Inherent envelope fluctuations in forward masking: Effects of age and hearing loss

Forward masking is generally greater for Gaussian noise (GN) than for low-fluctuation noise (LFN) maskers for listeners with and without sensorineural hearing loss (SNHL). Because older age and SNHL may affect recovery from masker envelope fluctuations differently, the current study explored which of these two factors contributed more substantially to the persistence of GN disruption. GN disruption was measured using three masker-signal delays (25, 75, and 150 ms) for three adult participant groups: younger listeners with normal hearing (YNH), older participants with normal, or near-normal, hearing (ONH), and older participants with sensorineural hearing loss (OSNHL). The role of underlying mechanisms was tested using a computational model for midbrain neurons. The primary result suggests that older listeners with normal or near normal hearing may be more susceptible to the deleterious effects of masker-envelope fluctuations than younger listeners with normal hearing. Results from the computational model propose that there may be a larger influence of efferent feedback and saturation of inner hair cells on GN disruption than previously expected.