Influence Of First Language Background And Stimulus Type On Categorical Perception Of Mandarin Tones

Based on different use of pitch information in their prosodic systems,languages in the world can be generally classified into tone and non-tone languages.Mandarin Chinese,as a tone language,employs different tones(i.e.,pitch patterns)to distinguish lexical meanings.Mandarin tones have a variety of pitch contours and pitch heights,which brings great difficulty to learners of Chinese as a foreign language(CFL).Conspicuous foreign accents are usually discernible from these CFL learners’ utterances.As one of the two basic modes of speech perception,categorical perception offers a much more refined method to explore the perception patterns of lexical tones.Prior studies on the categorical perception of lexical tones have mostly been conducted from two perspectives: the influence of language experience and the influence of stimulus type.For the former,most prior research centered on the impact of non-tone language background by comparison with tone language background.However,previous studies on the impact of different tone systems have primarily focused on Cantonese,while other tone languages in other countries have been rarely studied,such as Thai and Vietnamese.For the latter,previous studies have mainly compared the effect of speech stimuli and nonspeech stimuli on categorical tone perception,but their findings were inconsistent.Some reported that categorical perception is restricted to a special,speech-specific mode,whereas others held that categorical perception is domain-general.Based on this situation,using the traditional paradigm of categorical perception,the current study aims to further explore the influence of first language background on the perception of non-native tones by comparing the perception patterns of Mandarin tones by native Russian speakers(non-tone language)and native Vietnamese speakers(tone language which has different tone system from Mandarin)from the acoustic perspective.Moreover,by comparing the perception patterns of speech stimuli and nonspeech stimuli,the current study also attempts to investigate the influence of stimulus type on categorical tone perception.It specifically discussed the following three research questions:1.How do native Russian and Vietnamese listeners perceive Mandarin tone continua respectively in terms of categorical perception?2.How does language background account for the tone perception similarities and differences between native Mandarin listeners and these two non-native language groups?3.How does stimulus type influence the tone perception performances of these three language groups?This experimental study involved three language groups,namely native Mandarin listeners,native Russian listeners,and native Vietnamese listeners.Each group consisted of 10 participants.The experimental materials were four 11-step pitch continua synthesized by Praat,to be more specific,two directions,i.e.,rising(Tone2-Tone 1)vs.falling(Tone 4-Tone 1),two stimulus types,i.e.,speech(tone)vs.nonspeech(pure tone).Since there has been a lot of controversy over the perception pattern of the continuum of Mandarin Tone 2 and Tone 3,the current study did not take this continuum into consideration.The duration and intensity of each stimulus were normalized in order to ensure the primary role of pitch in this study.The whole experiment was divided into two parts: identification tasks and discrimination tasks.The identification tasks required each participant to identify the tone of the presented stimulus,whereas the discrimination tasks required each participant to determine whether the two presented stimuli bear the same tone or different tones.The identification and discrimination curves were drawn based on their experimental results.By using the data analysis methods described in Xu et al.(2006)and Peng et al.(2010),three parameters were calculated: the category boundary position,the category boundary width,and the discrimination accuracy.The major findings were summarized below:1.Native Mandarin and Vietnamese listeners perceived Mandarin lexical tones categorically,but their identification and discrimination curves were slightly different because of their different tone systems.However,native Russian listeners perceived Mandarin tones in a continuous manner due to their non-tone language background.2.First language background did modulate these three language groups’ tone perception performances.In terms of the category boundary positions,the Vietnamese listeners showed significantly smaller boundary positions than the Mandarin group in the two rising continua,which is because compared with Mandarin Tone 1,the level tone in Vietnamese,i.e.,the ngang tone,has a lower pitch value.However,the Russian listeners showed significantly smaller boundary positions than the Mandarin group in the two falling continua,which is possibly due to the impact of intonation in Russian.As for the category boundary widths,native Mandarin and Vietnamese listeners had significantly narrower boundary widths than Russian listeners.Moreover,the Vietnamese group presented significantly narrower boundary widths for the rising continua than the falling continua.According to the Perceptual Assimilation Model,the rising continua involved two-category assimilation but the falling continua involved uncategorized-categorized assimilation.The discrimination performance for two-category assimilation is predicted to be better than uncategorized-categorized assimilation,which can successfully explain the Vietnamese listeners’ narrower boundary width for the rising continua.With regard to discrimination performances,native Mandarin and Vietnamese listeners showed significantly better between-category discrimination accuracies but significantly worse within-category discrimination accuracies than the Russian listeners in all the four continua,which can be interpreted by the Native Language Magnet Model and the Dual-Process Model.3.Stimulus type also partly accounts for the tone perception performances of these three language groups.On the one hand,the boundary positions of the speech continua consistently occurred at a smaller stimulus number than those of the nonspeech continua.On the other hand,the perception of nonspeech continua was more categorical for Russian listeners than was the perception of speech continua whereas the categorical perception of nonspeech stimuli was comparable to that of speech stimuli for native Mandarin and Vietnamese listeners.These findings can lead to a general conclusion that categorical perception of speech stimuli can be carried over to other nonspeech domains.The above results indicated that categorical perception is domain-general but influenced by L1 categorical representations.To be more specific,in the current study,L1 prosody could constrain the perception of L2 lexical tones.Exploring the impact of L1 background on L2 tone acquisition is very essential for the extension of SLA theories and also for the teaching of L2 tones.