FUNCTIONAL DATA ANALYSES OF LIP MOTION

The vocal tract's motion during speech is a complex patterning of the movement of many different articulators according to many different ti me functions. Understanding this myriad of gestures is important to a number of different disciplines including automatic speech recognition , speech and language pathologies, speech motor control, and experimen tal phonetics. Central issues are the accurate description of the shap e of the vocal tract and determining how each articulator contributes to this shape. A problem facing all of these research areas is how to cope with the multivariate data from speech production experiments. In this paper techniques are described that provide useful tools for des cribing multivariate functional data such as the measurement pf speech movements. The choice of data analysis procedures has been motivated by the need to partition the articulator movement in various ways: en effects separated from shape effects. partitioning of syllable effects , and the splitting of variation within an articulator site from varia tion from between sites. The techniques of functional multivariate pro cedures such as analysis of variance and principal components analysis have their functional counterparts, and these reveal in a way more su ited to the data the important sources of variation in lip motion. Fin ally, it is found that the analyses of acceleration were especially he lpful in suggesting possible mechanisms. The focus is on using these s peech production data to understand the basis principles of coordinati on. However, it is believed that the tools will have a more general us e. (C) 1996 Acoustical Society of America.