Speech sound learning depends on individuals' ability, not just experience

Distributional Learning and Overnight Consolidation of Nonnative Tonal Contrasts by Tonal Language Speakers

PURPOSE

Previous studies have reported the success of distributional learning for adult speakers across segmental and suprasegmental categories immediately after training. On the other hand, second language (L2) perception models posit that the ease with which learners perceive a nonnative speech contrast depends on the perceptual mapping between the contrast and learners' first language (L1) categories. This study examined whether a difference in perceptual mapping patterns for different L2-Mandarin tonal contrasts might result in a difference in distributional learning effectiveness for tonal speakers and whether an interval of sleep enhanced the knowledge through consolidation.

METHOD

Following a pretest-training-posttest design, 66 L1-Cantonese participants with fewer than 9 years of Mandarin training were assigned to either the bimodal or unimodal distribution conditions. The participants of each group were asked to discriminate Mandarin level-falling (T1-T4) and level-rising (T1-T2) tone pairs on novel syllables in a within-subject design. All participants were trained in the evening, tested after training, and returned after 12 hr for overnight consolidation assessment.

RESULTS

A significant distributional learning effect was observed for Mandarin T1-T4, but only after sleep. No significant distributional learning effect was observed for Mandarin T1-T2, either after training or after sleep.

CONCLUSIONS

The findings may imply that distributional learning is contingent on perceptual mapping patterns of the target contrasts and that sleep may play a role in the consolidation of knowledge in an implicit statistical learning paradigm.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25970008.

Native Language Perceptual Sensitivity Predicts Nonnative Speech Perception Differently in Younger and Older Singaporean Bilinguals

PURPOSE

We investigate in this study how individual variability in native language speech perception (termed Perceptual Sensitivity) influences nonnative speech perception in Singaporean Tamil-English bilinguals. Further, we assess if and how contextual and demographic factors influence Perceptual Sensitivity in the acquired languages and if the influence of Perceptual Sensitivity on nonnative speech perception is different across younger and older bilinguals.

METHOD

Perceptual Sensitivity in the native languages was examined by implementing Tamil and English gating tasks in 87 Singaporean Tamil-English bilinguals from two age groups (younger: 19-33 years; older: 55-70 years). Mandarin lexical tone discrimination was implemented as a measure of nonnative speech perception.

RESULTS

There was a wide range of variability in Perceptual Sensitivity scores in both languages across both age groups. Perceptual Sensitivity in the first native language (L1 Tamil) was a robust predictor of nonnative speech perception across both age groups, especially for the older bilinguals. However, general intelligence emerged as a stronger predictor than Tamil Perceptual Sensitivity in younger bilinguals. The influence of Tamil Perceptual Sensitivity on lexical tone perception was not tone-specific, supporting a general enhancement of lexical tone perception with better Tamil Perceptual Sensitivity. There was an influence of demographic factors on English Perceptual Sensitivity in older bilinguals, but not for Tamil and not in younger bilinguals.

CONCLUSIONS

Our findings corroborate with previous studies in showing that native language Perceptual Sensitivity is positively associated with and predicts nonnative speech perception in younger and older adulthood regardless of language similarity but to varying degrees. Specifically, the influence of Perceptual Sensitivity on nonnative speech perception is stronger in older adulthood, suggesting a possible shift in reliance on crystallized language knowledge with age. Proficiency and use, among other demographic and language variables, do not appear to influence L1 Perceptual Sensitivity in a lesser used language (Tamil) as significantly as previously assumed.

The Role of Talker Variability in Nonnative Phonetic Learning: A Systematic Review and Meta-Analysis

PURPOSE

High-variability phonetic training (HVPT) has been found to be effective on adult second language (L2) learning, but results are mixed in regards to the benefit of multiple talkers over single talker. This study provides a systematic review with meta-analysis to investigate the talker variability effect in nonnative phonetic learning and the factors moderating the effect.

METHOD

We collected studies with keyword search in major academic databases including EBSCO, ERIC, MEDLINE, ProQuest Dissertations & Theses, Elsevier, Scopus, Wiley Online Library, and Web of Science. We identified potential participant-, training-, and study-related moderators and conducted a random-effects model meta-analysis for each individual variable.

RESULTS

On the basis of 18 studies with a total of 549 participants, we obtained a small-level summary effect size (Hedges' g = 0.46, 95% confidence interval [CI; 0.08, 0.84]) for the immediate training outcomes, which was greatly reduced (g = -0.04, 95% CI [-0.46, 0.37]) after removal of outliers and correction for publication bias, whereas the effect size for immediate perceptual gains was nearly medium (g = 0.56, 95% CI [0.13, 1.00]) compared with the nonsignificant production gains. Critically, the summary effect sizes for generalizations to new talkers (g = 0.72, 95% CI [0.15, 1.29]) and for long-term retention (g = 1.09, 95% CI [0.39, 1.78]) were large. Moreover, the training program length and the talker presentation format were found to potentially moderate the immediate perceptual gains and generalization outcomes.

CONCLUSIONS

Our study presents the first meta-analysis on the role of talker variability in nonnative phonetic training, which demonstrates the heterogeneity and limitations of research on this topic. The results highlight the need for further investigation of the influential factors and underlying mechanisms for the presence or absence of talker variability effects. Supplemental Material https://doi.org/10.23641/asha.16959388.

Anterior insular thickness predicts speech sound learning ability in bilinguals

A previous fMRI study of novel speech sound learning, tied to the methods and results presented here, identified groups of advanced and novice learners and related their classification to neural activity. To complement those results and better elucidate the role of the entire neural system in speech learning, the current study analyzed the neuroanatomical data with the goals of 1) uncovering the regions of interest (ROIs) that predicted speech learning performance in a sample of monolingual and bilingual adults, and 2) examining if the relationship between cortical thickness from selected ROIs and individual learning ability depends on language group. The ROIs selected were brain regions well-established in the literature as areas associated with language and speech processing (i.e., Transverse Superior Temporal Gyrus, anterior insula and posterior insula, all bilaterally). High-resolution brain scans (T1-weighted) were acquired from 23 Spanish-English bilinguals and 20 English monolingual adults. The thickness of the left anterior insula significantly predicted speech sound learning ability in bilinguals but not monolinguals. These results suggest that aptitude for learning a new language is associated with variations in the cortical thickness of the left anterior insula in bilinguals. These findings may provide insight into the higher order mechanisms involved in speech perception and advance our understanding of the unique strategies employed by the bilingual brain during language learning.

Successful non-native speech perception is linked to frequency following response phase consistency

Some people who attempt to learn a second language in adulthood meet with greater success than others. The causes driving these individual differences in second language learning skill continue to be debated. In particular, it remains controversial whether robust auditory perception can provide an advantage for non-native speech perception. Here, we tested English speech perception in native Japanese speakers through the use of frequency following responses, the evoked gamma band response, and behavioral measurements. Participants whose neural responses featured less timing jitter from trial to trial performed better on perception of English consonants than participants with more variable neural timing. Moreover, this neural metric predicted consonant perception to a greater extent than did age of arrival and length of residence in the UK, and neural jitter predicted independent variance in consonant perception after these demographic variables were accounted for. Thus, difficulties with auditory perception may be one source of problems learning second languages in adulthood.