The modification of speech perception and production in second-language learning

The direction of attention in second language phonological contrast learning

This study attempted to describe why some individuals are more successful when learning to perceive the sounds of a second language by analyzing the role attention plays in perceptual learning. Fifty-seven monolingual English-speaking adults completed the study. The participants underwent a perceptual learning paradigm presenting the novel contrast, the voicing contrast between Thai /b/ and /p/. The experiment consisted of a 40-item pretest, 480-trial learning phase, and 40-item posttest. Approximately half of the participants (n = 30) were given explicit instruction to listen for the specific contrast prior to the learning phase; other participants were not told the nature of the contrast. The Attention Network Test (ANT) from Fan, McCandliss, Sommer, Raz, and Posner [(2002). J. Cogn. Neurosci. 14(3), 340-347] was used to assess attentional networks. Generalized linear models and linear mixed effect models (LME) were fit to predict the participants' post-test scores based on ANT subscores, experimental group, and learning block (LME only). The results showed a correlation between attentional control and the ability to learn non-native phoneme contrasts regardless of instruction. In addition, there was a positive interaction between attentional control and the provision of explicit instructions during the learning process, such that individuals with high attentional control learned better when they received explicit instruction prior to training.

Phonetic and Lexical Encoding of Tone in Cantonese Heritage Speakers

Heritage speakers contend with at least two languages: the less dominant first language (L1), that is, the heritage language, and the more dominant second language (L2). In some cases, their L1 and L2 bear striking phonological differences. In the current study, we investigate Toronto-born Cantonese heritage speakers and their maintenance of Cantonese lexical tone, a linguistic feature that is absent from English, the more dominant L2. Across two experiments, Cantonese heritage speakers were tested on their phonetic/phonological and lexical encoding of tone in Cantonese. Experiment 1 was an AX discrimination task with varying inter-stimulus intervals (ISIs), which revealed that heritage speakers discriminated tone pairs with disparate pitch contours better than those with shared pitch contours. Experiment 2 was a medium-term repetition priming experiment, designed to extend the findings of Experiment 1 by examining tone representations at the lexical level. We observed a positive correlation between English dominance and priming in tone minimal pairs that shared contours. Thus, while increased English dominance does not affect heritage speakers' phonological-level representations, tasks that require lexical access suggest that heritage Cantonese speakers may not robustly and fully distinctively encode Cantonese tone in lexical memory.

An analysis of the perception of stop consonants in bilinguals and monolinguals in different phonetic contexts: A range-based language cueing approach

Bilinguals' observed perceptual shift across language contexts for shared acoustic properties between their languages supports the idea that bilinguals, but not monolinguals, develop two phonemic representations for the same acoustic property. This phenomenon is known as the double phonemic boundary. This investigation replicated previous findings of bilinguals' double phonemic boundary across a series of go/no-go tasks while controlling for known confounding effects in speech perception (i.e., contrast effects) and differences in resource allocation between bilinguals and monolinguals (i.e., left-hand or right-hand response). Using a range-base language cueing approach, we designed 2 experiments. The first experiment tested whether a voice onset time (VOT) range representative of either Spanish or English phonetic categories can cue bilinguals, but not monolinguals, to use language-specific perceptual routines. The second experiment tested a VOT range with a mixture of Spanish and English phonetic categories to determine whether directing attention to a specific phonetic category can disambiguate the competition of the nonattended category. The results for Experiment 1 showed that bilinguals can rely on the distributional patterns of their native phonetic categories to activate specific language modes. Experiment 2 showed that attention can change the weight given to a native phonetic distinction. However, this process is restricted by the internal phonetic composition of the native language(s).

Phonetic Category Formation is Perceptually Driven During the Early Stages of Adult L2 Development

Research on the acquisition of L2 phonology in sequential language learners has stressed the importance of language use and input as a means to accurate production and perception; however, the two constructs are difficult to evaluate and control. This study focuses on the role of language use during the initial stages of development of phonetic categories related to stop voicing and analyzes the relationship between production and perception. Native English-speaking late learners of Spanish provided production/perception data on a weekly basis throughout the course of a seven-week immersion program in which L1 use was prohibited. The production/perception data were analyzed using generalized linear mixed effects models. Generalized additive mixed models were used to analyze and compare the learning trajectories of each modality. The analyses revealed phonetic learning in both production and perception over the course of the program. Perception gains paralleled those of native bilinguals by the conclusion of the program and preceded production gains. This study is novel in that it provides production/perception data in a semi-longitudinal design. Moreover, the beginning adult learners are examined in a learning context in which L1 use was minimal and L2 input was maximized. Taken together, the experiments suggest that L2 phonetic category formation can occur abruptly, at an early stage of development, is perceptually driven, and appears to be particularly fragile during the initial stages of learning.

A Bafri, un Pafri

Bilinguals perceptually accommodate speech variation across languages, but to what extent this flexibility depends on bilingual experience is uncertain. One account suggests that bilingual experience promotes language-specific processing modes, implying that bilinguals can switch as appropriate between the different phonetic systems of the languages they speak. Another account suggests that bilinguals rapidly recalibrate to the unique acoustic properties of each language following language-general processes common to monolinguals. Challenging this latter account, the present results show that Spanish-English bilinguals with exposure to both languages from early childhood, but not English monolinguals, shift perception as appropriate across acoustically controlled English and Spanish contexts. Early bilingual experience appears to promote language-specific phonetic systems.

Speakers of tonal and non-tonal Korean dialects use different cue weightings in the perception of the three-way laryngeal stop contrast

The current study investigated the perception of the three-way distinction among Korean voiceless stops in non-tonal Seoul and tonal Kyungsang Korean. The question addressed is whether listeners from these two dialects differ in the way they perceive the three stops. Forty-two Korean listeners (21 each from Seoul and South Kyungsang) were tested in a perception experiment with stimuli in which VOT and F0 were systematically manipulated. Analyses of the perceptual identification functions show that VOT and F0 cues trade off each other for the perception of the three stops. However, the trading relationship differs between the two dialects. Logistic regression analyses confirmed the two dialects use the perceptual cues differently for the lenis and aspirated stops. While Seoul listeners rely primarily on F0 for making lenis responses and on VOT and F0 for aspirated responses, F0 plays a less important role in modulating both lenis and aspirated responses for Kyungsang than for Seoul listeners. It is proposed that different tonal systems between the two dialects and the ongoing diachronic sound change in the stops of Seoul Korean contribute to the inter-dialect difference in cue weighting for the three-way stop distinction. The results suggest that although the difference in phonology between the two dialects influences the phonetic realization, the phonetic trade-off among multiple cues allows each dialect to maintain the phonemic distinction in a unique way.

Discrimination of coronal stops by bilingual adults: the timing and nature of language interaction

The current study was designed to investigate the timing and nature of interaction between the two languages of bilinguals. For this purpose, we compared discrimination of Canadian French and Canadian English coronal stops by simultaneous bilingual, monolingual and advanced early L2 learners of French and English. French /d/ is phonetically described as dental whereas English /d/ is described as alveolar. Using a categorial AXB task, the performance of all four groups was compared to chance and to the performance of native Hindi listeners. Hindi listeners performed well above chance in discriminating French and English /d/-initial syllables. The discrimination performance of advanced early L2 learners, but not simultaneous bilinguals, was consistent with one merged category for coronal stops in the two languages. The data provide evidence for interaction in L2 learners as well as simultaneous bilinguals; however, the nature of the interaction is different in the two groups.

Language-experience facilitates discrimination of /d-/ in monolingual and bilingual acquisition of English

To trace how age and language experience shape the discrimination of native and non-native phonetic contrasts, we compared 4-year-olds learning either English or French or both and simultaneous bilingual adults on their ability to discriminate the English /d-th/ contrast. Findings show that the ability to discriminate the native English contrast improved with age. However, in the absence of experience with this contrast, discrimination of French children and adults remained unchanged during development. Furthermore, although simultaneous bilingual and monolingual English adults were comparable, children exposed to both English and French were poorer at discriminating this contrast when compared to monolingual English-learning 4-year-olds. Thus, language experience facilitates perception of the English /d-th/ contrast and this facilitation occurs later in development when English and French are acquired simultaneously. The difference between bilingual and monolingual acquisition has implications for language organization in children with simultaneous exposure.

Phonological systems in bilinguals: age of learning effects on the stop consonant systems of Korean-English bilinguals

Interaction of Korean and English stop systems in Korean-English bilinguals as a function of age of acquisition (AOA) of English was investigated. It was hypothesized that early bilinguals (mean AOA=3.8 years) would more likely be native-like in production of English and Korean stops and maintain greater independence between Korean and English stop systems than late bilinguals (mean AOA=21.4 years). Production of Korean and English stops was analyzed in terms of three acoustic-phonetic properties: voice-onset time, amplitude difference between the first two harmonics, and fundamental frequency. Late bilinguals were different from English monolinguals for English voiceless and voiced stops in all three properties. As for Korean stops, late bilinguals were different from Korean monolinguals for fortis stops in voice-onset time. Early bilinguals were not different from the monolinguals of either language. Considering the independence of the two stop systems, late bilinguals seem to have merged English voiceless and Korean aspirated stops and produced English voiced stops with similarities to both Korean fortis and lenis stops, whereas early bilinguals produced five distinct stop types. Thus, the early bilinguals seem to have two independent stop systems, whereas the late bilinguals likely have a merged Korean-English system.

The vowel systems of Quichua-Spanish bilinguals. Age of acquisition effects on the mutual influence of the first and second languages

This study investigates vowel productions of 20 Quichua-Spanish bilinguals, differing in age of Spanish acquisition, and 5 monolingual Spanish speakers. While the vowel systems of simultaneous, early, and some mid bilinguals all showed significant plasticity, there were important differences in the kind, as well as the extent, of this adaptability. Simultaneous bilinguals differed from early bilinguals in that they were able to partition the vowel space in a more fine-grained way to accommodate the vowels of their two languages. Early and some mid bilinguals acquired Spanish vowels, whereas late bilinguals did not. It was also found that acquiring Spanish vowels could affect the production of native Quichua vowels. The Quichua vowels were produced higher by bilinguals who had acquired Spanish vowels than those who had not. It is proposed that this vowel reorganization serves to enhance the perceptual distinctiveness between the vowels of the combined first- and second-language system.

Holding on to childhood language memory

While early language experience seems crucial for mastering phonology, it remains unclear whether there are lasting benefits of speaking a language regularly during childhood if the quantity and quality of speaking drop dramatically after childhood. This study explored the accessibility of early childhood language memory. Specifically, it compared perception and production of Korean speech sounds by childhood speakers who had spoken Korean regularly for a few years during childhood to those of two other groups: (1) childhood hearers who had heard Korean regularly during childhood but had spoken Korean minimally, if at all; and (2) novice learners. All three groups were enrolled in first-year college Korean language classes. Childhood speakers were also compared to native speakers of Korean to see how native-like they were. The results revealed measurable long-term benefits of childhood speaking experience, underscoring the importance of early language experience, even if such experience diminishes dramatically beyond childhood.

Overhearing a language during childhood

Despite its significance for understanding of language acquisition, the role of childhood language experience has been examined only in linguistic deprivation studies focusing on what cannot be learned readily beyond childhood. This study focused instead on long-term effects of what can be learned best during childhood. Our findings revealed that adults learning a language speak with a more native like accent if they overheard the language regularly during childhood than if they did not. These findings have important implications for understanding of language-learning mechanisms and heritage-language acquisition.

Category restructuring during second-language speech acquisition

This study examined the production of English /b/ and the perception of short-lag English /b d g/ tokens by four groups of bilinguals who differed according to their age of arrival (AOA) in Canada from Italy and amount of self-reported native language (L1) use. A clear difference emerged between early bilinguals (mean AOA= 8 years) and late bilinguals (mean AOA= 20 years). The late bilinguals showed a stronger L1 influence than the early bilinguals did on both the production and perception of English stops. In experiment 2, the late bilinguals produced a larger percentage of prevoiced English /b/ tokens than early bilinguals and native English (NE) speakers did. In experiment 3, the late bilinguals misidentified short-lag English /b d g/ tokens as /p t k/ more often than the early bilinguals and NE speakers did. Experiment 4 revealed that the frequencies with which the bilinguals prevoiced /b d g/ in Italian and English were correlated. The observed differences between the early and late bilinguals were attributed to differences in the quantity and quality of English phonetic input they had received, not to a greater likelihood by the early than late bilinguals to establish new phonetic categories for English /b d g/.

Age of second-language acquisition and perception of speech in noise

To determine how age of acquisition influences perception of second-language speech, the Speech Perception in Noise (SPIN) test was administered to native Mexican-Spanish-speaking listeners who learned fluent English before age 6 (early bilinguals) or after age 14 (late bilinguals) and monolingual American-English speakers (monolinguals). Results show that the levels of noise at which the speech was intelligible were significantly higher and the benefit from context was significantly greater for monolinguals and early bilinguals than for late bilinguals. These findings indicate that learning a second language at an early age is important for the acquisition of efficient high-level processing of it, at least in the presence of noise.

The development of English speech patterns of a 7-year-old Polish-speaking child

The silent period hypothesis was investigated by examining the speech development of AO, a Polish-speaking child, who emigrated to the U.S. at age 7 years, 5 months, and placed in the second grade of a rural Missouri school district in which there was no instruction of English as a second-language. AO was observed for 6 years, 8 months, in order to study the development of his English speech patterns. During this interval, recordings were made of five sentences produced by AO at five different age points and with recordings from a control group of native and nonnative speakers were rated by native American speakers. AO's accent showed a gradual decline during the first year of residence, receiving a rating of near-native speech. By age 14 years, 6 months, he was rated as having native speech performance. Observations of his language, social, and school development indicated that AO remained essentially silent during the first 6 months, using two- and three-word sentences only when necessary, that his social development was normal, and that his school achievement was not impeded by his placement in the grade level appropriate for his age. The conclusion was reached that AO's silent period experience contributed significantly to his development of English speech patterns.

Consonant and vowel perception and production: early English-French bilinguals and English monolinguals

This study is a comparative analysis of the English phonetic systems of 10 fluent adult English-French bilinguals who acquired their two languages prior to age 8 and who were English-dominant, and of 10 adult English monolinguals. The objective of the study was to determine whether or not early English-dominant bilinguals perceive and produce speech as English monolinguals do. Discrimination and identification tests of synthetic (d-t) and (i-I) continua and speech production tests revealed that the bilinguals' discrimination and production of (d) and (t) and their production of (I) did not differ significantly from the monolinguals'. However, the bilinguals' identification of (d-t) and (i-I) and one aspect of their production of (i) did differ significantly from that of the monolinguals. The present results indicate that early bilingualism can yield monolingual-like performance in at least one of the bilinguals' languages, but only with respect to certain aspects of the phonetic system. These findings are viewed in light of sound-class distinctions, the perception-production dichotomy, and bilingual phonetic transfer and restructuring.