Lexical Tone Research Articles

Lexical tone as a cue in statistical word learning from bilingual input

Abstract Learners can track word-referent co-occurrences across individually-ambiguous naming events to form correct word-referent mappings, termed statistical word learning (SWL). Prior research largely focuses on learning from a single language input, where a referent co-occurs with a single word (1:1 mapping). Here, we tested adults’ SWL from a simulated bilingual environment, where one referent co-occurred with two words (2:1 mapping) and the two words were either differentiated by a linguistic cue (Mandarin lexical tones, Cued condition) or not (Uncued condition). Results showed that in the Cued condition, Chinese–English bilinguals (N = 38) outperformed Spanish–English bilinguals (N = 56) and English monolinguals (N = 55), while Spanish–English bilinguals and English monolinguals performed similarly. The three groups did not differ in the Uncued condition. Self-reported learning confidence and strategies showed limited conscious awareness of learning. Results demonstrate that familiarity with a linguistic cue boosts overall statistical word learning from bilingual input.

Enhancing Pronunciation Learning through High Variability Phonetic Training: A Meta-analysis

High-Variability Phonetic Training (HVPT) has demonstrated effectiveness in second language (L2) acquisition. This study utilizes a meta-analysis to explore the influence of high variability on learning L2 pronunciation and identifies the factors that moderate this impact. The studies were collected using a keyword search in the SCOPUS database. In total, our meta-analysis incorporated 18 primary studies that presented results obtained from experimental and control group designs, encompassing a total of 22 effect sizes. The results of our meta-analysis revealed that the overall effect size of HVPT on L2 pronunciation was medium (g = 0.77). Specifically, the effect size was large for consonant sounds and lexical tones, particularly pronounced when utilized by advanced learners. For beginners, the effect size was medium. The context in which the training was conducted also played a role, with a medium effect size observed when sentences were used. Additionally, the number of talkers involved in the study influenced the effect size, with a medium effect size found when 5 to 8 talkers were included. In other cases, the reported effect sizes were either small or non-significant.

Primacy of mouth over eyes to perceive audiovisual Mandarin lexical tones.

The visual cues of lexical tones are more implicit and much less investigated than consonants and vowels, and it is still unclear what facial areas contribute to facial tones identification. This study investigated Chinese and English speakers' eye movements when they were asked to identify audiovisual Mandarin lexical tones. The Chinese and English speakers were presented with an audiovisual clip of Mandarin monosyllables (for instance, /ă/, /à/, /ĭ/, /ì/) and were asked to identify whether the syllables were a dipping tone (/ă/, / ĭ/) or a falling tone (/ à/, /ì/). These audiovisual syllables were presented in clear, noisy and silent (absence of audio signal) conditions. An eye-tracker recorded the participants' eye movements. Results showed that the participants gazed more at the mouth than the eyes. In addition, when acoustic conditions became adverse, both the Chinese and English speakers increased their gaze duration at the mouth rather than at the eyes. The findings suggested that the mouth is the primary area that listeners utilise in their perception of audiovisual lexical tones. The similar eye movements between the Chinese and English speakers imply that the mouth acts as a perceptual cue that provides articulatory information, as opposed to social and pragmatic information.

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.

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.

Cognate translation priming with Chinese-Japanese bilinguals: No effect of interlingual phonological similarity.

Previous masked translation priming studies, especially those with different-script bilinguals, have shown that cognates provide more priming than noncognates, a difference attributed to cognates' phonological similarity. In our experiments employing a word naming task, we examined this issue for Chinese-Japanese bilinguals in a slightly different way, using same-script cognates as primes and targets. In Experiment 1, significant cognate priming effects were observed. The sizes of the priming effects were, however, statistically not different for phonologically similar (e.g., /xin4lai4/-/shiNrai/) and dissimilar cognate pairs (e.g., /bao3zheng4/- /hoshoR/), suggesting no impact of phonological similarity. In Experiment 2, using exclusively Chinese stimuli, we demonstrated a significant homophone priming effect using two-character logographic primes and targets, indicating that phonological priming is possible for two-character Chinese targets. However, priming only emerged for pairs that had the same tone pattern (e.g., /shou3wei4/-/shou3wei4/), suggesting that a match in lexical tone is crucial for observing phonologically based priming in that situation. Therefore, Experiment 3 involved phonologically similar Chinese-Japanese cognate pairs in which the similarity of their suprasegmental phonological features (i.e., lexical tone and pitch-accent information) was varied. Priming effects were statistically not different for tone/accent similar pairs (e.g., /guan1xin1/-/kaNsiN/) and dissimilar pairs (e.g., /man3zu2/-/maNzoku/). Our results indicate that phonological facilitation is not involved in producing cognate priming effects for Chinese-Japanese bilinguals. Possible explanations, based on underlying representations of logographic cognates, are discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Neural control of lexical tone production in human laryngeal motor cortex

In tonal languages, which are spoken by nearly one-third of the world’s population, speakers precisely control the tension of vocal folds in the larynx to modulate pitch in order to distinguish words with completely different meanings. The specific pitch trajectories for a given tonal language are called lexical tones. Here, we used high-density direct cortical recordings to determine the neural basis of lexical tone production in native Mandarin-speaking participants. We found that instead of a tone category-selective coding, local populations in the bilateral laryngeal motor cortex (LMC) encode articulatory kinematic information to generate the pitch dynamics of lexical tones. Using a computational model of tone production, we discovered two distinct patterns of population activity in LMC commanding pitch rising and lowering. Finally, we showed that direct electrocortical stimulation of different local populations in LMC evoked pitch rising and lowering during tone production, respectively. Together, these results reveal the neural basis of vocal pitch control of lexical tones in tonal languages.

The advantage of the music-enabled brain in accommodating lexical tone variabilities

The perception of multiple-speaker speech is challenging. People with music training generally show more robust and faster tone perception. The present study investigated whether music training experience can facilitate tonal-language speakers to accommodate speech variability in lexical tones. Native Cantonese musicians and nonmusicians were asked to identify Cantonese level tones from multiple speakers. Two groups were equally well in using context cues to normalize lexical tone variability at behavioral level. However, the advantage of music training was observed at cortical level. The time-domain ERP analysis suggested that musicians normalized lexical tone variability much earlier than nonmusicians (N1: 70–175 ms vs. P2: 175–280 ms). An exploratory source analysis further revealed that two groups probably relied on different cortical regions to normalize lexical tones. Left BA41 showed stronger involvement in musicians in accommodating tone variability, but right auditory cortex (including BA 41, 42 and 22) activated to a greater extend in nonmusicians.

Representational level matters for tone-word recognition: Evidence from form priming.

In a form priming experiment with a lexical decision task, we investigated whether the representational structure of lexical tone in lexical memory impacts spoken-word recognition in Mandarin. Target monosyllabic words were preceded by five types of primes: (1) the same real words (/lun4/-/lun4/), (2) real words with only tone contrasts (/lun2/-/lun4/), (3) unrelated real words (/pie3/-/lun4/), (4) pseudowords with only tone contrasts (*/lun3/-/lun4/), and (5) unrelated pseudowords (*/tai3/-/lun4/). We found a facilitation effect in target words with pseudoword primes that share the segmental syllable but contrast in tones (*/lun3/-/lun4/). Moreover, no evident form priming effect was observed in target words primed by real words with only tone contrasts (/lun2/-/lun4/). These results suggest that the recognition of a tone word is influenced by the representational level of tone accessed by the prime word. The distinctive priming patterns between real-word and pseudoword primes are best explained by the connectionist models of tone-word recognition, which assume a hierarchical representation of lexical tone.

Tracking the time-course of spoken word recognition of Cantonese Chinese in sentence context: Evidence from eye movements.

In this study, we conducted an eye-tracking experiment to investigate the effects of sentence context and tonal information on spoken word recognition processes in Cantonese Chinese. We recruited 60 native Cantonese listeners to participate in the eye-tracking experiment. The target words (phonologically similar words) were manipulated to either (1) a congruent context or (2) an incongruent context in the experiment. The resulting eye-movement patterns in the incongruent context condition clearly revealed that (1) sentence context produced a garden-path effect in the initial stage of the spoken word recognition processes and then (2) the lexical tone of the word (bottom-up information) overrode the contextual effects to help listeners to discriminate between different similar-sounding words during lexical access. In conclusion, the patterns of eye-tracking data show the interactive processes between the lexical tone (an acoustic cue within a Cantonese word) and sentence context played in different phases to the spoken word recognition of Cantonese Chinese.

Observing gesture at learning enhances subsequent phonological and semantic processing of L2 words: An N400 study

This study employed the N400 event-related potential (ERP) to investigate how observing different types of gestures at learning affects the subsequent processing of L2 Mandarin words differing in lexical tone by L1 English speakers. The effects of pitch gestures conveying lexical tones (e.g., upwards diagonal movements for rising tone), semantic gestures conveying word meanings (e.g., waving goodbye for to wave), and no gesture were compared. In a lexical tone discrimination task, larger N400s for Mandarin target words mismatching vs. matching Mandarin prime words in lexical tone were observed for words learned with pitch gesture. In a meaning discrimination task, larger N400s for English target words mismatching vs. matching Mandarin prime words in meaning were observed for words learned with pitch and semantic gesture. These findings provide the first neural evidence that observing gestures during L2 word learning enhances subsequent phonological and semantic processing of learned L2 words.

The flexibility and representational nature of phonological prediction in listening comprehension: evidence from the visual world paradigm

AbstractUsing the visual world paradigm with printed words, this study investigated the flexibility and representational nature of phonological prediction in real-time speech processing. Native speakers of Mandarin Chinese listened to spoken sentences containing highly predictable target words and viewed a visual array with a critical word and a distractor word on the screen. The critical word was manipulated in four ways: a highly predictable target word, a homophone competitor, a tonal competitor, or an unrelated word. Participants showed a preference for fixating on the homophone competitors before hearing the highly predictable target word. The predicted phonological information waned shortly but was re-activated later around the acoustic onset of the target word. Importantly, this homophone bias was observed only when participants were completing a ‘pronunciation judgement’ task, but not when they were completing a ‘word judgement’ task. No effect was found for the tonal competitors. The task modulation effect, combined with the temporal pattern of phonological pre-activation, indicates that phonological prediction can be flexibly generated by top-down mechanisms. The lack of tonal competitor effect suggests that phonological features such as lexical tone are not independently predicted for anticipatory speech processing.

Cortical processing of Mandarin lexical tone in children with different language backgrounds

Bilingual experience modulates cognitive skills, particularly executive control. However, it is not clear if such modulation can be observed in automatic speech processing. Furthermore, it is unknown if bi-dialectal experience will enhance speech processing. This study aims to investigate whether and how early bilingual experience influences cortical sensitivity for automatic cortical processing of speech, specifically in the context of tonal and non-tonal languages. A passive listening oddball paradigm with two lexical tone contrasts were used and event-related potentials were recorded. An easy contrast (tone 1 versus tone 3) and a hard contrast (tone 2 versus tone 3) were used as the stimuli. Children between 5 and 10 years of age were tested. Preliminary results indicate that monolingual mainstream English, African-American English, and bilingual Mandarin-English learners all showed similar brain responses to the easy lexical tone contrast. However, there was an age effect across language groups. Such results suggest that biological factors such as age are stronger predictors of brain responses to lexical tone contrasts comparing to the factor of language background.

Categorization and discrimination of Mandarin lexical tones by naïve English listeners

Unlike tone languages such as Mandarin, English lacks tones at the sub-lexical level. Accordingly, English listeners have difficulty perceptually assimilating tones as categorized or uncategorized native segments (Perceptual Assimilation Model, PAM: Best, 1995). While English listeners can categorize the four lexical tones of Mandarin, i.e., level contour, rising, dipping, and falling, when given question, statement, exclamation, and uncertainty intonations as category choices (So & Best, 2011, 2014), this does not address tone assimilation at the segmental level. We reasoned that they might assimilate tones as non-assimilable nonspeech patterns if given visual icons as tone category choices (flat, rising, dipping, and falling lines, respectively), with no reference being made to English intonation categories. Accordingly, 76 monolingual English listeners (M age = 24.85 years, 50 females) were set two tasks: to use visual icons to categorize Mandarin tones in naturally produced tone-words (/ga, ti, tu, pu/ × 4 tones) and to discriminate all six pairwise tone contrasts. All tone pairs showed ceiling-level discrimination, and listeners split their categorizations of falling and level stimuli between the falling and flat icons, suggesting that when given visual icons, tone-naïve English listeners perceive Mandarin tones as nonspeech acoustic patterns, which is consistent with PAM’s non-assimilation predictions.

Neural encoding of Cantonese and Vietnamese tones

The present pilot study investigates the neural encoding of lexical tones in Cantonese and Vietnamese. Better encoding of tones was found in native than non-native tone language speakers in previous research, with fewer studies examining language-specific effects. An identical equipment setup was used to measure neural responses to three lexical tones in Hong Kong (HK) (by Cantonese speakers) and Ho Chi Minh City (by Vietnamese speakers). The three tones were the high rising (35), dipping (214), and low falling (21) tones, of which the 21 and 214 tones were unique to Cantonese and Vietnamese respectively. If better tone encoding is language-specific, Vietnamese and Cantonese adult speakers are expected to show enhanced encoding of these tones. Across the majority of temporal and spectral measures, we did not find significant group differences across tonal categories, suggesting that enhancement of neural encoding found in native speakers was likely to be language general. If confirmed with a larger sample size, these findings may suggest that clinical tools utilizing speech stimuli for the assessment of spoken language processing and its related functions may not necessarily require customization for a specific language. [Work supported by ITF in HK.]

Cochlear implant pitch and lexical tone perception in quiet and noise using F0-rate coding

Fundamental frequency (F0) cues to voice/musical pitch can be coded by pulse-rate or amplitude modulation (AM) rate of electrical pulse-trains in cochlear implant (CI) systems. However, for most clinical strategies (e.g., ACE), temporal cues to F0 are often poorly coded, particularly for female and children's voices and/or in background noise. Strategies such as Optimized Pitch And Language (OPAL) and Fundamental Asynchronous Stimulus Timing (FAST) enhance temporal F0 cues. For OPAL, F0 is estimated and used to control the AM rate coded by electrical pulse-trains in channel containing harmonics of F0. Significant benefits of OPAL to pitch ranking, speech intonation, and Mandarin lexical tone recognition have been observed compared to ACE. For FAST, peak-timing information in channel envelopes is used to derive pulse-timing in each channel and therefore much lower stimulation rates are provided resulting in longer battery life. In bilateral CI systems, it provides better ITD sensitivity, lateralization, and spatial release from masking compared to ACE. Presented here are the results of two studies, the first explored pitch perception of harmonic tones presented in quiet and noise using experimental OPAL and FAST strategies, and the second examined Mandarin lexical tone perception in quiet and noise using ACE and OPAL in a clinical processor.

Using L1 tone and intonation categories to investigate patterns in nonnative tone identification

Many languages utilise lexical tone, a feature which assigns meaning to words through variations in pitch contours. In some (but not all) cases, prior tone language experience can facilitate the learning of a nonnative tone language. Regardless, multiple sessions of tone training can improve nonnative tone perception for both tone and nontone L1 listeners. However, the influence of L1 tone and intonation categories on nonnative tone learning is underexplored. Across five sessions of tone training, listeners of nontonal English (n = 25), tonal Mandarin (n = 23), and tonal Vietnamese (n = 25) learned tones from an artificial language. While all groups improved in tone identification and tone word learning by session five (p < .001), Mandarin listeners outperformed the other groups overall (identification, p < .001; word learning, p < .05). Tone experience was a main effect only in word learning (p < .05). Tone- and language-specific identification patterns were also observed. The low level tone was easier for all listeners to perceive, while the tonal groups also showed greater accuracy for the mid level tone. Contrastingly, Mandarin listeners were hindered by their single L1 falling tone category when attempting to identify two distinct nonnative falling tones.

Multi-modal cross-linguistic perception of Mandarin tones in clear speech.

Clearly enunciated speech (relative to conversational, plain speech) involves articulatory and acoustic modifications that enhance auditory-visual (AV) segmental intelligibility. However, little research has explored clear-speech effects on the perception of suprasegmental properties such as lexical tone, particularly involving visual (facial) perception. Since tone production does not primarily rely on vocal tract configurations, tones may be less visually distinctive. Questions thus arise as to whether clear speech can enhance visual tone intelligibility, and if so, whether any intelligibility gain can be attributable to tone-specific category-enhancing (code-based) clear-speech cues or tone-general saliency-enhancing (signal-based) cues. The present study addresses these questions by examining the identification of clear and plain Mandarin tones with visual-only, auditory-only, and AV input modalities by native (Mandarin) and nonnative (English) perceivers. Results show that code-based visual and acoustic clear tone modifications, although limited, affect both native and nonnative intelligibility, with category-enhancing cues increasing intelligibility and category-blurring cues decreasing intelligibility. In contrast, signal-based cues, which are extensively available, do not benefit native intelligibility, although they contribute to nonnative intelligibility gain. These findings demonstrate that linguistically relevant visual tonal cues are existent. In clear speech, such tone category-enhancing cues are incorporated with saliency-enhancing cues across AV modalities for intelligibility improvements.

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.

Analysis of errors in Mandarin disyllabic tones produced by Vietnamese speakers

Abstract This study investigates the tone production of Mandarin disyllabic words by Vietnamese speakers. It aims to provide insights into the challenges Vietnamese speakers face when producing Mandarin tones in disyllabic words. In the study, there were 30 Vietnamese L2 learners of Mandarin, who were requested to produce 80 (4 tones × 4 tones × 5 words of each tonal combination) disyllabic words in Mandarin. The overall results showed that Tone 4 was the most difficult among the four lexical tones. In the first syllable, most errors were found for Tone 3 when followed by another Tone 3 (where the first Tone 3 should be pronounced as a rising tone, similar to Tone 2, but mispronounced as Tone 3), which indicated that Vietnamese speakers tend to underapply Mandarin third tone sandhi. In the second syllable, most errors were found for Tone 4 when preceded by Tone 4 (the second Tone 4 mispronounced as Tone 1). The findings can help explore how L2 production models can account for L2 production of Mandarin tones by considering effects of phonetic/phonological nature of Mandarin lexical tones as well as the interference arising from the L1 phonology of learners.