2011K Restoration of interrupted speech: What does it teach us for top-down speech repair in hearing impaired?

Inaudible parts of speech can be perceptually restored with the help of linguistic knowledge, context, and expectations. This top-down repair mechanism, phonemic restoration, is considered to enhance speech intelligibility in noisy environments. Hearing-impaired listeners and users of cochlear implants commonly complain about not understanding speech in noise. In our research, we observe that hearing impairment and frontend processing of hearing aids and cochlear implants may reduce the benefit from restoration. Based on this observation, we hypothesize that the degradations in the bottom-up speech signals due to the hearing impairment or signal processing may have a negative effect on the top-down repair mechanism, which could partially be responsible for the complaints by this population. We test this hypothesis in a number of studies with either control groups of normal hearing (with or without simulations of hearing impairment) or with hearing-impaired participants. In this talk, I will present results from these studies. Overall findings from our laboratory imply that the degradations in the bottom-up signals alone (such as in hearing impairment) may reduce the top-down restoration of speech, even in the absence of cognitive deficits.