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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
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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.
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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
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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
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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.
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Predictions Summary of predicted categorization of gestures and predictions of relative timing by position: LipTBTRInitialFinal Sproat & Fujimura (1993) [vocalic] All three simultaneous, All three reduced All three simultaneous, No reduction Browman & Goldstein (1995) narrower constriction (than TR) narrower constriction (than TR) wider constriction All three simultaneous. TR > Lip TR > TB TB & Lip reduced Gick (2003)C-gesture V-gestureLip & TB > TR, TR reduced TR > Lip & TB Lip & TB reduced Carter (2002) ?seemingly consonantal seemingly vocalic Any order: dialect dependent (Lip)/TR > TB/(Lip) Gick et al (in press) anteriorless anteriorleast anterior All three simultaneous TR > TB > Lip
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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.
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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.
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Stimuli The position of /r/ varied within a given vocalic context such that: Syllable-initialResyllabifiableSyllable-final...V 1 # RV 1......V 1 R# V 1......V 1 R# hV 1... V 1 = /e/ (Lips, TR visible) V 1 = /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.
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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.
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Experimental Set-up
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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.
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Optotrak Marker Placement
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Ultrasound Data
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Ultrasound Measures: Timing
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Ultrasound Measures: Magnitude
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Optotrak Measures
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Qualitative Observations Sagittal diagram of idealized tongue shapes for American /r/ (Modified from Hagiwara, 1995, p.97) Tip Down Blade Up Tip Up
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Results: Timing
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Results: Magnitude
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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
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Tongue Shape Variability
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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
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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
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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
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Potential Problems Potential for error in calculations Unclear data for Resyllabifiable condition Stationary M-mode lines, variable tongue shape No head correction
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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.
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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.
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