Abstract:

The use of magnetic resonance imaging (MRI) in speech research has, typically, been limited to static, sustainable vocal tract configurations due to the long acquisition times required [e.g., Baer et al., J. Acoust. Soc. Am. 90, 799--828 (1991)]. This work describes the application of a synchronized MRI sampling technique developed for cardiac motion imaging to the visualization of dynamic articulatory movements. Subjects produced 128 repetitions of a target utterance (/tata/ and /kaka/) coincident with audible tone bursts synchronized with gating pulses controlling MRI scanning. During each repetition, 35 scans at 25-ms intervals were acquired, each scan providing one row of frequency-domain data for each of the 35 output frames. After repetitive scans were completed, the full sequence was processed to give a 40-frames-per-second midsagittally oriented movie. Analysis of the resulting movies revealed that tongue shapes for the interconsonantal /a/ varied between the two utterance types, indicating a place-of-articulation effect of consonants on coproduced vowel tongue shape. This suggests that the synchronized sampling method provides a practical technique for investigation of the dynamic characteristics of articulatory movements during short utterances.