A New View of Language Development: The Acquisition of Lexical Tone

Acoustic characteristics of infant- and foreigner-directed speech with Mandarin as the target language

The quality of speech input influences the efficiency of L1 and L2 acquisition. This study examined modifications in infant-directed speech (IDS) and foreigner-directed speech (FDS) in Standard Mandarin-a tonal language-and explored how IDS and FDS features were manifested in disyllabic words and a longer discourse. The study aimed to determine which characteristics of IDS and FDS were enhanced in comparison with adult-directed speech (ADS), and how IDS and FDS differed when measured in a common set of acoustic parameters. For words, it was found that tone-bearing vowel duration, mean and range of fundamental frequency (F0), and the lexical tone contours were enhanced in IDS and FDS relative to ADS, except for the dipping Tone 3 that exhibited an unexpected lowering in FDS, but no modification in IDS when compared with ADS. For the discourse, different aspects of temporal and F0 enhancements were emphasized in IDS and FDS: the mean F0 was higher in IDS whereas the total discourse duration was greater in FDS. These findings add to the growing literature on L1 and L2 speech input characteristics and their role in language acquisition.

The development of tone discrimination in infancy: Evidence from a cross-linguistic, multi-lab report

We report the findings of a multi-language and multi-lab investigation of young infants' ability to discriminate lexical tones as a function of their native language, age and language experience, as well as of tone properties. Given the high prevalence of lexical tones across human languages, understanding lexical tone acquisition is fundamental for comprehensive theories of language learning. While there are some similarities between the developmental course of lexical tone perception and that of vowels and consonants, findings for lexical tones tend to vary greatly across different laboratories. To reconcile these differences and to assess the developmental trajectory of native and non-native perception of tone contrasts, this study employed a single experimental paradigm with the same two pairs of Cantonese tone contrasts (perceptually similar vs. distinct) across 13 laboratories in Asia-Pacific, Europe and North-America testing 5-, 10- and 17-month-old monolingual (tone, pitch-accent, non-tone) and bilingual (tone/non-tone, non-tone/non-tone) infants. Across the age range and language backgrounds, infants who were not exposed to Cantonese showed robust discrimination of the two non-native lexical tone contrasts. Contrary to this overall finding, the statistical model assessing native discrimination by Cantonese-learning infants failed to yield significant effects. These findings indicate that lexical tone sensitivity is maintained from 5 to 17 months in infants acquiring tone and non-tone languages, challenging the generalisability of the existing theoretical accounts of perceptual narrowing in the first months of life. RESEARCH HIGHLIGHTS: This is a multi-language and multi-lab investigation of young infants' ability to discriminate lexical tones. This study included data from 13 laboratories testing 5-, 10-, and 17-month-old monolingual (tone, pitch-accent, non-tone) and bilingual (tone/non-tone, non-tone/non-tone) infants. Overall, infants discriminated a perceptually similar and a distinct non-native tone contrast, although there was no evidence of a native tone-language advantage in discrimination. These results demonstrate maintenance of tone discrimination throughout development.

Investigating Perception to Production Transfer in Children With Cochlear Implants: A High Variability Phonetic Training Study

PURPOSE

This study builds upon an established effective training method to investigate the advantages of high variability phonetic identification training for enhancing lexical tone perception and production in Mandarin-speaking pediatric cochlear implant (CI) recipients, who typically face ongoing challenges in these areas.

METHOD

Thirty-two Mandarin-speaking children with CIs were quasirandomly assigned into the training group (TG) and the control group (CG). The 16 TG participants received five sessions of high variability phonetic training (HVPT) within a period of 3 weeks. The CG participants did not receive the training. Perception and production of Mandarin tones were administered before (pretest) and immediately after (posttest) the completion of HVPT via lexical tone recognition task and picture naming task. Both groups participated in the identical pretest and posttest with the same time frame between the two test sessions.

RESULTS

TG showed significant improvement from pretest to posttest in identifying Mandarin tones for both trained and untrained speech stimuli. Moreover, perceptual learning of HVPT significantly facilitated trainees' production of T1 and T2 as rated by a cohort of 10 Mandarin-speaking adults with normal hearing, which was corroborated by acoustic analyses revealing improved fundamental frequency (F0) median for T1 and T2 production and enlarged F0 movement for T2 production. In contrast, TG children's production of T3 and T4 showed nonsignificant changes across two test sessions. Meanwhile, CG did not exhibit significant changes in either perception or production.

CONCLUSIONS

The results suggest a limited and inconsistent transfer of perceptual learning to lexical tone production in children with CIs, which challenges the notion of a robust transfer and highlights the complexity of the interaction between perceptual training and production outcomes. Further research on individual differences with a longitudinal design is needed to optimize the training protocol or tailor interventions to better meet the diverse needs of learners.

Cortical specialization associated with native speech category acquisition in early infancy

This study investigates neural processes in infant speech processing, with a focus on left frontal brain regions and hemispheric lateralization in Mandarin-speaking infants' acquisition of native tonal categories. We tested 2- to 6-month-old Mandarin learners to explore age-related improvements in tone discrimination, the role of inferior frontal regions in abstract speech category representation, and left hemisphere lateralization during tone processing. Using a block design, we presented four Mandarin tones via [ta] and measured oxygenated hemoglobin concentration with functional near-infrared spectroscopy. Results showed age-related improvements in tone discrimination, greater involvement of frontal regions in older infants indicating abstract tonal representation development and increased bilateral activation mirroring native adult Mandarin speakers. These findings contribute to our broader understanding of the relationship between native speech acquisition and infant brain development during the critical period of early language learning.

Playing With Fire Compounds: The Tonal Accents of Compounds in (North) Norwegian Preschoolers' Role-Play Register

Prosodic features are some of the most salient features of dialect variation in Norway. It is therefore no wonder that the switch in prosodic systems is what is first recognized by caretakers and scholars when Norwegian children code-switch to something resembling the dialect of the capital (henceforth Urban East Norwegian, UEN) in role-play. With a focus on the system of lexical tonal accents, this paper investigates the spontaneous speech of North Norwegian children engaging in peer social role-play. By investigating F0 contours extracted from a corpus of spontaneous peer play, and comparing them with elicited baseline reference contours, this paper makes the case that children fail to apply the target tonal accent consistent with UEN in compounds in role-play, although the production of tonal accents otherwise seems to be phonetically target like UEN. Put in other words, they perform in accordance with UEN phonetics, but not UEN morpho-phonology.

Acquisition of Mandarin tones by Canadian first graders: Effect of prior exposure to tonal and non-tonal languages

This study examines the tone productions of school-aged children with and without a tonal language background who are learning Mandarin as a second language (L2) or heritage language in Mandarin-English bilingual schools in Western Canada. Tones are frequently identified as one of the most challenging aspects of phonology for Mandarin L2 learners to acquire. In this study, tone productions of bilingual children from three home language backgrounds, English, Cantonese, and Mandarin Chinese, were compared for transcribed accuracy using mixed effects logistic regression. In addition, the fundamental frequency contours of correct tone productions were fitted with generalized additive mixed models to analyse the acoustic differences between groups. Error patterns were also analysed for possible Cantonese substitutions. Our results suggest that children with a Cantonese background are more accurate in tone productions than children with an English language background, but they also made more errors than their peers with a Mandarin language background. These findings suggest that a tonal language background could result in positive transfer among school-age children who are in the early stages of learning Mandarin as an L2.

Why Aren't All Cantonese Tones Equally Confusing to English Listeners?

English listeners often struggle to perceive tones, but some are easier than others. This study examined these phenomena grounded in the feature weighing perspective (FWP) and the Perceptual Assimilation Model for Suprasegmentals (PAM-S). Forty-seven English and Cantonese listeners completed 4,212 trials of Cantonese tone discrimination and sequence recall tasks. The English listeners showed asymmetrical perceptual patterns of discrimination but not sequence recall. Specifically, these English listeners discriminated T1-T5, T3-T5, and T4-T5 more accurately than T1-T4, T3-T4, and T1-T3. However, they recalled the contour tone and level tone sequences with similar accuracies. Results of the discrimination task aligned with the predictions of PAM-S but not FWP. However, results of the sequence recall task did not support PAM-S. Together, these results suggest that PAM-S only applies to simple discrimination, not abstract phonological processing with a high memory load.

Lexical tone perception and learning in older adults: A review and future directions

While the literature is well represented in accounting for how aging influences segmental properties of speech, less is known about its influences on suprasegmental properties such as lexical tones. In addition, foreign language learning is increasingly endorsed as being a potential intervention to boost cognitive reserve and overall well-being in older adults. Empirical studies on young learners learning lexical tones are aplenty in comparison with older learners. Challenges in this domain for older learners might be different due to aging and other learner-internal factors. This review consolidates behavioural and neuroscientific research related to lexical tone, speech perception, factors characterising learner groups, and other variables that would influence lexical tone perception and learning in older adults. Factors commonly identified to influence tone learning in younger adult populations, such as musical experience, language background, and motivation in learning a new language, are discussed in relation to older learner groups and recommendations to boost lexical tone learning in older age are provided based on existing studies.

Evaluating the Relative Perceptual Salience of Linguistic and Emotional Prosody in Quiet and Noisy Contexts

How people recognize linguistic and emotional prosody in different listening conditions is essential for understanding the complex interplay between social context, cognition, and communication. The perception of both lexical tones and emotional prosody depends on prosodic features including pitch, intensity, duration, and voice quality. However, it is unclear which aspect of prosody is perceptually more salient and resistant to noise. This study aimed to investigate the relative perceptual salience of emotional prosody and lexical tone recognition in quiet and in the presence of multi-talker babble noise. Forty young adults randomly sampled from a pool of native Mandarin Chinese with normal hearing listened to monosyllables either with or without background babble noise and completed two identification tasks, one for emotion recognition and the other for lexical tone recognition. Accuracy and speed were recorded and analyzed using generalized linear mixed-effects models. Compared with emotional prosody, lexical tones were more perceptually salient in multi-talker babble noise. Native Mandarin Chinese participants identified lexical tones more accurately and quickly than vocal emotions at the same signal-to-noise ratio. Acoustic and cognitive dissimilarities between linguistic prosody and emotional prosody may have led to the phenomenon, which calls for further explorations into the underlying psychobiological and neurophysiological mechanisms.

Implicit Association Test (IAT) Studies Investigating Pitch-Shape Audiovisual Cross-modal Associations Across Language Groups

Previous studies have shown that Chinese speakers and non-Chinese speakers exhibit different patterns of cross-modal congruence for the lexical tones of Mandarin Chinese, depending on which features of the pitch they attend to. But is this pattern of language-specific listening a conscious cultural strategy or an automatic processing effect? If automatic, does it also apply when the same pitch contours no longer sound like speech? Implicit Association Tests (IATs) provide an indirect measure of cross-modal association. In a series of IAT studies, conducted with participants with three kinds of language backgrounds (Chinese-dominant bilinguals, Chinese balanced bilinguals, and English speakers with no Chinese experience) we find language-specific congruence effects for Mandarin lexical tones but not for matched sine-wave stimuli. That is, for linguistic stimuli, non-Chinese speakers show advantages for pitch-height congruence (high-pointy, low-curvy); no congruence effects were found for Chinese speakers. For non-linguistic stimuli, all participant groups showed advantages for pitch-height congruence. The present findings suggest that non-lexical tone congruence (high-pointy, low-curvy) is a basic congruence pattern, and the acquisition of a language with lexical tone can alter this perception.

Lexical and Prosodic Pitch Modifications in Cantonese Infant-directed Speech

The functions of acoustic-phonetic modifications in infant-directed speech (IDS) remain a question: do they specifically serve to facilitate language learning via enhanced phonemic contrasts (the hyperarticulation hypothesis) or primarily to improve communication via prosodic exaggeration (the prosodic hypothesis)? The study of lexical tones provides a unique opportunity to shed light on this, as lexical tones are phonemically contrastive, yet their primary cue, pitch, is also a prosodic cue. This study investigated Cantonese IDS and found increased intra-talker variation of lexical tones, which more likely posed a challenge to rather than facilitated phonetic learning. Although tonal space was expanded which could facilitate phonetic learning, its expansion was a function of overall intonational modifications. Similar findings were observed in speech to pets who should not benefit from larger phonemic distinction. We conclude that lexical-tone adjustments in IDS mainly serve to broadly enhance communication rather than specifically increase phonemic contrast for learners.

Perceptual narrowing in face- and speech-perception domains in infancy: A longitudinal approach

During the first year of life, infants undergo a process known as perceptual narrowing, which reduces their sensitivity to classes of stimuli which the infants do not encounter in their environment. It has been proposed that perceptual narrowing for faces and speech may be driven by shared domain-general processes. To investigate this theory, our study longitudinally tested 50 German Caucasian infants with respect to these domains first at 6 months of age followed by a second testing at 9 months of age. We used an infant-controlled habituation-dishabituation paradigm to test the infants' ability to discriminate among other-race Asian faces and non-native Cantonese speech tones, as well as same-race Caucasian faces as a control. We found that while at 6 months of age infants could discriminate among all stimuli, by 9 months of age they could no longer discriminate among other-race faces or non-native tones. However, infants could discriminate among same-race stimuli both at 6 and at 9 months of age. These results demonstrate that the same infants undergo perceptual narrowing for both other-race faces and non-native speech tones between the ages of 6 and 9 months. This parallel development of perceptual narrowing occurring in both the face and speech perception modalities over the same period of time lends support to the domain-general theory of perceptual narrowing in face and speech perception.

Lifelong Tone Language Experience does not Eliminate Deficits in Neural Encoding of Pitch in Autism Spectrum Disorder

Atypical pitch processing is a feature of Autism Spectrum Disorder (ASD), which affects non-tone language speakers' communication. Lifelong auditory experience has been demonstrated to modify genetically-predisposed risks for pitch processing. We examined individuals with ASD to test the hypothesis that lifelong auditory experience in tone language may eliminate impaired pitch processing in ASD. We examined children's and adults' Frequency-following Response (FFR), a neurophysiological component indexing early neural sensory encoding of pitch. Univariate and machine-learning-based analytics suggest less robust pitch encoding and diminished pitch distinctions in the FFR from individuals with ASD. Contrary to our hypothesis, results point to a linguistic pitch encoding impairment associated with ASD that may not be eliminated even by lifelong sensory experience.

The Influence of Tonal and Atonal Bilingualism on Children's Lexical and Non-Lexical Tone Perception

This study examined how bilingualism in an atonal language, in addition to a tonal language, influences lexical and non-lexical tone perception and word learning during childhood. Forty children aged 5;3-7;2, bilingual either in English and Mandarin or English and another atonal language, were tested on Mandarin lexical tone discrimination, level-pitch sine-wave tone discrimination, and learning of novel words differing minimally in Mandarin lexical tone. Mandarin-English bilingual children discriminated between and learned novel words differing minimally in Mandarin lexical tone more accurately than their atonal-English bilingual peers. However, Mandarin-English and atonal-English bilingual children discriminated between level-pitch sine-wave tones with similar accuracy. Moreover, atonal-English bilingual children showed a tendency to perceive differing Mandarin lexical and level-pitch sine-wave tones as identical, whereas their Mandarin-English peers showed no such tendency. These results indicate that bilingualism in a tonal language in addition to an atonal language-but not bilingualism in two atonal languages-allows for continued sensitivity to lexical tone beyond infancy. Moreover, they suggest that although tonal-atonal bilingualism does not enhance sensitivity to differences in pitch between sine-wave tones beyond infancy any more effectively than atonal-atonal bilingualism, it protects against the development of biases to perceive differing lexical and non-lexical tones as identical. Together, the results indicate that, beyond infancy, tonal-atonal bilinguals process lexical tones using different cognitive mechanisms than atonal-atonal bilinguals, but that both groups process level-pitch non-lexical tone using the same cognitive mechanisms.

Development of Phonetic Contrasts in Cantonese Tone Acquisition

Purpose Previous studies showed both early and late acquisition of Cantonese tones based on transcription data using different criteria, but very little acoustic data were reported. Our study examined Cantonese tone acquisition using both transcription and acoustic data, illustrating the early and protracted aspects of Cantonese tone acquisition. Method One hundred fifty-nine Cantonese-speaking children aged between 2;1 and 6;0 (years;months) and 10 reference speakers participated in a tone production experiment based on picture naming. Natural production materials with 30 monosyllabic words were transcribed by two native judges. Acoustic measurements included overall tonal dispersion and specific contrasts between similar tone pairs: ratios of average fundamental frequency height for the level tones (T1, T3, T6), magnitude of rise and inflection point for the rising tones (T2, T5), magnitude of fall, H1*-H2*, and harmonic-to-noise ratio for the low tones (T4, T6). Auditory assessment of creakiness for T4 was also included. Results Children in the eldest group (aged 5;7-6;0) were still not completely adultlike in production accuracy, although two thirds of them had production accuracy over 90%. Children in all age groups had production accuracy significantly higher than chance level, and they could produce the major acoustic contrasts between specific tone pairs similarly as reference speakers. Fine phonetic detail of the inflection point and creakiness was more challenging for children. Conclusion Our findings illustrated the multifaceted aspects (both early and late) of Cantonese tone acquisition and called for a wider perspective on how to define successful phonological acquisition. Supplemental Material https://doi.org/10.23641/asha.11594853.

Age-sensitive associations of segmental and suprasegmental perception with sentence-level language skills in Mandarin-speaking children with cochlear implants

BACKGROUND AND AIM

It remains unclear how recognition of segmental and suprasegmental phonemes contributes to sentence-level language processing skills in Mandarin-speaking children with cochlear implants (CIs). Our study examined the influence of implantation age on the recognition of consonants, lexical tones and sentences respectively, and more importantly, the contribution of phonological skills to sentence repetition accuracy in Mandarin-speaking children with CIs.

METHODS

The participants were three groups of prelingually deaf children who received cochlear implants at various ages and their age-matched controls with normal hearing. Three tasks were administered to assess their consonant perception, lexical tone recognition and language skills in open-set sentence repetition.

RESULTS

Children with CIs lagged behind NH peers in all the three tests, and performances on segmental, suprasegmental and sentence-level processing were differentially modulated by implantation age. Furthermore, performances on recognition of consonants and lexical tones were significant predictors of sentence repetition accuracy in the children with CIs.

CONCLUSION

Overall, segmental and suprasegmental perception as well as sentence-level processing is impaired in Mandarin-speaking children with CIs compared with age-matched children with NH. In children with CIs recognition of segmental and suprasegmental phonemes at the lower level predicts sentence repetition accuracy at the higher level. More importantly, implantation age plays an important role in the development of phonological skills and higher-order language skills, suggesting that age-appropriate aural rehabilitation and speech intervention programs need to be developed in order to better help CI users who receive CIs at different ages.

Protracted Development on Native Tone Interpretation: Evidence From Mandarin-Learning Infants' Novel Word Learning

Studies have shown that infants from cultures with tone languages develop categorical perception of their native lexical tone before their first birthday, but few studies have explored whether, and when, they interpret the phonemic function of lexical tone in word learning. Two habituation-switch experiments were conducted to explore whether Mandarin-learning infants could exploit tonal cues during their word learning, and detect a change when the association of two word-object pairs was switched. In Experiment 1, two words were solely differentiated by their lexical tones (/fāi/ vs. /făi/), and Mandarin-learning infants failed to detect the switch of tones at 14 months, but succeeded at 18 months. In Experiment 2, two words were markedly distinct (/fāi/ vs. /bǒu/), and infants could detect the change of words as early as 14 months. The results indicate that infants may not refer to the lexical function of tone during their novel word learning until 18 months, even though infants from birth are able to distinguish the Tone 1 vs. Tone 3 contrast. Given that lexical tone is expressed by variations of the pitch contours, which are also related to intonation, infants’ increasing knowledge of both tone and intonation may contribute to their misinterpretation of pitch contours in word learning at 14 months and, further, to their development of a sophisticated use of the phonemic function of lexical tone at 18 months of age.

Nonword repetition stimuli for Vietnamese-speaking children

Nonword repetition (NWR) has been a widely used measure of language-learning ability in children with and without language disorders. Although NWR tasks have been created for a variety of languages, minimal attention has been given to Asian tonal languages. This study introduces a new set of NWR stimuli for Vietnamese. The stimuli include 20 items ranging in length from one to four syllables. The items consist of dialect-neutral phonemes in consonant-vowel (CV) and CVC sequences that follow the phonotactic constraints of the language. They were rated high on wordlikeness and have comparable position segments and biphone probabilities across stimulus lengths. We validated the stimuli with a sample of 59 typically developing Vietnamese-English bilingual children, ages 5 to 8. The stimuli exhibited the expected age and length effects commonly found in NWR tasks: Older children performed better on the task than younger children, and longer items were more difficult to repeat than shorter items. We also compared different scoring systems in order to examine the individual phoneme types (consonants, vowels, and tones) and composite scores (proportions of phonemes correct, with and without tone). The study demonstrates careful construction and validation of the stimuli, and future directions are discussed.

Assessing the Link Between Perception and Production in Cantonese Tone Acquisition

Purpose Previous studies showed early production precedes late perception in Cantonese tone acquisition, contrary to the general principle that perception precedes production in child language. How tone production and perception are linked in 1st language acquisition remains largely unknown. Our study revisited the acquisition of tone in Cantonese-speaking children, exploring the possible link between production and perception in 1st language acquisition. Method One hundred eleven Cantonese-speaking children aged between 2;0 and 6;0 (years;months) and 10 adolescent reference speakers participated in tone production and perception experiments. Production materials with 30 monosyllabic words were transcribed in filtered and unfiltered conditions by 2 native judges. Perception accuracy was based on a 2-alternative forced-choice task with pictures covering all possible tone pair contrasts. Results Children's accuracy of production and perception of all the 6 Cantonese tones was still not adultlike by age 6;0. Both production and perception accuracies matured with age. A weak positive link was found between the 2 accuracies. Mother's native language contributed to children's production accuracy. Conclusions Our findings show that production and perception abilities are associated in tone acquisition. Further study is needed to explore factors affecting production accuracy in children. Supplemental Material https://doi.org/10.23641/asha.7960826.

The Use of Pitch Accent in Word-Object Association by Monolingual Japanese Infants

This study investigated the lexical use of Japanese pitch accent in Japanese-learning infants. A word-object association task revealed that 18-month-old infants succeeded in learning the associations between two nonsense objects paired with two nonsense words minimally distinguished by pitch pattern (Experiment 1). In contrast, 14-month-old infants failed (Experiment 2). Eighteen-month-old infants succeeded even for sounds that contained only the prosodic information (Experiment 3). However, a subsequent experiment revealed that 14-month-old infants succeeded in an easier single word-object task using pitch contrast (Experiment 4). These findings indicate that pitch pattern information is robustly available to 18-month-old Japanese monolingual infants in a minimal pair word-learning situation, but only partially accessible in the same context for 14-month-old infants.

Perceptual Reorganization of Lexical Tones: Effects of Age and Experimental Procedure

Findings on the perceptual reorganization of lexical tones are mixed. Some studies report good tone discrimination abilities for all tested age groups, others report decreased or enhanced discrimination with increasing age, and still others report U-shaped developmental curves. Since prior studies have used a wide range of contrasts and experimental procedures, it is unclear how specific task requirements interact with discrimination abilities at different ages. In the present work, we tested German and Cantonese adults on their discrimination of Cantonese lexical tones, as well as German-learning infants between 6 and 18 months of age on their discrimination of two specific Cantonese tones using two different types of experimental procedures. The adult experiment showed that German native speakers can discriminate between lexical tones, but native Cantonese speakers show significantly better performance. The results from German-learning infants suggest that 6- and 18-month-olds discriminate tones, while 9-month-olds do not, supporting a U-shaped developmental curve. Furthermore, our results revealed an effect of methodology, with good discrimination performance at 6 months after habituation but not after familiarization. These results support three main conclusions. First, habituation can be a more sensitive procedure for measuring infants' discrimination than familiarization. Second, the previous finding of a U-shaped curve in the discrimination of lexical tones is further supported. Third, discrimination abilities at 18 months appear to reflect mature perceptual sensitivity to lexical tones, since German adults also discriminated the lexical tones with high accuracy.

Lexical Tones in Mandarin Chinese Infant-Directed Speech: Age-Related Changes in the Second Year of Life

Tonal information is essential to early word learning in tone languages. Although numerous studies have investigated the intonational and segmental properties of infant-directed speech (IDS), only a few studies have explored the properties of lexical tones in IDS. These studies mostly focused on the first year of life; thus little is known about how lexical tones in IDS change as children's vocabulary acquisition accelerates in the second year (Goldfield and Reznick, 1990; Bloom, 2001). The present study examines whether Mandarin Chinese mothers hyperarticulate lexical tones in IDS addressing 18- and 24-month-old children-at which age children are learning words at a rapid speed-vs. adult-directed speech (ADS). Thirty-nine Mandarin Chinese-speaking mothers were tested in a semi-spontaneous picture-book-reading task, in which they told the same story to their child (IDS condition) and to an adult (ADS condition). Results for the F0 measurements (minimum F0, maximum F0, and F0 range) of tone in the speech data revealed a continuum of differences among IDS addressing 18-month-olds, IDS addressing 24-month-olds, and ADS. Lexical tones in IDS addressing 18-month-old children had a higher minimum F0, higher maximum F0, and larger pitch range than lexical tones in ADS. Lexical tones in IDS addressing 24-month-old children showed more similarity to ADS tones with respect to pitch height: there were no differences in minimum F0 and maximum F0 between ADS and IDS. However, F0 range was still larger. These results suggest that lexical tones are generally hyperarticulated in Mandarin Chinese IDS addressing 18- and 24- month-old children despite the change in pitch level over time. Mandarin Chinese mothers hyperarticulate lexical tones in IDS when talking to toddlers and potentially facilitate tone acquisition and word learning.

No perceptual reorganization for Limburgian tones? A cross-linguistic investigation with 6- to 12-month-old infants

Despite the fact that many of the world's languages use lexical tone, the majority of language acquisition studies has focused on non-tone languages. Research on tone languages has typically investigated well-known tone languages such as Mandarin and Cantonese Chinese. The current study looked at a Limburgian dialect of Dutch that uses lexical pitch differences, albeit in a rather restricted way. Using a visual habituation paradigm, 6- to 12-month-old Limburgian and Dutch infants were tested for their ability to discriminate Limburgian tones. The results showed that both Limburgian and Dutch infants discriminate the Limburgian tones throughout their first year of life. The role of linguistic experience, acoustic salience, and the degree of similarity to the native prosodic system are discussed.

The Effects of Lexical Pitch Accent on Infant Word Recognition in Japanese

Learners of lexical tone languages (e.g., Mandarin) develop sensitivity to tonal contrasts and recognize pitch-matched, but not pitch-mismatched, familiar words by 11 months. Learners of non-tone languages (e.g., English) also show a tendency to treat pitch patterns as lexically contrastive up to about 18 months. In this study, we examined if this early-developing capacity to lexically encode pitch variations enables infants to acquire a pitch accent system, in which pitch-based lexical contrasts are obscured by the interaction of lexical and non-lexical (i.e., intonational) features. Eighteen 17-month-olds learning Tokyo Japanese were tested on their recognition of familiar words with the expected pitch or the lexically opposite pitch pattern. In early trials, infants were faster in shifting their eyegaze from the distractor object to the target object than in shifting from the target to distractor in the pitch-matched condition. In later trials, however, infants showed faster distractor-to-target than target-to-distractor shifts in both the pitch-matched and pitch-mismatched conditions. We interpret these results to mean that, in a pitch-accent system, the ability to use pitch variations to recognize words is still in a nascent state at 17 months.

Is a High Tone Pointy? Speakers of Different Languages Match Mandarin Chinese Tones to Visual Shapes Differently

Studies investigating cross-modal correspondences between auditory pitch and visual shapes have shown children and adults consistently match high pitch to pointy shapes and low pitch to curvy shapes, yet no studies have investigated linguistic-uses of pitch. In the present study, we used a bouba/kiki style task to investigate the sound/shape mappings for Tones of Mandarin Chinese, for three groups of participants with different language backgrounds. We recorded the vowels [i] and [u] articulated in each of the four tones of Mandarin Chinese. In Study 1 a single auditory stimulus was presented with two images (one curvy, one spiky). In Study 2 a single image was presented with two auditory stimuli differing only in tone. Participants were asked to select the best match in an online ‘Quiz.’ Across both studies, we replicated the previously observed ‘u-curvy, i-pointy’ sound/shape cross-modal correspondence in all groups. However, Tones were mapped differently by people with different language backgrounds: speakers of Mandarin Chinese classified as Chinese-dominant systematically matched Tone 1 (high, steady) to the curvy shape and Tone 4 (falling) to the pointy shape, while English speakers with no knowledge of Chinese preferred to match Tone 1 (high, steady) to the pointy shape and Tone 3 (low, dipping) to the curvy shape. These effects were observed most clearly in Study 2 where tone-pairs were contrasted explicitly. These findings are in line with the dominant patterns of linguistic pitch perception for speakers of these languages (pitch-change, and pitch height, respectively). Chinese English balanced bilinguals showed a bivalent pattern, swapping between the Chinese pitch-change pattern and the English pitch-height pattern depending on the task. These findings show for that the supposedly universal pattern of mapping linguistic sounds to shape is modulated by the sensory properties of a speaker’s language system, and that people with high functioning in more than one language can dynamically shift between patterns.

How Native Prosody Affects Pitch Processing during Word Learning in Limburgian and Dutch Toddlers and Adults

In this study, Limburgian and Dutch 2.5- to 4-year-olds and adults took part in a word learning experiment. Following the procedure employed by Quam and Swingley (2010) and Singh et al. (2014), participants learned two novel word-object mappings. After training, word recognition was tested in correct pronunciation (CP) trials and mispronunciation (MP) trials featuring a pitch change. Since Limburgian is considered a restricted tone language, we expected that the pitch change would hinder word recognition in Limburgian, but not in non-tonal Dutch listeners. Contrary to our expectations, both Limburgian and Dutch children appeared to be sensitive to pitch changes in newly learned words, indicated by a significant decrease in target fixation in MP trials compared to CP trials. Limburgian and Dutch adults showed very strong naming effects in both trial types. The results are discussed against the background of the influence of the native prosodic system.

Cantonese-Speaking Children Do Not Acquire Tone Perception before Tone Production-A Perceptual and Acoustic Study of Three-Year-Olds' Monosyllabic Tones

Models of phonological development assume that speech perception precedes speech production and that children acquire suprasegmental features earlier than segmental features. Studies of Chinese-speaking children challenge these assumptions. For example, Chinese-speaking children can produce tones before two-and-a-half years but are not able to discriminate the same tones until after 6 years of age. This study compared the perception and production of monosyllabic Cantonese tones directly in 3 -year-old children. Twenty children and their mothers identified Cantonese tones in a picture identification test and produced monosyllabic tones in a picture labeling task. To control for lexical biases on tone ratings, the mother- and child-productions were low-pass filtered to eliminate lexical information and were presented to five judges for tone classification. Detailed acoustic analysis was performed. Contrary to the view that children master lexical tones earlier than segmental phonemes, results showed that 3-year-old children could not perceive or produce any Cantonese tone with adult-like proficiency and incorrect tone productions were acoustically different from criterion. In contrast to previous findings that Cantonese-speaking children mastered tone production before tone perception, we observed more accuracy during speech perception than production. Findings from Cantonese-speaking children challenge some of the established tenets in theories of phonological development that have been tested mostly with native English speakers.

Phonetic complexity affects children's Mandarin tone production accuracy in disyllabic words: A perceptual study

This is the first study to examine the effect of phonetic contexts on children's lexical tone production. Mandarin tones in disyllabic words produced by forty-four 2- to 6-year-old children and twelve mothers were low-pass filtered to eliminate lexical information. Native Mandarin-speaking adults categorized the tones based on the pitch information in the filtered stimuli. All mothers' tones were categorized with ceiling accuracy. Counter to the findings in most previous studies on children's tone acquisition and the prevailing assumption in models of speech development that children acquire suprasegmental features much earlier than segmental features, this study found that children as old as six years of age have not mastered the production of Mandarin tones. Children's tones were judged with significantly lower accuracy than mothers' productions. Tone accuracy improved, while cross subject variability in tone accuracy decreased, with age. Children's tone accuracy was affected by the articulatory complexity of phonetic contexts. Children made more errors in tone combinations with more complex fundamental frequency (F0) contours than tone sequences with simpler F0 changes. When producing disyllabic tone sequences with complex F0 contours, children tended to shift the F0 contour of the first tone to reduce the F0 change, resulting in more tone errors in the first syllable than in the second syllable and showing substantially more anticipatory coarticulation than adults. The results provide further evidence that acquisition of lexical tones is a protracted process in children. Tones produced accurately by children in one phonetic context may not be produced correctly in another phonetic context. Children demonstrate more anticipatory coarticulation in their disyllabic productions than adults, which may be attributed to children's immature speech motor control in tone production, and is presumably a by-product of their inability to accomplish complex F0 changes within the syllable time-frame.

Perceptual Improvement of Lexical Tones in Infants: Effects of Tone Language Experience

To learn words in a tonal language, tone-language learners should not only develop better abilities for perceiving consonants and vowels, but also for lexical tones. The divergent trend of enhancing sensitivity to native phonetic contrasts and reduced sensitivity to non-native phonetic contrast is theoretically essential to evaluate effects of listening to an ambient language on speech perception development. The loss of sensitivity in discriminating lexical tones among non-tonal language-learning infants was apparent between 6 and 12 months of age, but only few studies examined trends of differentiating native lexical tones in infancy. The sensitivity in discriminating lexical tones among 6-8 and 10-12 month-old Mandarin-learning infants (n = 120) was tested in Experiment 1 using three lexical tone contrasts of Mandarin. Facilitation of linguistic experience was shown in the tonal contrast (Tone 1 vs. 3), but both age groups performed similar in the other two tonal contrasts (Tone 2 vs. 4; Tone 2 vs. 3). In Experiment 2, 6-8 and 10-12 month-old Mandarin-learning infants (n = 90) were tested with tonal contrasts that have pitch contours either similar to or inverse from lexical tones in Mandarin, and perceptual improvement was shown only in a tonal contrast with familiar pitch contours (i.e., Tone 1 vs. 3). In Experiment 3, 6-8 and 10-12 month-old English-learning infants (n = 40) were tested with Tone 1 vs. 3 contrast of Mandarin and showed an improvement in the perception of non-native lexical tones. This study reveals that tone-language learning infants develop more accurate representations of lexical tones around their first birthday, and the results of both tone and non-tone language-learning infants imply that the rate of development depends on listening experience and the acoustical salience of specific tone contrasts.

Pitch Perception in the First Year of Life, a Comparison of Lexical Tones and Musical Pitch

Pitch variation is pervasive in speech, regardless of the language to which infants are exposed. Lexical tone is influenced by general sensitivity to pitch. We examined whether the development in lexical tone perception may develop in parallel with perception of pitch in other cognitive domains namely music. Using a visual fixation paradigm, 100 and one 4- and 12-month-old Dutch infants were tested on their discrimination of Chinese rising and dipping lexical tones as well as comparable three-note musical pitch contours. The 4-month-old infants failed to show a discrimination effect in either condition, whereas the 12-month-old infants succeeded in both conditions. These results suggest that lexical tone perception may reflect and relate to general pitch perception abilities, which may serve as a basis for developing more complex language and musical skills.

Limits on Monolingualism? A Comparison of Monolingual and Bilingual Infants' Abilities to Integrate Lexical Tone in Novel Word Learning

To construct their first lexicon, infants must determine the relationship between native phonological variation and the meanings of words. This process is arguably more complex for bilingual learners who are often confronted with phonological conflict: phonological variation that is lexically relevant in one language may be lexically irrelevant in the other. In a series of four experiments, the present study investigated English-Mandarin bilingual infants' abilities to negotiate phonological conflict introduced by learning both a tone and a non-tone language. In a novel word learning task, bilingual children were tested on their sensitivity to tone variation in English and Mandarin contexts. Their abilities to interpret tone variation in a language-dependent manner were compared to those of monolingual Mandarin learning infants. Results demonstrated that at 12-13 months, bilingual infants demonstrated the ability to bind tone to word meanings in Mandarin, but to disregard tone variation when learning new words in English. In contrast, monolingual learners of Mandarin did not show evidence of integrating tones into word meanings in Mandarin at the same age even though they were learning a tone language. However, a tone discrimination paradigm confirmed that monolingual Mandarin learning infants were able to tell these tones apart at 12-13 months under a different set of conditions. Later, at 17-18 months, monolingual Mandarin learners were able to bind tone variation to word meanings when learning new words. Our findings are discussed in terms of cognitive adaptations associated with bilingualism that may ease the negotiation of phonological conflict and facilitate precocious uptake of certain properties of each language.