Cross-frequency integration for consonant and vowel identification in bimodal hearing.
OBJECTIVE
Improved speech recognition in binaurally combined acoustic-electric stimulation (otherwise known as bimodal hearing) could arise when listeners integrate speech cues from the acoustic and electric hearing. The aims of this study were (a) to identify speech cues extracted in electric hearing and residual acoustic hearing in the low-frequency region and (b) to investigate cochlear implant (CI) users' ability to integrate speech cues across frequencies.


METHODS
Normal-hearing (NH) and CI subjects participated in consonant and vowel identification tasks. Each subject was tested in 3 listening conditions: CI alone (vocoder speech for NH), hearing aid (HA) alone (low-pass filtered speech for NH), and both. Integration ability for each subject was evaluated using a model of optimal integration--the PreLabeling integration model (Braida, 1991).


RESULTS
Only a few CI listeners demonstrated bimodal benefit for phoneme identification in quiet. Speech cues extracted from the CI and the HA were highly redundant for consonants but were complementary for vowels. CI listeners also exhibited reduced integration ability for both consonant and vowel identification compared with their NH counterparts.


CONCLUSIONS
These findings suggest that reduced bimodal benefits in CI listeners are due to insufficient complementary speech cues across ears, a decrease in integration ability, or both.
Northeastern University, Boston, MA, USA. yykong@neu.edu
Ying-Yee
YY
Kong
Louis D
LD
Braida
D000161:Acoustic Stimulation; D000328:Adult; D003054:Cochlear Implants; D003131:Combined Modality Therapy; D003463:Cues; D003638:Deafness / Q000503:physiopathology* / Q000628:therapy*; D004558:Electric Stimulation; D005260:Female; D006309:Hearing / Q000502:physiology; D006310:Hearing Aids; D006801:Humans; D008297:Male; D010700:Phonetics; D013063:Speech Discrimination Tests; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult