2010/01/06

Garcia-Sierra, A., Diehl, R. L., & Champlin, C. (2009). Testing the double phonemic boundary in bilinguals. Speech Communication, 51, 369–378.

Presentation: Angela

Summary: Shelly

There has been a long tradition on the debate of whether bilinguals have double phonetic boundaries in their linguistic systems. One side of the studies found that bilinguals showed boundary shift when facing different languages, which suggested they have double phonetic boundaries, and it was also found that the shifting of boundary increases with proficiency of bilinguals’ L2. However, the other side of studies failed to find such boundary shifting and claimed that there is no difference between the phonetic boundary of bilinguals and monolinguals. In order to see whether bilinguals possess a double phonemic representation, and whether this phenomenon is unique to bilinguals, the present study performed a speech categorization test to both bilinguals and monolinguals. Stimuli were tokens from a speech continuum between /ga/ to /ka/, where the VOT varied from –100 ms to 100 ms in 10 ms steps. Subjects were asked to identify each token as either /ga/ or /ka/, and some of the stimuli contained precursor sentences, which functioned as a cue to phonetic contexts. The whole procedure proceeded once in English, and once in Spanish, from which the authors intended to examine the effect of language on subjects’ performance. Results showed that there indeed is a significant main effect of language, where for both bilinguals and monolinguals, their boundary position for /ga/ and /ka/ differs in English and in Spanish, and the reason for monolinguals to show such a boundary shift was explained by the authors that these monolinguals also had some knowledge of Spanish. However, ANOVA tests failed to show significant difference between bilinguals and monolinguals. The author performed a correlation test for further examination, and the results showed that the amount of boundary shifting actually correlateed with subjects’ proficiency in Spanish, implying that proficiency of L2 is determinant for boundary shifting. In addition, there is no difference between results of stimuli with and without precursor sentences, which suggested that phonetic context does not have a role here. Therefore, from the above findings, the present study concluded that double phonetic boundaries do exist, and language proficiency, instead of phonetic environment, plays an important role in this regard.