The degree of similarity between L1 and L2 sounds is said to be crucial for L1/L2 sound distinction. Similar L1 and L2 sounds, according to the Speech Learning Model (SLM), tend to be undistinguished. Yet, much has been left undetermined of what counts as "similar". In this study, the relation between phonetic similarity and L1/L2 sound distinction is explored by examining whether different acoustic cues were produced for Mandarin and English when the English vowels tested were similar to the Mandarin ones (i.e. /i/, /a/, and /u/). The effect of exposure was also investigated. The results showed that Mandarin children made distinctions for the similar vowels of Mandarin and English in the dimension expected and exposure did effect how well certain vowels were discerned for the group with less exposure. The fact that L2 learners were able to pick out the differences even between similar vowels found in L1 and L2 implies a need to clarify the concept of similarity in L2 learning models.
Bibliographic reference. Wu, E-Chin (2011): "Similar vowels in L1/L2 production: confused or discerned in early L2 English learners with different amount of exposure", In INTERSPEECH-2011, 1141-1144.