No abstract

The language environment modifies the speech perception abilities found in early development. In particular, adults have difficulty perceiving many nonnative contrasts that young infants discriminate. The underlying perceptual reorganization apparently occurs by 10-12 months. According to one view, it depends on experiential effects on psychoacoustic mechanisms. Alternatively, phonological development has been held responsible, with perception influenced by whether the nonnative sounds occur allophonically in the native language. We hypothesized that a phonemic process appears around 10-12 months, which assimilates speech sounds to native categories whenever possible; otherwise, they are perceived in auditory or phonetic (articulatory) terms. We tested this with English-speaking listeners, using Zulu click contrasts. Adults discriminated the click contrasts; performance on the most difficult (80% correct) was not diminished even when the most obvious acoustic difference was eliminated. Infants showed good discrimination of the acoustically-modified contrast even by 12-14 months. Together with earlier reports of developmental change in perception of nonnative contrasts, these findings support a phonological explanation of language-specifiC reorganization in speech perception.

Classic non-native speech perception findings suggested that adults have difficulty discriminating segmental distinctions that are not employed contrastively in their own language. However, recent reports indicate a gradient of performance across non-native contrasts, ranging from near-chance to near-ceiling. Current theoretical models argue that such variations reflect systematic effects of experience with phonetic properties of native speech. The present research addressed predictions from Best's perceptual assimilation model (PAM), which incorporates both contrastive phonological and noncontrastive phonetic influences from the native language in its predictions about discrimination levels for diverse types of non-native contrasts. We evaluated the PAM hypotheses that discrimination of a non-native contrast should be near-ceiling if perceived as phonologically equivalent to a native contrast, lower though still quite good if perceived as a phonetic distinction between good versus poor exemplars of a single native consonant, and much lower if both non-native segments are phonetically equivalent in goodness of fit to a single native consonant. Two experiments assessed native English speakers' perception of Zulu and Tigrinya contrasts expected to fit those criteria. Findings supported the PAM predictions, and provided evidence for some perceptual differentiation of phonological, phonetic, and nonlinguistic information in perception of non-native speech. Theoretical implications for non-native speech perception are discussed, and suggestions are made for further research.

This study examined the perception of the four Mandarin lexical tones by Mandarin-naïve Hong Kong Cantonese, Japanese, and Canadian English listener groups. Their performance on an identification task, following a brief familiarization task, was analyzed in terms of tonal sensitivities (A-prime scores on correct identifications) and tonal errors (confusions). The A-prime results revealed that the English listeners' sensitivity to Tone 4 identifications specifically was significantly lower than that of the other two groups. The analysis of tonal errors revealed that all listener groups showed perceptual confusion of tone pairs with similar phonetic features (T1-T2, T1-T4 and T2-T3 pairs), but not of those with completely dissimilar features (T1-T3, T2-T4, and T3-T4). Language specific errors were also observed in their performance, which may be explained within the framework of the Perceptual Assimilation Model (PAM: Best, 1995;Best & Tyler, 2007). The findings imply that linguistic experience with native tones does not necessarily facilitate non-native tone perception. Rather, the phonemic status and the phonetic features (similarities or dissimilarities) between the tonal systems of the target language and the listeners' native languages play critical roles in the perception of non-native tones.