By Andries W. Coetzee
Nov 10, 2012
Jon Yip recently gave a presentation at the 164th Meeting of the Acoustical Society of America in Kansas City. The ASA meeting remains one of the premier venues to present research on speech production and perception. It is an occasion for researchers from across many different fields in speech science to meet and exchange ideas. Jon presented on his dissertation research about the coordination of articulatory gestures in Modern Greek consonant clusters.
Over the past four or five years, the Michigan Phonetics Lab has expanded its research focus to also include explorations in articulatory phonetics. Our graduate students have taken an active role in this development. Susan Lin (PhD 2011) used ultrasound imaging techniques to investigate the articulation of laterals in American English. Jon also relies on ultrasound imaging to probe into the lingual gestures involved in the production of Greek consonant clusters. However, Jon is adding another component to his research. In addition to studying lingual movements using ultrasound, Jon also uses a high speed digital camera to record the movement of the lips during production of the consonant clusters. This enables Jon to investigate the detailed timing relationship between both lingual and labial articulators, and it puts him on the forefront of methodological developments in research on speech production.
The title and abstract of Jon's ASA presentation is given below.
Linguistic Effects on the Timing of Gestural Coordination in Modern Greek CC Sequences
Previous studies have shown that gestural timing in consonant clusters is influenced by position in the word, order of place of articulation, and manner of articulation (Byrd, 1996; Chitoran et al., 2002; Chitoran & Goldstein, 2006; Kü¨hnert et al., 2006). However, whether these effects are due to biomechanical constraints on production, perceptual-recoverability (acoustic masking) factors, or language-specific patterns – or some combination of these – remains controversial.
This ultrasound and lip video study of Modern Greek speakers’ initial CC productions investigates the source of the effects of place order (front-to-back, back-to-front) and manner (plosive, fricative, liquid) on articulatory lag between C1 and C2. For all CC in this study, C2 is coronal; C1 is labial or velar. Both biomechanical and perception-oriented accounts predict greater lag for back-to-front than front-to-back clusters. A perception-oriented account also predicts an effect of C1 and C2 manner on gestural lag when acoustic masking is most likely, that is, when initial CC order is back-to-front. A biomechanical account predicts no such manner effect.
Consistent with both hypotheses and previous findings, a global effect of place order was found: gestural lag is greater in back-to-front [kt ks kl xt] than in front-to-back [pt ps pl ft] clusters. For CC productions of two of the three speakers, gestural lag is also influenced by manner: plosive-plosive sequences overlap less than other manner combinations, but – contrary to perceptual predictions – only for the front-to-back sequences. It is argued that this seemingly unexpected manner effect is likely due to overall back-to-front gestural lag that is sufficiently large such that acoustic masking is not a factor. Perceptual testing is needed to assess this interpretation.