title: Benefits of preserving stationary and time-varying formant structure in alternative representations of speech: implications for cochlear implants.
abstract: Cochlear implants have improved speech recognition for deaf individuals, but further modifications are required before performance will match that of normal-hearing listeners. In this study, the hypotheses were tested that (1) implant processing would benefit from efforts to preserve the structure of the low-frequency formants and (2) time-varying aspects of that structure would be especially beneficial. Using noise-vocoded and sine-wave stimuli with normal-hearing listeners, two experiments examined placing boundaries between static spectral channels to optimize representation of the first two formants and preserving time-varying formant structure. Another hypothesis tested in this study was that children might benefit more than adults from strategies that preserve formant structure, especially time-varying structure. Sixty listeners provided data to each experiment: 20 adults and 20 children at each of 5 and 7 years old. Materials were consonant-vowel-consonant words, four-word syntactically correct, meaningless sentences, and five-word syntactically correct, meaningful sentences. Results showed that listeners of all ages benefited from having channel boundaries placed to optimize information about the first two formants, and benefited even more from having time-varying structure. Children showed greater gains than adults only for time-varying formant structure. Results suggest that efforts would be well spent trying to design processing strategies that preserve formant structure.
authors.affiliation: Department of Otolaryngology, The Ohio State University, 915 Olentangy River Road, Suite 4000, Columbus, Ohio 43212.
authors.forename: Susan
authors.initials: S
authors.lastname: Nittrouer
authors.affiliation: Department of Otolaryngology, The Ohio State University, 915 Olentangy River Road, Suite 4000, Columbus, Ohio 43212.
authors.forename: Joanna H
authors.initials: JH
authors.lastname: Lowenstein
authors.affiliation: Department of Otolaryngology, The Ohio State University, 915 Olentangy River Road, Suite 4000, Columbus, Ohio 43212.
authors.forename: Taylor
authors.initials: T
authors.lastname: Wucinich
authors.affiliation: Department of Otolaryngology, The Ohio State University, 915 Olentangy River Road, Suite 4000, Columbus, Ohio 43212.
authors.forename: Eric
authors.initials: E
authors.lastname: Tarr
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001302:Audiometry, Speech; D001309:Auditory Threshold; D002648:Child; D002675:Child, Preschool; D003054:Cochlear Implants; D006801:Humans; D019986:Persons with Hearing Disabilities / Q000523:psychology / Q000534:rehabilitation*; D021641:Recognition, Psychology; D013061:Speech Acoustics; D013067:Speech Perception; D013997:Time Factors; D055815:Young Adult