth-of-forward-masking (GOM) paradigm (e.g., Oxenham and Plack, 1997) was extended to also estimate the knee point of the I/O function between linear and compressive processing.

If a low-level signal is masked by an on-frequency masker, such that the signal is processed linearly and the masker compressively according to the I/O function, then a steeper GOM function is expected than that obtained for a high-level signal where both masker and signal are processed compressively.

The knee point can be estimated at the input level where the GOM slope changes significantly. Data were collected from seven normal - hearing listeners. The method was found to provide estimates of the BM I/O function for a wider range of input levels than in previously suggested methods, due to the additional estimates of the knee points.