Effects of fundamental-frequency dynamics on sentence intelligibility in competing-talker scenarios

Differences in the fundamental-frequency (F0) dynamic range between competing voices (i.e., an F0-dynamic-range contrast) have recently been shown to facilitate the perceptual separability of the target speech from the interfering speech. This effect was observed when pairing natural voices with different levels of intonation and using a fixed combination of target and masking talkers. The present study extended these findings by using a larger variety of talkers, F0-dynamic-range levels and F0-dynamicrange contrasts. Target-speech intelligibility was measured in young normal-hearing listeners as a function of the F0-dynamic-range contrast between two competing sentences (spoken by the same talker and digitally manipulated in F0) that had either the same or different average F0. Speech intelligibility (i) was only moderately affected by the F0-dynamic-range contrast, independent of the difference in average F0, (ii) was lowest when both sentences had a small F0 dynamic range, and (iii) increased when a moderate F0-dynamic-range was introduced in at least one of the sentences, regardless of the F0-dynamic-range contrast between them. These findings suggest that the qualitative dissimilarity between the F0 trajectories of competing sentences, rather than their F0-dynamic-range contrast, aids speech intelligibility.