Invariant principles of speech motor control that are not language-specific

Abstract

Bilingual speakers must learn to modify their speech motor control mechanism based on the linguistic parameters and rules specified by the target language. This study examines if there are aspects of speech motor control which remain invariant regardless of the first (L1) and second (L2) language targets. Based on the age of academic exposure and proficiency in L2, 21 Bengali–English bilingual participants were classified into high (n = 11) and low (n = 10) L2 (English) proficiency groups. Using the Optotrak 3020 motion sensitive camera system, the lips and jaw movements were recorded while participants produced Bengali (L1) and English (L2) sentences. Based on kinematic analyses of the lip and jaw movements, two different variability measures (i.e., lip aperture and lower lip/jaw complex) were computed for English and Bengali sentences. Analyses demonstrated that the two groups of bilingual speakers produced lip aperture complexes (a higher order synergy) that were more consistent in co-ordination than were the lower lip/jaw complexes (a lower order synergy). Similar findings were reported earlier in monolingual English speakers by Smith and Zelaznik. Thus, this hierarchical organization may be viewed as a fundamental principle of speech motor control, since it is maintained even in bilingual speakers.

Keywords::

• Bengali
• speech motor control
• bilingualism
• second language learning
• functional synergy

Acknowledgements

I am grateful to Lisa Goffman, Anne Smith, Howard Zelaznik, Janna Berlin, and Stefanie Westover for invaluable assistance with many phases of this work. Special thanks to Diana Gonzales and Katrina Harris. This work was supported by the National Institutes of Health (National Institute of Deafness and other Communicative Disorders) grant DC04826.

Declaration of interest: The author report no conflicts of interest. The author alone is responsible for the content and writing of the paper.