This research is directed toward improved speech reception for the hearing impaired. Attempts to advance basic understanding involve study of limitations imposed by characteristics of the speech signal and of the impairment, and the development of a new model of speech intelligibility that exploits ideas used in automatic speech recognition. Research on the speech signal focuses on understanding the effects of environmental disturbances (noise and reverberation), intra-speaker and inter-speaker variability of utterances, and efforts to speak clearly. Research on impairments focuses on developing and testing of techniques for simulating impairments with normals and estimating the speech reception capacity of impaired auditory systems through tests with artificial speech codes. The envisioned model of speech intelligibility includes models of perceptual processing and vector quantization, and makes use of a mutual information metric to predict intelligibility. Attempts to develop improved signal processing techniques for use in hearing aids involve study of adaptive linear filtering, amplitude compression, and frequency lowering. Also considered is an extension of articulation theory to account for speechreading and the use of this extended theory to develop effective supplements to speechreading. Attempts to apply automatic speech recognition to the development of speechreading supplements involves study of manual cued speech and the Autocuer, determination of the extent to which modern speech recognition algorithms can disambiguate speechreading, and study of auditory and visual displays for presenting speechreading supplements based on the output of automatic recognition systems to impaired listeners.
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