The role of continuous low-frequency harmonicity cues for interrupted speech perception in bimodal hearing

Abstract

Low-frequency acoustic cues have been shown to enhance speech perception by cochlear-implant users, particularly when target speech occurs in a competing background. The present study examined the extent to which a continuous representation of low-frequency harmonicity cues contributes to bimodal benefit in simulated bimodal listeners. Experiment 1 examined the benefit of restoring a continuous temporal envelope to the low-frequency ear while the vocoder ear received a temporally interrupted stimulus. Experiment 2 examined the effect of providing continuous harmonicity cues in the low-frequency ear as compared to restoring a continuous temporal envelope in the vocoder ear. Findings indicate that bimodal benefit for temporally interrupted speech increases when continuity is restored to either or both ears. The primary benefit appears to stem from the continuous temporal envelope in the low-frequency region providing additional phonetic cues related to manner and F1 frequency; a secondary contribution is provided by low-frequency harmonicity cues when a continuous representation of the temporal envelope is present in the low-frequency, or both ears. The continuous temporal envelope and harmonicity cues of low-frequency speech are thought to support bimodal benefit by facilitating identification of word and syllable boundaries, and by restoring partial phonetic cues that occur during gaps in the temporally interrupted stimulus.

Age effects on the contributions of envelope and periodicity cues to recognition of interrupted speech in quiet and with a competing talker

“…For both younger and older adults, envelope and periodicity cues provided additive contributions to recognition of interrupted speech. Consistent with recent work by Oh et al (2016), keyword recognition in sentences was best when both cues were available. Here, results suggested a larger effect of envelope cues than periodicity cues both in quiet and with a competing talker.…”