Comodulation masking release and monaural envelope correlation perception in listeners with cochlear hearing loss

This study investigated the comparative dependence of comodulation masking release (CMR) and monaural envelope correlation perception (MECP) on the degree of envelope similarity in pre-senescent adult listeners with normal hearing (NH) or mild-to-moderate cochlear hearing loss (CL). A 1600-Hz pure-tone signal was used to measure CMR as a function of degree of envelope correlation in 100-Hz-wide noise bands centered at 727, 1093, 1600, 2300, and 3268 Hz. The same noise band configuration was used to measure MECP thresholds for both comodulated and independent standards. Envelope correlation was adjusted by mixing comodulated and independent maskers at variable intensity ratios. The five-band complex was 85 dB SPL. Signal thresholds improved monotonically (i.e., CMR increased) with increasing degrees of envelope correlation for all listeners. Results for CL listeners were most similar to data from previous NH listeners at a 72 dB SPL masker level. For MECP, performance patterns for the two conditions were uniform across NH listeners, whereas those for CL listeners exhibited greater individual differences. Finally, CMR and MECP performance appeared to be related in listeners with CL. The pattern of results will be discussed in terms of the effects of CL on sensitivity to envelope similarity.