Effects of residual masker, spectral resolution, and low frequency cues on the perception of ideal binary-masked speech

Abstract

This study investigated the intelligibility of ideal binary-masked (IdBM) stimuli under conditions with limited spectral resolution. In experiment 1, we used different IdBM local thresholds, which retain different amounts of residual masker and target information in the IdBM-stimuli. The stimuli were presented to 30 normal hearing listeners. The results indicated that, with a 6- or 12-channel tone-vocoder, the presence of residual masker in the IdBM-stimuli limits the intelligibility scores, thus preventing IdBM processing from achieving an ideal segregation of target from masker. In experiment 2, we investigated whether introduction of low frequency target information to the tone-vocoded IdBM-stimuli improves the intelligibility scores. Twenty normal hearing listeners participated in this experiment. The results indicated that in contrast to target F0 cues, inclusion of low-pass filtered target information (cutoff = 300 Hz) helped listeners segregate the target from the masker, thus improving the intelligibility of the IdBM-stimuli. These results argue against F0 as a segregation cue in electroacoustic conditions and suggest that target F0 cues do not provide benefits beyond those provided by IdBM.