Effects of Amplitude Envelope Cues as an Aid to Enhanced Speechreading

This thesis developed methods of presenting two speech envelope cues in the small bandwidth likely to be available to people with severe hearing impairments. Identifying such methods could facilitate face-to-face communication substantially. Seven presentation conditions were evaluated. Two of the conditions, the OneEnvelope Monaural and the Two-Envelope Monaural, were developed by Grant, Braida and Renn (1991), and were used as a basis of comparison to the new conditions developed. The One-Envelope "Rough" Monaural, Two-Envelope "Rough" Monaural, Simple Binaural, Combination Binaural, and Low Binaural are the five presentation conditions developed in this project. Initial tests used normal hearing subjects to evaluate each proposed scheme. This avoided compounding perceptual interference factors with hearing loss. To ensure that these tests were indicative of the full potential of each method, subjects were familiarized with the envelope cues prior to testing. Results of testing suggest that two of the new presentation conditions may prove beneficial to the hearing impaired. Both the Two-Envelope "Rough" Monaural and the Combination Binaural conditions were particularly successful in conveying speech (average scores using Harvard sentences were 74.1% and 72.1%, respectively). Thesis Supervisor: Louis D. Braida Title: Henry E. Warren Professor of Electrical Engineering