Effects of signal bandwidth and signal-to-noise ratio on noised-masked gap detection

Speech perception relies on our ability to process fast modulations in a signal. Such temporal processing often is probed using a temporal gap detection task. Because speech-in-noise listening is a common challenge for listeners with hearing loss, we investigated the role of the periphery to process temporal gaps in the presence of noise. Three experiments were conducted using a classic gap detection threshold method, including a 3-alternative-forced-choice procedure and a 3-down-1-up adaptive tracking method to estimate thresholds. Experiments 1 and 2 tracked gap detection (in ms) for various signal bandwidths, signal-to-noise ratios (SNRs), and masker modulation depths. Experiment 3 fixed the gap duration, then tracked gap modulation depth (in dB) at various SNRs. Experiments 1 to 3 showed similar effects of SNR, with poorer SNRs increasing gap thresholds. Masker bandwidth also reduced performance in Experiment 2. Current analyses with a common modulation filter bank frontend (Dau et al., 1997) performed on par as the normal hearing listeners suggesting that auditory gap detection and, by extension, temporal envelope processing, can be explained by peripheral processes. [Work supported by NIH R01 DC020514 and R01DC015051.]