Measuring Coarticulation in Spontaneous Speech: A Preliminary Report

Abstract

UC Berkeley Phonology Lab Annual Report (2012) Measuring coarticulation in spontaneous speech: a preliminary report Melinda Fricke Keith Johnson University of California, Berkeley Introduction: why study spontaneous speech? Constantly improving processing capabilities have recently opened the door to a type of lan- guage data that was previously impossible to study: the phonetic properties of spontaneous speech. Within the past two decades in particular, studies of the acoustics of conversational speech have become more common, and more sophisticated. The present study seeks to further expand our understanding of natural speech processes by examining coarticulatory patterns in the spontaneously produced speech of adults and children. The study of spontaneous speech can shed considerable light on the workings of the language production system. In normal, everyday conversation, speakers are under quite different (and likely more stringent) pressures than in a laboratory setting. Laboratory speech is typically carefully controlled and often minimally creative; subjects often read words or sentences from a computer screen, repeating the same sentence or type of sentence many times, thus eliminating the usual need to go from concept to sentence construction to articulation. While laboratory studies have been invaluable for developing models of language production, the true testing ground for such models must be spontaneous speech, since it uniquely reveals how language production must proceed in the real world, in real time. The present study is concerned with coarticulatory patterns in particular. Coarticula- tion, the process by which any articulatory gesture affects adjacent articulatory gestures, can be anticipatory (as when knowledge of an upcoming gesture affects the realization of the gesture currently being executed) or perseverative (when an already initiated gesture carries over onto the articulatory realization of a following gesture). This study will be concerned with vowel-on-fricative coarticulation: the present research question is whether acoustic measurements can be identified that distinguish fricatives in a round vowel context from fricatives in a non-round vowel context in spontaneously produced speech. In addition to the main research question, the acoustic measurements under investigation will be ap-