"There is a clear, unambiguous, and overwhelming conclusion: vowels are more important for recognition than the obstruent consonants, despite the fact that they are equally represented in the test sentences."
"Michael J. Owren" <mjo9@CORNELL.EDU> wrote:
We have done a study along these lines, as have Ron Cole and colleagues.
Cole et al. found that replacing consonants with noise made sentences more difficult to understand than replacing vowels with noise.
Cole, R., Yan, Y., Mak, B., Fanty, M., & Bailey, T. (1996). The contribution of consonants versus vowels to word recognition in fluent speech. International Conference on Acoustics, Speech and Signal Processing, Atlanta, GA
We found the opposite in Gina Cardillo's undergraduate honors thesis. Here listeners heard single words from which either vowels or consonants had been deleted and made same-different judgments (a signal detection design) about either word meaning or talker identity. I'm currently finishing some follow-up experiments in which all vowels in the vowels-only condition were further trimmed to eliminate coarticulation effects. Doing so has decreased word-meaning performance significantly (as expected), with less effect on talker identity cueing. These follow-up experiments should be done within a few weeks, and a manuscript should be ready not long after that.
Cardillo, G., & Owren, M. J. (2002). Relative roles of consonants and vowels in perceiving phonetic versus talker cues. Journal of Acoustical Society of America, 111, 2432.
Perceptual experiments tested whether consonants and vowels differentially contribute to phonetic versus indexical cueing in speech. In 2 experiments, 62 total participants each heard 128 American-English word pairs recorded by 8 male and 8 female talkers. Half the pairs were synonyms, while half were non-synonyms. Further, half the pairs were words from the same talker, and half from different, same-sex talkers. The first word heard was unaltered, while the second was edited by setting either all vowels ("Consonants-Only") or all consonants ("Vowels-Only") to silence. Each participant responded to half Consonants-Only and half Vowels-Only trials, always hearing the unaltered word once and the edited word twice. In Experiment 1, participants judged whether the two words had the same or different meanings. Participants in Experiment 2 indicated whether the word pairs were from the same or different talkers. Performance was measured as latencies and d'!
and indicated significantly greater sensitivity to phonetic content when consonants than vowels were heard, but the converse when talker identity was judged. These outcomes suggest important functional differences in the roles played by consonants and vowels in normative speech.
Michael J. Owren, Ph.D.
Psychology of Voice and Sound Research Lab
Department of Psychology
224 Uris Hall
Ithaca, NY 14853
(home page) http://www2.psych.cornell.edu/Owren