Over the years linguists have studied and explained the sound systems of language in terms of "sounds". Our words for this area of study "Phonetics" and "Phonology" even employ the Greek root for sound: phon. Yet, language is acquired in face-to-face communication in which children watch as well as listen as adults model language. The PI has found that phonetic explanations of sound change sometimes fail because they refer only to muscular or acoustic properties of speech neglecting what talking faces look like. The proposed research identifies five such problem spots in current thinking, presents the rationale for hypothesizing that visual phonetic information may be involved, and outlines proposed tests of these hypotheses. The ultimate goal is a workable theory of language change that will make it possible to predict future trends.
The first set of three audiovisual perception studies in this project will examine the potential impact of visual phonetic cues in historical sound changes involving place of articulation. These include studies on the "unmarked" status of coronal consonants, the emergence of glottal stop from homorganic consonant clusters, and the role of secondary labialization in the preservation of bilabial and labiodental consonants. The second set of two studies will again use audiovisual speech perception experiments but in this set the emphasis is on dialect variation in American English, dealing specifically with the role of visual phonetic cues for vowels and fricative consonants. Two visual phonetic descriptive studies, one on low vowels and one on interdental fricatives will be conducted and to provide the empirical basis for the perception experiments.
In addition to its contribution to the understanding of how humans perceive spoken language and the effect that visual information has on speech perception, this research project will integrate education and research by providing valuable research opportunities for undergraduates and graduate students. It will broaden the participation of under-represented groups through the involvement of students at community colleges. It will also result in the broad dissemination of research through publications in specialist journals and timely web publication of results and raw materials.
