Gestural Timing and Magnitude of English /r/: An Ultrasound-OptoTrak Study

1. Gestural Timing and Magnitude of English /r/: An Ultrasound-OptoTrak Study Fiona Campbell, Bryan Gick, Ian Wilson, and Eric Vatikiotis-Bateson Ultrafest IV Tucson, Arizona April 14, 2005

2. Goals • To better understand the gestural organization of composite segments in English. • Contribute to the knowledge of mechanisms for production of English /r/ • Improve on past methodology by testing combined B/M-mode ultrasound and Optotrak as a means to increase temporal resolution while imaging the vocal tract from lips to tongue root.

3. Introduction • Generalizations from previous studies: • Temporal: More anterior gestures appear at syllable peripheries. Nasals, /l/, /w/ (Krakow, 1999; Gick, 2003) • Spatial: Position-dependent spatial reduction of gestures. (Sproat & Fujimura, 1993) Final position reduction of anterior gestures & Initial position reduction of less anterior gestures

4. Proposed Explanations • A number of explanations have been proposed to account for these generalizations, including: • Sproat & Fujimura (1993) • Browman & Goldstein (1995) • Gick (2003) • Carter (2002) • Gick, Campbell, Oh, and Tamburri-Watt (in press) • All studies thus far have been based on a comparison of two gestures

5. English /r/ • Composed of 3 constrictions: • tongue root at the pharyngeal wall (TR) • tongue tip/blade at the palate(TB) • between the lips (Lip) • Variable tongue shape, more lip rounding and more prominent TB gesture in Initial position. (Zawadzki & Kuehn, 1980) • Examination of three gestures will help disambiguate the predictions made by different theories.

6. Predictions Summary of predicted categorization of gestures and predictions of relative timing by position:

7. Methods • Optotrak 3D motion and position measurement (point tracking) system and B/M-mode ultrasound video were used to simultaneously record the three gestures of /r/ in syllable-initial, and syllable-final positions preceding a consonant and preceding a vowel in several vocalic contexts.

8. Participants • 10 people, 5 women, 5 men • Native speakers of Canadian English • 8 from Western Canada • One of the male subjects had to be excluded from the analysis due to poor ultrasound image quality.

9. Stimuli The position of /r/ varied within a given vocalic context such that: Syllable-initial Resyllabifiable Syllable-final ...V1# RV1... ...V1R# V1... ...V1R# hV1... V1 = /e/ (Lips, TR visible) V1 = /a/ (Lips, TB visible) Stimuli were randomized and presented in a carrier phrase which was read by the subject. … said “_________” each… x 10 for each stimulus eg. Cindy said "hay ray" each afternoon.

10. Data Collection • The subject was seated in a modified ophthalmic examination chair to maximize head stability and Ultrasound probe contact. • Stimuli were presented on a laptop located about 2m away from the subject at eye level. • Timed PowerPoint presentation: 130s trials • A 'clapper' with an Optotrak marker attached was used to set a 0 point for synchronization of the Optotrak, Ultrasound, and Audio signals.

11. Experimental Set-up

12. Data Collection II • Ultrasound: B/M mode: midsagittal section (29.97fps) + continuous movement trajectories of A (TT), B (TM), C (TR) recorded to DV. • Optotrak 3020 system: recorded (at 90 Hz) the 3D positions of 12 infrared-emitting diode Optotrak markers. • Audio: signal recorded synchronized with both Optotrak and Ultrasound data signals.

13. Optotrak Marker Placement

14. Ultrasound Data

15. Ultrasound Measures: Timing

16. Ultrasound Measures: Magnitude

17. Optotrak Measures

18. Qualitative Observations Sagittal diagram of idealized tongue shapes for American /r/ (Modified from Hagiwara, 1995, p.97) Tip Down Blade Up Tip Up

19. Results: Timing

20. Results: Magnitude

21. Qualitative Results • All three tongue shapes observed • No speaker used more than two of these • ‘blade up’ was most common across subjects and most stable across positions • Tongue shape varied by both vowel context and syllable position • Higher TB syllable-initially and in the context of low or back vowels

22. Tongue Shape Variability

23. Summary • The position-based differences observed in the overall results were: • Initial • Timing: front-to-back • Spatial reduction: TR • Final: • Timing: TR & Lip simultaneous; precede TB • Spatial reduction: TB and Lips

24. Surprises? • Three-way timing distinction in Initial position • Lip patterns with TR in terms of timing but with TB in terms of spatial reduction in Final position • The results are not consistent with any of the proposals considered

25. Proposal • Timing patterns depend on magnitude • Relative width of constrictions determines order (Browman & Goldstein, 1995, but in both positions). • Narrower constriction(s) at syllable edges • Relative width can vary as a result of positional reduction • Possible motivating factor: • Constriction width: Jaw height

26. Potential Problems • Potential for error in calculations • Unclear data for Resyllabifiable condition • Stationary M-mode lines, variable tongue shape • No head correction

27. Conclusions • Accounts employing a binary categorical system are challenged by the observed three-way timing distinction in Initial position. • The results of this study suggest a dependence relationship between the relative timing of gestures and their magnitude. • Future work may be able to test this proposal by measuring the actual relative constriction width of each gesture across positions.

28. Selected References Browman, C. P., & Goldstein, L. (1992). Articulatory phonology: An overview. Phonetica, 49, 155-180. Carter, P. (2002). Structured variation in british english liquids: The role of resonance. Unpublished PhD Dissertation, University of York. Delattre, P., & Freeman, D. (1968). A dialect study of american r’s by x-ray motion picture. Linguistics, 44, 29-68. Gick, B. (1999). A gesture-based account of intrusive consonants in english. Phonology, 16, 29-54. Gick, B. (2003). Articulatory correlates of ambisyllabicity in english glides and liquids. In J. Local, R. Ogden & R. Temple (Eds.), Labphon VI: Constraints on phonetic interpretation. Cambridge: Cambridge University Press. Gick, B., Campbell, F., Oh, S., & Tamburri-Watt, L. (in press). Toward universals in the gestural organization of syllables: A cross-linguistics study of liquids. Journal of Phonetics. Hagiwara, R. (1995). Acoustic realizations of american /r/ as produced by women and men. UCLA Working Papers in Phonetics, 90, 1-187. Krakow, R. A. (1999). Physiological organization of syllables: A review. Journal of Phonetics, 27, 23-54. Sproat, R., & Fujimura, O. (1993). Allophonic variation in english /l/ and its implications for phonetic implementation. Journal of Phonetics, 21, 291-311. Uldall, E. (1958) ‘American “molar” R and “flapped” T.’ Revista do Laboratorio de Fonetica Experimental, Universidad de Coimbra 4. 103-6. Zawadzki, P. A., & Kuehn, D. P. (1980). A cineradiographic study of static and dynamic aspects of american english /r/. Phonetica, 37, 253-266.