This application describes experiments on the (mis)perception of speech cues by individuals with sensorineural hearing loss. The general approach is to use speech and speech-like stimuli, as opposed to typical psychoacoustic stimuli. The experiments identify the types of speech segments and cues that are recognized incorrectly by hearing-impaired listeners. A measure of audibility based upon the short-term spectrum of speech sounds is used to separate the contribution of reduced audibility (i.e., errors due to speech cues presented below listener's thresholds) from the contribution of suprathreshold factors. Extensive studies of the levels of speech stimuli and audibility of individual speech sounds are also described. Additional experiments are proposed to identify the specific types of suprathreshold speech cures (described in physical terms, i.e., formant transitions, speech envelope cues, etc.) that present difficulties for the hearing-impaired individual. The objective is to search for common characteristics of these """"""""problem speech cues"""""""" in order to lay the ground work for a comprehensive approach to explaining suprathreshold speech errors. Follow-up experiments will investigate the effects of modifying these speech cures upon their ability to be used by hearing-impaired subjects. Strategies including compression, and recording of formant transitions will be tested. The effect of long-term training upon listeners' abilities to use these modified cues will also be studied. The overall objective is to identify the types of speech cues that will require more than amplification to maximize speech recognition by patients and to investigate the bases for these results. The use of speech and speech-like signals is a unique approach in studying hearing loss, in that the specific problems of hearing-impaired subjects to use various speech cues can be studied directly. This knowledge has application to both improved use of existing hearing aid technologies, and also to improving future hearing aids.
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