Improved psychophysical methods to estimate peripheral gain and compression.

It is possible that previous psychophysical estimates of basilar membrane gain and compression using temporal masking curve (TMC) and additivity of forward masking (AFM) methods using long-duration maskers (>30 ms) could have been affected by activation of the medial olivocochlear reflex (MOCR) (Jennings et al. ; Plack and Arifianto ). In experiment 1, AFM and TMC methods were compared to a new fixed-duration masking curve (FDMC) method in which the combined masker and signal stimulus duration is fixed at 25 ms. Estimates of compression were found to be not significantly different for TMC, FDMC and AFM methods. Estimates of gain were similar for TMC and FDMC methods. Maximum compression was associated with a significantly lower input masker level using the FDMC compared to the TMC method. In experiment 2, the FDMC method was used to investigate the effect of efferent activation on gain and compression estimates by presenting a precursor sound prior to the combined masker-signal stimulus. Estimated gain decreased as precursor level increased, and increased as the silent interval between the precursor and combined masker-signal stimulus increased, consistent with a decay of the efferent response.