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Articulatory feature encoding and sensorimotor training for tactually supplemented speech reception by the hearing-impaired

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dc.contributor.advisor Louis D. Braida. en_US
dc.contributor.author Moallem, Theodore M., 1976- en_US
dc.contributor.other Harvard University--MIT Division of Health Sciences and Technology. en_US
dc.date.accessioned 2012-01-12T19:29:01Z
dc.date.available 2012-01-12T19:29:01Z
dc.date.copyright 2011 en_US
dc.date.issued 2011 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/68454
dc.description Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2011. en_US
dc.description Cataloged from PDF version of thesis. en_US
dc.description Includes bibliographical references (p. 150-159). en_US
dc.description.abstract This thesis builds on previous efforts to develop tactile speech-reception aids for the hearing-impaired. Whereas conventional hearing aids mainly amplify acoustic signals, tactile speech aids convert acoustic information into a form perceptible via the sense of touch. By facilitating visual speechreading and providing sensory feedback for vocal control, tactile speech aids may substantially enhance speech communication abilities in the absence of useful hearing. Research for this thesis consisted of several lines of work. First, tactual detection and temporal order discrimination by congenitally deaf adults were examined, in order to assess the practicability of encoding acoustic speech information as temporal relationships among tactual stimuli. Temporal resolution among most congenitally deaf subjects was deemed adequate for reception of tactually-encoded speech cues. Tactual offset-order discrimination thresholds substantially exceeded those measured for onset-order, underscoring fundamental differences between stimulus masking dynamics in the somatosensory and auditory systems. Next, a tactual speech transduction scheme was designed with the aim of extending the amount of articulatory information conveyed by an earlier vocoder-type tactile speech display strategy. The novel transduction scheme derives relative amplitude cues from three frequency-filtered speech bands, preserving the cross-channel timing information required for consonant voicing discriminations, while retaining low-frequency modulations that distinguish voiced and aperiodic signal components. Additionally, a sensorimotor training approach ("directed babbling") was developed with the goal of facilitating tactile speech acquisition through frequent vocal imitation of visuo-tactile speech stimuli and attention to tactual feedback from one's own vocalizations. A final study evaluated the utility of the tactile speech display in resolving ambiguities among visually presented consonants, following either standard or enhanced sensorimotor training. Profoundly deaf and normal-hearing participants trained to exploit tactually-presented acoustic information in conjunction with visual speechreading to facilitate consonant identification in the absence of semantic context. Results indicate that the present transduction scheme can enhance reception of consonant manner and voicing information and facilitate identification of syllableinitial and syllable-final consonants. The sensorimotor training strategy proved selectively advantageous for subjects demonstrating more gradual tactual speech acquisition. Simple, low-cost tactile devices may prove suitable for widespread distribution in developing countries, where hearing aids and cochlear implants remain unaffordable for most severely and profoundly deaf individuals. They have the potential to enhance verbal communication with minimal need for clinical intervention. en_US
dc.description.statementofresponsibility by Theodore M. Moallem. en_US
dc.format.extent 159 p. en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582 en_US
dc.subject Harvard University--MIT Division of Health Sciences and Technology. en_US
dc.title Articulatory feature encoding and sensorimotor training for tactually supplemented speech reception by the hearing-impaired en_US
dc.type Thesis en_US
dc.description.degree Ph.D. en_US
dc.contributor.department Harvard University--MIT Division of Health Sciences and Technology. en_US
dc.identifier.oclc 769122565 en_US


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