Patterns of velum coordination in Brazilian Portuguese Leonardo Oliveira1,2, Stefania Marin2 1 Haskins Laboratories, 2Yale University
[email protected],
[email protected]
Time f rom achiev ement of target of oral gesture to target of v elum gesture
It has been observed for Brazilian Portuguese that consonant clusters of the type [nd] (e.g. partindo ‘leaving’) are often heard as [n] in fast speech. In this talk, we propose to explain this alternation within the theory of Articulatory Phonology (AP), and to provide empirical evidence as to why such an analysis is warranted and in fact preferred. A major claim of AP is that gestures (its minimal units) can be viewed as coupled oscillators, and a specific coupling of gestures yields a wealth of observable cross-linguistic effects ([1], [2], [5]). The proposal here is that the nasal (i.e. velum) gesture in coda position is sequentially (anti-phase) coupled with the preceding vowel. However, it has been shown that at fast rates, there is spontaneous shift from anti-phase (sequential) coordination to inphase (synchronous) coordination ([2], [6]). Given this, it is proposed that at fast rates the nasal coda gesture in Portuguese shifts from being sequentially coordinated with the vowel to being synchronously coordinated with the following gesture. Thus, the apparent effect of oral consonant deletion is not categorical deletion of an oral consonant, but gestural reorganization due to an unstable pattern between the velum and the oral gesture in the coda. The prediction of this proposal is that this reorganization should occur whenever there is speech production instability (e.g. fast speech rates), and it should result in a gestural overlap pattern more similar to that observed in onsets (i.e. in-phase coordination). This proposal is supported by preliminary kinematic data (EMMA, [4]) from one speaker of Brazilian Portuguese (the complete study will include data from at least two more speakers). Seven triads were used to compare the production of [nd] vs. [n] vs. [d] (e.g. partindo ‘leaving’, partido ‘cracked’, patino ‘I skate’) at various speech rates. The speaker’s task was to synchronize the production of the word with a visual signal presented in stepwise decreasing intervals. Gestural coordination was quantified as the time between gestural landmarks, algorithmically derived from local velocity profiles of the relevant receivers in the vocal tract. The selected gestural landmark employed was achievement of target, which has been independently shown to capture the changes in coordination patterns for consonant clusters ([3]). Sequential coordination yields a positive lag between achievement of velum gesture and oral constriction, while synchronous coordination results in negative or close to zero lag between the two. The analysis (Fig. 1) showed that at fast rates, relative timing between achievement of targets becomes more variable and eventually shifts, in some tokens, to negative values, a pattern closer to onset values. [Work supported by NIH Grant HD-01994] 80 60 40 20 0
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References: [1] Browman, C. P. and L. Goldstein. 1995. Gestural Syllable Position Effects in American English. In Producing Speech: Contemporary Issues, F. Bell-Berti and L. J. Raphael (eds.), 19-34. Woodbury, NY: American Institute of Physics. [2] Krakow, R. A. 1993. Nonsegmental influences on velum movement patterns: Syllables, sentences, stress and speaking rate. In M. K. Huffman and R. A. Krakow (eds.) Phonetics and phonology, Volume 5: Nasals, nasalization, and the velum, 87-116. New York: Academic Press. [3] Oliveira, L., M. Yanagawa, L. Goldstein and I. Chitoran. 2004. Towards standard measures of articulatory timing. Journal of the Acoustical Society of America 116, 264344. [4] Perkell, J., Cohen, M., Svirsky, M., Matthies, M., Garabieta, I., and Jackson, M. 1992. Electro-magnetic midsagittal articulometer (EMMA) systems for transducing speecharticulatory movements. Journal of Acoustical Society of America 92, 3078-3096. [5] Saltzman, E. L. 1995. Dynamics and Coordinate Systems in Skilled Sensorimotor Activity. In Mind as Motion, T. van Gelder & R. F. Port (eds), 149-173. Cambridge, Mass: MIT Press [6] Tuller, B. and J. A. S. Kelso. 1990. Phase transitions in speech production and their perceptual consequences. In M. Jeannerod (ed.) Attention and performance XIII. Hillsdale, NJ: Erlbaum.
