ISCA Workshop on Plasticity in Speech Perception (PSP2005)
Senate House, London, UK
It is well known that the first language (L1) exerts a strong influence on the production/perception of non-native sounds. Theories of cross-language perception posit that perceived relation between native and non-native sounds plays an important role in predicting discrimination accuracy of nonnative sound contrasts. This study examined the ability of three groups of listeners differing in L1 to discriminate native and/or non-native stops. Native speakers of Australian English (AE) and Japanese and Thai speakers with varying degrees of experience with English participated and their discrimination of three stop place contrasts (/p/-/t/, /p/-/k/, /t/-/k/) in English and Thai was assessed.
Listeners' L1s differed markedly with respect to the occurrence of word-final stops. All stop contrasts tested in this study occur in English and Thai and are known/familiar to these listeners but they differ in phonetic realization, i.e., variably released in English and invariably unreleased in Thai. In Japanese, on the other hand, the predominant syllable structure is /(C)V/ and English words such as 'cap' and 'cat' are expected to be difficult for Japanese listeners to discriminate. These cross-linguistic differences lead to the expectations that AE and Thai listeners would discriminate stop contrasts in English and Thai accurately while Japanese listeners would discriminate them poorly.
Monosyllabic words ending with stop tokens were presented in triads to listeners whose task was to identify an odd item out if any. All three groups of listeners showed accurate discrimination of English stop contrasts, but only Thai listeners were able to discriminate Thai stop contrasts accurately. In general, AE listeners discriminated Thai stops significantly more accurately than Japanese listeners but less accurately than Thai listeners. AE and Japanese listeners' discrimination accuracy of Thai stimuli differed according to the contrast type tested and both groups were more variable than Thai listeners.
Although Japanese listeners had no experience with word-final stops in the L1, they were able to discriminate English contrasts (but not Thai contrasts) accurately, demonstrating that non-native contrasts are learnable and that some aspects of speech perception remains plastic beyond early childhood. Taken together with the finding that AE listeners did not match Thai listeners in discriminating Thai stops despite their experience with unreleased stops in the L1 suggests that phonetic realization of sounds and/or the amount of acoustic information contained in the speech signal may influence accuracy with which sound contrasts are discriminated.
Bibliographic reference. Tsukada, Kimiko (2005): "Cross-language speech perception of final stops by Australian-English, Japanese and Thai listeners", In PSP2005, 244-247.