No Access Submitted: 19 February 2014 Accepted: 28 August 2014 Published Online: 23 October 2014
The Journal of the Acoustical Society of America 136, 1845 (2014);
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  • Susan Nittrouer
  • Joanna H. Lowenstein
  • Taylor Wucinich
  • Eric Tarr
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.
The authors wish to thank Jamie Kuess for writing the software to present stimuli. This work was supported by Grant No. R01 DC000633 from the National Institutes of Health, National Institute on Deafness and Other Communication Disorders.
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