Speech intelligibility in cochlear implant simulations: Effects of carrier type, interfering noise, and subject experience

Channel vocoders using either tone or band-limited noise carriers have been used in experiments to simulate cochlear implant processing in normal-hearing listeners. Previous results from these experiments have suggested that the two vocoder types produce speech of nearly equal intelligibility in qui...

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Veröffentlicht in:The Journal of the Acoustical Society of America Jg. 122; H. 4; S. 2376
Hauptverfasser: Whitmal, Nathaniel A, Poissant, Sarah F, Freyman, Richard L, Helfer, Karen S
Format: Journal Article
Sprache:Englisch
Veröffentlicht: United States 01.10.2007
Schlagworte:
Adult
Auditory Threshold
Cochlear Implants
Cues
Female
Humans
Perceptual Masking
Phonetics
Social Environment
Sound Spectrography
Speech Discrimination Tests
Speech Perception
ISSN:1520-8524, 1520-8524
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Zusammenfassung:Channel vocoders using either tone or band-limited noise carriers have been used in experiments to simulate cochlear implant processing in normal-hearing listeners. Previous results from these experiments have suggested that the two vocoder types produce speech of nearly equal intelligibility in quiet conditions. The purpose of this study was to further compare the performance of tone and noise-band vocoders in both quiet and noisy listening conditions. In each of four experiments, normal-hearing subjects were better able to identify tone-vocoded sentences and vowel-consonant-vowel syllables than noise-vocoded sentences and syllables, both in quiet and in the presence of either speech-spectrum noise or two-talker babble. An analysis of consonant confusions for listening in both quiet and speech-spectrum noise revealed significantly different error patterns that were related to each vocoder's ability to produce tone or noise output that accurately reflected the consonant's manner of articulation. Subject experience was also shown to influence intelligibility. Simulations using a computational model of modulation detection suggest that the noise vocoder's disadvantage is in part due to the intrinsic temporal fluctuations of its carriers, which can interfere with temporal fluctuations that convey speech recognition cues.
Bibliographie:ObjectType-Article-2
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ISSN:1520-8524
1520-8524
DOI:10.1121/1.2773993