Behavioral, computational, and electrophysiological measures of temporal envelope processing

Listening to speech in noisy environments poses significant challenges for individuals with hearing loss, potentially due to poor representation of the temporal envelope. We explored the peripheral and central roles of temporal envelope processing using a gaps-in-noise task, computational modeling of the auditory periphery, and electrophysiology. Three behavioral experiments were conducted, using a 3-alternative-forced-choice procedure and a 3-down-1-up adaptive tracking method to estimate gap thresholds. Experiments 1 and 2 tracked gap detection (in ms) for various signal bandwidths, masker bandwidths, signal-to-noise ratios (SNRs), and gap modulation depths. Experiment 3 fixed the gap duration and tracked gap modulation depth (in dB) at various SNRs. Results showed that poorer SNRs were associated with poorer gap thresholds in all three experiments. In experiment 2, increased masker bandwidths also led to poorer gap thresholds. Modeling these results indicated that gap thresholds in noise can be attributed to mostly peripheral processes; however, the results of experiment 2 were more consistent with central factors. Participants also completed a passive EEG task using a standard acoustic change complex paradigm. The present study provides a comprehensive assessment of peripheral and central factors associated with temporal envelope processing which may have implications for amplification strategies. [Work supported by NIH.]