Timing effects of syllable structure and stress on nasals: A real-time MRI examination

Abstract

The coordination of velum and oral gestures for English [n] is studied using real-time magnetic resonance imaging (MRI) movies to reconstruct vocal tract aperture functions. This technique allows for the examination of parts of the vocal tract otherwise inaccessible to dynamic imaging or movement tracking. The present experiment considers syllable onset, coda, and juncture geminate nasals and also addresses the effects of a variety of word stress patterns on segment internal coordination. We find a bimodal timing pattern in which near-synchrony of velum lowering and tongue tip raising characterizes the timing for onsets and temporal lag between the gestures is characteristic for codas, supporting and extending the findings for [m] of Krakow [(1989). The articulatory organization of syllables: A kinematic analysis of labial and velar gestures. Doctoral Dissertation, Yale University, New Haven, CT; (1993). Nonsegmental influences on velum movement patterns: Syllables, sentences, stress, and speaking rate. In M. A. Huffman, R. A. Krakow (Eds.), Nasals, nasalization and the velum (phonetics and phonology V) (pp. 87–116). New York: Academic Press]. Intervocalic word-internal nasals are found to have timing patterns that are sensitive to the local stress context, which suggests the presence of an underlying timing specification that can yield flexibly. We consider these findings in light of the gestural coupling structures described by Goldstein and colleagues [Goldstein, L., Byrd, D., & Saltzman, E. (2006). The role of vocal tract gestural action in units understanding the evolution of phonology. In M. Arbib (Ed.), Action to language via the mirror neuron system (pp. 215–249). Cambridge: Cambridge University Press; Goldstein, L., Nam, H., Saltzman, E., & Chitoran, I. (2008). Coupled oscillator planning model of speech timing and syllable structure. In Proceedings of the 8th phonetics conference of China and the international symposium on phonetic frontiers; Nam, H., Goldstein, L., & Saltzman, E. (in press). Self-organization of syllable structure: A coupled oscillator model. In Chitoran, Coupe, Marsico, & Pellegrino (Eds.), Approaches to phonological complexity].