High or low? Comparing high and low-variability phonetic training in adult and child second language learners

Sustainable Benefits of High Variability Phonetic Training in Mandarin-speaking Kindergarteners With Cochlear Implants: Evidence From Categorical Perception of Lexical Tones

OBJECTIVES

Although pitch reception poses a great challenge for individuals with cochlear implants (CIs), formal auditory training (e.g., high variability phonetic training [HVPT]) has been shown to provide direct benefits in pitch-related perceptual performances such as lexical tone recognition for CI users. As lexical tones in spoken language are expressed with a multitude of distinct spectral, temporal, and intensity cues, it is important to determine the sources of training benefits for CI users. The purpose of the present study was to conduct a rigorous fine-scale evaluation with the categorical perception (CP) paradigm to control the acoustic parameters and test the efficacy and sustainability of HVPT for Mandarin-speaking pediatric CI recipients. The main hypothesis was that HVPT-induced perceptual learning would greatly enhance CI users' ability to extract the primary pitch contours from spoken words for lexical tone identification and discrimination. Furthermore, individual differences in immediate and long-term gains from training would likely be attributable to baseline performance and duration of CI use.

DESIGN

Twenty-eight prelingually deaf Mandarin-speaking kindergarteners with CIs were tested. Half of them received five sessions of HVPT within a period of 3 weeks. The other half served as control who did not receive the formal training. Two classical CP tasks on a tonal continuum from Mandarin tone 1 (high-flat in pitch) to tone 2 (mid-rising in pitch) with fixed acoustic features of duration and intensity were administered before (pretest), immediately after (posttest), and 10 weeks posttraining termination (follow-up test). Participants were instructed to either label a speech stimulus along the continuum (i.e., identification task) or determine whether a pair of stimuli separated by zero or two steps from the continuum was the same or different (i.e., discrimination task). Identification function measures (i.e., boundary position and boundary width) and discrimination function scores (i.e., between-category score, within-category score, and peakedness score) were assessed for each child participant across the three test sessions.

RESULTS

Linear mixed-effects (LME) models showed significant training-induced enhancement in lexical tone categorization with significantly narrower boundary width and better between-category discrimination in the immediate posttest over pretest for the trainees. Furthermore, training-induced gains were reliably retained in the follow-up test 10 weeks after training. By contrast, no significant changes were found in the control group across sessions. Regression analysis confirmed that baseline performance (i.e., boundary width in the pretest session) and duration of CI use were significant predictors for the magnitude of training-induced benefits.

CONCLUSIONS

The stringent CP tests with synthesized stimuli that excluded acoustic cues other than the pitch contour and were never used in training showed strong evidence for the efficacy of HVPT in yielding immediate and sustained improvement in lexical tone categorization for Mandarin-speaking children with CIs. The training results and individual differences have remarkable implications for developing personalized computer-based short-term HVPT protocols that may have sustainable long-term benefits for aural rehabilitation in this clinical population.

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.

Desirable Difficulties in Language Learning? How Talker Variability Impacts Artificial Grammar Learning

Contending with talker variability has been found to lead to processing costs but also benefits by focusing learners on invariant properties of the signal, indicating that talker variability acts as a desirable difficulty. That is, talker variability may lead to initial costs followed by long-term benefits for retention and generalization. Adult participants learned an artificial grammar affording learning of multiple components in two experiments varying in difficulty. They learned from one, two, or eight talkers and were tested at three time points. The eight-talker condition did not impact learning. The two-talker condition negatively impacted some aspects of learning, but only under more difficult conditions. Generalization of the grammatical dependency was difficult. Thus, we discovered that high and limited talker variability can differentially impact artificial grammar learning. However, talker variability did not act as a desirable difficulty in the current paradigm as the few evidenced costs were not related to long-term benefits.

Cross-talker generalization in the perception of nonnative speech: A large-scale replication

Speech perception depends on the ability to generalize previously experienced input effectively across talkers. How such cross-talker generalization is achieved has remained an open question. In a seminal study, Bradlow & Bent (2008, henceforth BB08) found that exposure to just 5 min of accented speech can elicit improved recognition that generalizes to an unfamiliar talker of the same accent (N = 70 participants). Cross-talker generalization was, however, only observed after exposure to multiple talkers of the accent, not after exposure to a single accented talker. This contrast between single- and multitalker exposure has been highly influential beyond research on speech perception, suggesting a critical role of exposure variability in learning and generalization. We assess the replicability of BB08's findings in two large-scale perception experiments (total N = 640) including 20 unique combinations of exposure and test talkers. Like BB08, we find robust evidence for cross-talker generalization after multitalker exposure. Unlike BB08, we also find evidence for generalization after single-talker exposure. The degree of cross-talker generalization depends on the specific combination of exposure and test talker. This and other recent findings suggest that exposure to cross-talker variability is not necessary for cross-talker generalization. Variability during exposure might affect generalization only indirectly, mediated through the informativeness of exposure about subsequent speech during test: Similarity-based inferences can explain both the original BB08 and the present findings. We present Bayesian data analysis, including Bayesian meta-analyses and replication tests for generalized linear mixed models. All data, stimuli, and reproducible literate (R markdown) code are shared via OSF. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Toddlers raised in multi-dialectal families learn words better in accented speech than those raised in monodialectal families

Multi-accent environments offer rich but inconsistent language input, as words are produced differently across accents. The current study examined, in two experiments, whether multi-accent variability affects infants' ability to learn words and whether toddlers' prior experience with accents modulates learning. In Experiment 1, two-and-a-half-year-old Norwegian toddlers were exposed, in their kindergarten, twice per day for one week, to a child-friendly audiovisual tablet-based e-book containing four novel pseudowords. Half of the toddlers heard the story in three Norwegian accents, whereas the other half heard it in one Norwegian accent. The results revealed no differences between conditions, suggesting that multi-accent variability did not hinder toddlers' word learning. In experiment 2, two-and-a-half-year-old Norwegian toddlers were exposed, in their homes, for one week, to the e-book featuring three Norwegian accents. The results revealed overall better learning in toddlers raised in bi-dialectal households, as compared to mono-dialectal peers - suggesting that accent exposure benefits learning in multi-accent environments.

Research on construction and innovation new foreign language classroom teaching mode based on the “Internet Plus”

Twenty-first Century is a global information age with rapid development of science and technology, and the information technology represented by multimedia and computer network changes our life and learning mode at extraordinary speed. Nowadays, the quality education is paid attention to by everyone. To further comply with the requirements of the new era curriculum teaching and personnel training, one of the general goals of the “English curriculum standards for senior high schools” promulgated by China in 2003 is to cultivate the “students’ comprehensive use of language skills” and to advocate the basic idea of “concern for students’ emotion”. Relying on the “Internet plus” background, this paper realizes the maintenance of basic data (thesaurus, question bank, article Library) through developing computer assisted foreign language teaching system, and teaching system is mainly to complete the overall design of the teaching system, which not only provides the basic data for the learning and testing of the foreign language assisted teaching system, but also lays a good foundation for the design and realization of the teaching system, and develops the game teaching interface. It has important research value to construct and innovate the new foreign language classroom teaching mode.

High-Variability Phonetic Training Benefits Lexical Tone Perception: An Investigation on Mandarin-Speaking Pediatric Cochlear Implant Users

Purpose Lexical tone perception is known to be persistently difficult for individuals with cochlear implants (CIs). The purpose of this study was to evaluate the efficacy of high-variability phonetic training (HVPT) in improving Mandarin tone perception for native-speaking children with CIs. Method A total of 28 Mandarin-speaking pediatric CI recipients participated in the study. Half of the children with CIs received a five-session HVPT within a period of 3 weeks. Identification and discrimination of lexical tones produced by familiar talkers (used during training) and novel talkers (not used during training) were measured before, immediately after, and 10 weeks after training termination. The other half untrained children served as control for the identical pre- and posttests. Results Lexical tone perception significantly improved in both trained identification task and untrained discrimination task for the trainees. There was also a significant effect in transfer of learning to perceiving tones produced by novel talkers. Moreover, training-induced gains were retained for up to 10 weeks after training. By comparison, no significant pre-post changes were observed in the control group. Conclusion The results provide the first systematical assessment for the efficacy of the HVPT protocol for Mandarin-speaking pediatric CI users with congenital hearing loss, which supports the clinical utility of intensive short-term HVPT in these children's rehabilitative regimens.

The effects of high versus low talker variability and individual aptitude on phonetic training of Mandarin lexical tones

High variability (HV) training has been found to be more effective than low variability (LV) training when learning various non-native phonetic contrasts. However, little research has considered whether this applies to the learning of tone contrasts. The only two relevant studies suggested that the effect of HV training depends on the perceptual aptitude of participants (Perrachione et al., 2011; Sadakata & McQueen, 2014). The present study extends these findings by examining the interaction between individual aptitude and input variability using natural, meaningful second language input (both previous studies used pseudowords). A total of 60 English speakers took part in an eight session phonetic training paradigm. They were assigned to high/low/high-blocked variability training groups and learned real Mandarin tones and words. Individual aptitude was measured following previous work. Learning was measured using one discrimination task, one identification task and two production tasks. All tasks assessed generalization. All groups improved in both the production and perception of tones which transferred to untrained voices and items, demonstrating the effectiveness of training despite the increased complexity compared with previous research. Although the LV group exhibited an advantage with the training stimuli, there was no evidence for a benefit of high-variability in any of the tests of generalisation. Moreover, although aptitude significantly predicted performance in discrimination, identification and training tasks, no interaction between individual aptitude and variability was revealed. Additional Bayes Factor analyses indicated substantial evidence for the null for the hypotheses of a benefit of high-variability in generalisation, however the evidence regarding the interaction was ambiguous. We discuss these results in light of previous findings.

The Role of Temporal Acoustic Exaggeration in High Variability Phonetic Training: A Behavioral and ERP Study

High variability phonetic training (HVPT) has been found to be effective in helping adult learners acquire non-native phonetic contrasts. The present study investigated the role of temporal acoustic exaggeration by comparing the canonical HVPT paradigm without involving acoustic exaggeration with a modified adaptive HVPT paradigm that integrated key temporal exaggerations in infant-directed speech (IDS). Sixty native Chinese adults participated in the training of the English /i/ and /i/ vowel contrast and were randomly assigned to three subject groups. Twenty were trained with the typical HVPT paradigm (the HVPT group), twenty were trained under the modified adaptive approach with acoustic exaggeration (the HVPT-E group), and twenty were in the control group. Behavioral tasks for the pre- and post- tests used natural word identification, synthetic stimuli identification, and synthetic stimuli discrimination. Mismatch negativity (MMN) responses from the HVPT-E group were also obtained to assess the training effects in within- and across- category discrimination without requiring focused attention. Like previous studies, significant generalization effects to new talkers were found in both the HVPT group and the HVPT-E group. The HVPT-E group, by contrast, showed greater improvement as reflected in larger progress in natural word identification performance. Furthermore, the HVPT-E group exhibited more native-like categorical perception based on spectral cues after training, together with corresponding training-induced changes in the MMN responses to within- and across- category differences. These data provide the initial evidence supporting the important role of temporal acoustic exaggeration with adaptive training in facilitating phonetic learning and promoting brain plasticity at the perceptual and pre-attentive neural levels.

High variability phonetic training in adaptive adverse conditions is rapid, effective, and sustained

This paper evaluates a novel high variability phonetic training paradigm that involves presenting spoken words in adverse conditions. The effectiveness, generalizability, and longevity of this high variability phonetic training in adverse conditions was evaluated using English phoneme contrasts in three experiments with Malaysian multilinguals. Adverse conditions were created by presenting spoken words against background multi-talker babble. In Experiment 1, the adverse condition level was set at a fixed level throughout the training and in Experiment 2 the adverse condition level was determined for each participant before training using an adaptive staircase procedure. To explore the effectiveness and sustainability of the training, phonemic discrimination ability was assessed before and immediately after training (Experiments 1 and 2) and 6 months after training (Experiment 3). Generalization of training was evaluated within and across phonemic contrasts using trained and untrained stimuli. Results revealed significant perceptual improvements after just three 20-minute training sessions and these improvements were maintained after 6 months. The training benefits also generalized from trained to untrained stimuli. Crucially, perceptual improvements were significantly larger when the adverse conditions were adapted before each training session than when it was set at a fixed level. As the training improvements observed here are markedly larger than those reported in the literature, this indicates that the individualized phonetic training regime in adaptive adverse conditions (HVPT-AAC) is highly effective at improving speech perception.