Intelligibility of interrupted and checkerboard speech stimuli with two talkers: The effects of signal-to-noise ratios

Segregating target speech in a multi-talker background requires organizing speech fragments into a coherent stream of speech. The current investigation explored the intelligibility of temporally interrupted and checkerboard (interrupted in time and frequency) speech stimuli with one and two talkers. An experiment with one-talker stimuli revealed that the intelligibility of interrupted speech became lowest at a 255-ms segment duration. In contrast, for two- and four-band checkerboard speech, the minimum intelligibility occurred at around 113–160-ms segment durations. Furthermore, a series of experiments with two-talker stimuli revealed that no phonemic restoration was found, and that signal-to-noise ratios (SNRs) between target and competing talkers had no clear effect on the target intelligibility of interrupted (and staggered) speech and two- and four-band checkerboard speech. Still, SNRs dominated the intelligibility of two-talker checkerboard speech with equal to or more than eight frequency bands. The probability summation model may account for the intelligibility minimum in both interrupted and checkerboard speech with a single talker. The results suggest that the four speech cue channels explain the similarity of the intelligibility curves for two- and four-band checkerboard speech.