A visible cue for CVC-final consonant voicing (Ted Moallem )


Subject: A visible cue for CVC-final consonant voicing
From:    Ted Moallem  <ted.moallem@xxxxxxxx>
Date:    Thu, 1 Sep 2011 15:42:21 -0400
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

Dear List, I'm wondering if anyone can point me to references concerning a particular visual speechreading phenomenon that I've encountered in my research, developing a speech aid the Deaf and hearing-impaired. As part of the study, my subjects performed a pairwise consonant discrimination task under two sensory conditions: lipreading-alone and lipreading+speech-aid. As expected, in the lipreading-alone condition, corresponding voiced and unvoiced consonants (e.g., /b/-/p/ or /d/-/t/) are virtually indistinguishable in CVC-initial context. However, in CVC-final context, most subjects discriminate consonant voicing well above chance, just through lipreading (unaided). Performance is far from perfect, but d' > 1 is the norm, and a few subjects (both hearing-impaired and normal-hearing) consistently score d' ≥ 2. My working theory is that the duration of the vowel (or of the CVC utterance as a whole) is providing a visible cue that is correlated with CVC-final consonant voicing. Vowel duration as an acoustic cue for final consonant voicing is well-known (e.g., House and Fairbanks, 1953; Denes, 1955; House, 1961; Raphael, 1972; Mack, 1982; Luce and Charles-Luce, 1985). But I cannot seem to find a paper that describes or even refers to the visual correlate. I assume that visual cues for final consonant voicing are well-characterized somewhere in the lipreading literature. Perhaps I'm using the wrong search terms. In any case, I'd appreciate the benefit of your collective expertise. Thanks in advance! Ted -- ________________________________ Theodore Moallem, Ph.D. moallem@xxxxxxxx 646-872-0283 http://www.BlindLead.org -- Sensory Communication Group Research Laboratory of Electronics @xxxxxxxx MIT Harvard-MIT Division of Health Sciences and Technology


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