Decrease of L1–L2 assimilation and its prediction on L2 discrimination: perception of English coronal fricatives by Mandarin speakers

This study examined the perceptual assimilation and discrimination of English coronal fricatives /s, z, θ, ð/ by Mandarin speakers. The focus was on the effect of L2 experience on L1–L2 assimilation and the validity between assimilation patterns and assimilation overlaps in predicting L2 discrimination. The perceptual assimilation task showed that the more experienced group demonstrated weaker L1–L2 assimilation, corroborating the Revised Speech Learning Model (Flege, J. E. & O.-S. Bohn. 2021. The revised speech learning model. In R. Wayland (ed.), Second language speech learning: Theoretical and empirical progress, 3–83. Cambridge University Press). For the discrimination test, both more and less experienced groups performed comparably with moderate accuracy for the place contrasts /s–θ/ and /z–ð/ (assimilated as “Category-goodness”) and higher accuracy for the voice contrasts /s–z/ and /θ–ð/ (assimilated as “Two-category”). These results lent support to the predictions made by the Perceptual Assimilation Model-L2 (Best, C. T. & M. D. Tyler. 2007. Nonnative and second-language speech perception: Commonalities and complementarities. In O.-S. Bohn & M. J. Munro (eds.) Language learning & language teaching, vol. 17, 13–34. John Benjamins Publishing Company) based on the assimilation patterns (no group difference) rather than the assimilation overlaps (group difference). The current study suggested that the perceived L1–L2 similarities may decrease with the growth of L2 experience, and the place contrasts /s–θ/, /z–ð/ could render more challenges than the voice contrasts /s–z/, /θ–ð/ for Mandarin speakers. Theoretical implications were brought out through comparing controversial assimilation measurements and the effect of L2 experience on cross-language perception.