Training Japanese listeners to perceive American English vowels: influence of training sets

Memory-card vowel training for child and adult second-language learners: A first report

Japanese adults and Spanish-Catalan children received auditory phonetic training for English vowels using a novel paradigm, a version of the common children's card game Concentration. Individuals played a computer-based game in which they turned over pairs of cards to match spoken words, drawn from sets of vowel minimal pairs. The training was effective for adults, improving vowel recognition in a game that did not explicitly require identification. Children likewise improved over time on the memory card game, but not on the present generalisation task. This gamified training method can serve as a platform for examining development and perceptual learning.

Perceptual Learning of Altered Vowel Space Improves Identification of Vowels Produced by Individuals With Dysarthria Secondary to Amyotrophic Lateral Sclerosis

PURPOSE

This study examines the efficacy of perceptual training for improving typical listeners' identification of vowels produced by individuals with dysarthria. We examined whether training on a subset of vowels can generalize to (a) untrained vowels and (b) other speakers with similar overall intelligibility.

METHOD

Sixty naive listeners completed a pretest/posttest perceptual learning task. In the pretraining test and posttraining test, participants identified nine American English monophthongs produced by two speakers with dysarthria secondary to amyotrophic lateral sclerosis (ALS). In the 20-min training task, a two-alternative forced choice (2AFC) task with feedback trained listeners on a subset of the vowels and speakers presented in the pretraining test.

RESULTS

Vowel identification accuracy improved overall as a function of training. However, patterns of generalization between speakers and vowel types were not symmetric. Specifically, listeners generalized training from front vowels to back vowels but not vice versa. Likewise, listeners generalized from one speaker to another but not in the opposite direction. Examination of confusion matrices for the pretraining and posttraining revealed complex patterns of vowel-specific improvement.

CONCLUSIONS

This study demonstrates that listeners benefit from a very simple training paradigm targeting vowels. Additionally, error patterns revealed that vowels are both resistant to and responsive to perceptual learning. Implications for future research and clinical training paradigms are discussed.

Characteristics of Effective Auditory Training: Implications From Two Training Programs That Successfully Trained Nonnative Cantonese Tone Identification in Monolingual Mandarin and Bilingual Mandarin-Taiwanese Tone Speakers

Purpose Auditory training is important in pedagogical and clinical settings. In search of a more effective perceptual program for training new suprasegmental categories, this study examined the effect of two auditory programs that incorporated five elements that have previously been identified to be effective for training nonnative segmental and suprasegmental speech sounds on the identification of a complex foreign lexical tone system (Cantonese) that contrasts both pitch shapes and pitch heights. To investigate the training outcomes in learners with different tonal systems, monolingual Mandarin-speaking learners who have a smaller native tonal system that contrasts pitch shapes only and bilingual Mandarin-Taiwanese-speaking learners who have a larger native tonal system that contrasts both pitch shapes and pitch heights were recruited for training. Method Thirty Mandarin-speaking monolinguals and 33 Mandarin-Taiwanese-speaking bilinguals in Taiwan were randomly assigned to two training programs, one with different tones and the other with the same tone preceding the target words in the same training block, and received six 90-min training sessions within 2 weeks. They took a Cantonese Tone Identification Test before training and after each training session. Twenty Cantonese native speakers in Hong Kong served as the reference group and took the same Cantonese Tone Identification Test. Results The two training programs were equally effective. Before training, the monolinguals performed poorer than the bilinguals. After training, the monolinguals and bilinguals in both training programs identified the six Cantonese tones in new words, new utterances, and novel speakers with comparable results, and their overall accuracy did not differ from that of the Cantonese native speakers. Conclusions Though learners with a larger and more complex native tonal system have initial advantage in learning nonnative tones, the intensive high-variability full-set training programs that provide explicit phonetic instruction and contrastive feedback of nonnative tones effectively promote nonnative tone acquisition in learners of different tone languages. The findings revealed factors affecting nonnative tone acquisition in tone speakers. The design of the two programs can be adopted in future programs for effective auditory training of segmental and suprasegmental speech sounds.

Training non-native vowel perception: In quiet or noise

Noise makes speech perception much more challenging for non-native listeners than for native listeners. Training for non-native speech perception is usually implemented in quiet. It remains unclear if background noise may benefit or hamper non-native speech perception learning. In this study, 51 Chinese-native listeners were randomly assigned into three groups, including vowel training in quiet (TIQ), vowel training in noise (TIN), and watching videos in English as an active control. Vowel identification was assessed before (T1), right after (T2), and three months after training (T3) in quiet and various noise conditions. Results indicated that compared with the video watching group, the TIN group improved vowel identification in both quiet and noise significantly more at T2 and at T3. In contrast, the TIQ group improved significantly more in quiet and also in non-speech noise conditions at T2, but the improvement did not hold at T3. Moreover, compared to the TIQ group, the TIN group showed significantly less informational masking at both T2 and T3 and less energetic masking at T3. These results suggest that L2 speech training in background noise may improve non-native vowel perception more effectively than TIQ background only. The implications for non-native speech perception learning are discussed.

Effects of Phonetic Training on the Discrimination of Second Language Sounds by Learners with Naturalistic Access to the Second Language

The present study investigates the effect of high variability phonetic training (HVPT) on the discrimination of second language (L2) vowel contrasts by adult speakers who live in a country where the L2 is dominant. The same subjects who participated in a previous discrimination task were trained in the discrimination of four L2 vowel contrasts which were relatively difficult for this population of learners. Both the post-test and the generalization test showed significant improvement in the discrimination of most vowel contrasts (both stressed and unstressed). The findings suggest that HVPT may facilitate the formation of robust L2 phonological representations even for learners who live and are educated in an L2-dominant environment, dissolving in that way the perceptual confusions which emerge from first language interference. Finally, important implications are made for the implementation of HVPT in L2 classrooms.

Dissimilar Phonemes Create a Contextual Interference Effect During a Nonword Repetition Task

Purpose: The contextual interference effect is a motor learning phenomenon where conditions that decrease overall learning during practice enhance overall learning with new tasks. In the limb literature, this effect is observed when different practice conditions are used (e.g., blocked vs. random practice schedules). In speech motor learning, contextual interference effects are mixed. The differences observed during speech motor learning may be due to the stimuli used. We hypothesized that dissimilar phonemes might create interference during speech motor learning, such that training accuracy would decrease. However, generalization accuracy would increase compared to practice with nonwords containing similar phonemes.

Method: Thirty young adults with typical speech and hearing participated in a motor learning study using a cross-over design. Participants engaged in nonword repetition training followed by an immediate retention and transfer task with two sets of nonwords: nonwords with similar phonemes and nonwords with dissimilar phonemes. Percent consonants correct were calculated to examine the effects of the two different types of nonwords based on the stage of skill acquisition.

Results: A contextual interference effect was observed in this study using nonwords that varied in phonemic similarity. Nonwords with similar phonemes were produced with greater accuracy during the training stage of skill acquisition, and nonwords with dissimilar phonemes were produced with greater accuracy during the transfer stage.

Conclusion: The proposed hypothesis for this study was met – practicing nonwords with dissimilar phonemes resulted in greater accuracy in the transfer phase of this experiment. Results indicate that phonemic dissimilarity produced contextual interference and influenced speech motor learning. These results indicate that the linguistic properties of stimuli must be factored into speech motor learning. Future research should explore if other linguistic variables interact with variables of motor learning to enhance speech practice and generalization outcomes.

Mastery of Echoics in Chinese Establishes Bidirectional Naming in Chinese for Preschoolers with Naming in English

The onset of the verbal behavior developmental cusp of bidirectional naming (BiN) in a second language makes it possible for monolingual English-speaking children to learn names of things in a second language incidentally. We conducted 2 experiments to identify why monolingual English-speaking children cannot demonstrate BiN in another language when they demonstrated BiN in their native language. In Experiment I, using a group design (n = 32 preschoolers), we identified Chinese speech sounds that monolingual English-speaking children with BiN in English for familiar stimuli could not echo. In Experiment II, using a multiple-probe design, we investigated if mastery of echoics with the speech sounds identified in Experiment I would result in BiN in Chinese with 6 participants from Experiment I. The dependent variable was untaught responses to the probe stimuli presented following the naming experience based on the echoic stimuli from Experiment I. The results showed that echoic training was functionally related to the establishment of BiN in the second language. It appeared that the emission of accurate echoics might be the key to second-language BiN and that emergent correspondence between producing and hearing that occurs with the mastery of the echoic responding may be the source of reinforcement.

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.

Perceptual Training of Second-Language Vowels: Does Musical Ability Play a Role?

The present study attempts to extend the research on the effects of phonetic training on the production and perception of second-language (L2) vowels. We also examined whether success in learning L2 vowels through high-variability intensive phonetic training is related to the learners' general musical abilities. Forty Azerbaijani learners of Standard Southern British English participated in a pre-test/training/post-test setting. Discrimination and production tests were used in pre- and post-tests. The participants' musical ability was evaluated through three musical aptitude tests. Results revealed a significant improvement in the discrimination and production of L2 vowels after training. However, the lack of a one-to-one relationship between production and perception gains suggests distinct representations underlying L2 speech perception and production. There was no significant correlation between overall musical ability scores and L2 vowel learning, however, results revealed a correlation between discrimination improvements and tonal memory. This suggests tonal memory facilitates the perceptual learning of the novel phonological structure of L2.

Shifting Perceptual Weights in L2 Vowel Identification after Training

Difficulties with second-language vowel perception may be related to the significant challenges in using acoustic-phonetic cues. This study investigated the effects of perception training with duration-equalized vowels on native Chinese listeners' English vowel perception and their use of acoustic-phonetic cues. Seventeen native Chinese listeners were perceptually trained with duration-equalized English vowels, and another 17 native Chinese listeners watched English videos as a control group. Both groups were tested with English vowel identification and vowel formant discrimination before training, immediately after training, and three months later. The results showed that the training effect was greater for the vowel training group than for the control group, while both groups improved their English vowel identification and vowel formant discrimination after training. Moreover, duration-equalized vowel perception training significantly reduced listeners' reliance on duration cues and improved their use of spectral cues in identifying English vowels, but video-watching did not help. The results suggest that duration-equalized English vowel perception training may improve non-native listeners' English vowel perception by changing their perceptual weights of acoustic-phonetic cues.

Gradient of learnability in teaching English pronunciation to Korean learners

This paper aims to propose a gradient of learnability as a criterion for setting priorities in pronunciation teaching. A total of 40 Korean subjects (mostly aged 12 year) were tested on their discrimination ability of English sounds before and after participating in a high variability phonetic training (HVPT) program for 4 weeks. This study shows highly promising results for pronunciation teaching with the HVPT method. First, lower level learners show greater improvements in phoneme discrimination ability compared to upper level learners. Second, consonants are better discriminated than vowels and greater improvements are seen with consonant contrasts than with vowels that have a lower functional load. Third, many of the sounds with high functional load have a high learnability. Fourth, greater improvements are seen with sounds that are poorly identified before the training than sounds that are well-identified. Fifth, young learners also benefit from the HVPT, much like highly motivated adult learners. A learnability gradient was established on the basis of the phoneme learnability index and the pairwise learnability index. On the basis of the constructed gradient of learnability and the concept of functional load, a set of priorities was provided for teaching English pronunciation to young Korean learners.

Familiarization Effects on Consonant Intelligibility in Dysarthric Speech

BACKGROUND/AIMS

This study investigates the effects of familiarization on naïve listeners' ability to identify consonants in dysarthric speech.

METHODS

A total of 120 listeners (30 listeners/speaker) participated in experiments over a 6-week period. Listeners were randomly assigned to one of the three familiarization conditions: a passive condition in which listeners heard audio recordings of words, an active condition in which listeners heard audio recordings of words while viewing the written material of words, and a control condition in which listeners had no exposure to the audio signal prior to identification tasks.

RESULTS

Familiarization improved naïve listeners' ability to identify consonants produced by a speaker with dysarthria. The active familiarization method exhibited an advantage over the other conditions, in terms of the magnitude and rapidness of improvement. One-month delayed test scores were higher than pre-familiarization scores, but the advantage of active familiarization was not present for all speakers.

CONCLUSION

This study supports familiarization benefits in enhancing consonant intelligibility in dysarthria and suggests that perceptual learning mechanisms be harnessed for developing effective listener-oriented intervention techniques in the management of dysarthria. Current findings call for further research on a familiarization protocol that can subserve segmental learning with maximum efficacy.

Varying irrelevant phonetic features hinders learning of the feature being trained

Learning to distinguish nonnative words that differ in a critical phonetic feature can be difficult. Speech training studies typically employ methods that explicitly direct the learner's attention to the relevant nonnative feature to be learned. However, studies on vision have demonstrated that perceptual learning may occur implicitly, by exposing learners to stimulus features, even if they are irrelevant to the task, and it has recently been suggested that this task-irrelevant perceptual learning framework also applies to speech. In this study, subjects took part in a seven-day training regimen to learn to distinguish one of two nonnative features, namely, voice onset time or lexical tone, using explicit training methods consistent with most speech training studies. Critically, half of the subjects were exposed to stimuli that varied not only in the relevant feature, but in the irrelevant feature as well. The results showed that subjects who were trained with stimuli that varied in the relevant feature and held the irrelevant feature constant achieved the best learning outcomes. Varying both features hindered learning and generalization to new stimuli.

Familiarization effects on word intelligibility in dysarthric speech

BACKGROUND/AIMS

This study investigated the effects of familiarization on naïve listeners' ability to perceive dysarthric speech produced by speakers with cerebral palsy and evaluated the degree of intelligibility improvement, both in the short and long term, as a function of (1) familiarization paradigms and (2) the number of familiarization phases.

METHODS

A total of 120 listeners (30 listeners/speaker) were recruited to complete word transcription tasks over a 6-week period. The listeners were assigned to one of the following familiarization paradigms: passive familiarization with audio signal only, active familiarization with both audio and orthography, and no explicit familiarization. Intelligibility scores were measured as the percentage of words correctly transcribed.

RESULTS

The active familiarization paradigm that provided listeners with both audio and orthography resulted in higher intelligibility scores compared to the passive familiarization and no explicit familiarization conditions. The degree of intelligibility improvement as a function of passive familiarization varied depending on the speaker. Last, the advantage of active familiarization was also found as a long-term effect.

CONCLUSION

Our findings provide evidence for the benefits of familiarization in enhancing the intelligibility of dysarthric speech and support the efficacy of familiarization paradigms as an intervention technique in the management of dysarthria.

The early phase of /see symbol/ production development in adult Japanese learners of English

Although previous research indicates that Japanese speakers' second language (L2) perception and production of English /see symbol/ may improve with increased L2 experience, relatively little is known about the fine phonetic details of their /see symbol/ productions, especially during the early phase of L2 speech learning. This cross-sectional study examined acoustic properties of word-initial /see symbol/ from 60 Japanese learners with a length of residence of between one month and one year in Canada. Their performance was compared to that of 15 native speakers of English and 15 low-proficiency Japanese learners of English. Formant frequencies (F2 and F3) and F1 transition durations were evaluated under three task conditions--word reading, sentence reading, and timed picture description. Learners with as little as two to three months of residence demonstrated target-like F2 frequencies. In addition, increased LOR was predictive of more target-like transition durations. Although the learners showed some improvement in F3 as a function of LOR, they did so mainly at a controlled level of speech production. The findings suggest that during the early phase of L2 segmental development, production accuracy is task-dependent and is influenced by the availability of L1 phonetic cues for redeployment in L2.

Effects of speech practice on fast mapping in monolingual and bilingual speakers

PURPOSE

This study examines the effects of the levels of speech practice on fast mapping in monolingual and bilingual speakers.

METHOD

Participants were 30 English-speaking monolingual and 30 Spanish-English bilingual young adults. Each participant was randomly assigned to 1 of 3 practice conditions prior to the fast-mapping task: (a) intensive speech practice, (b) moderate speech practice, or (c) no practice. In a fast-mapping experiment, each participant was briefly exposed to novel objects and their corresponding novel words. Participants' knowledge of the target novel words was assessed immediately after the exposures.

RESULTS

There were significant effects of speech practice on fast mapping for both monolingual and bilingual adults. It is important to note that participants' language experience also played a role in their fast-mapping performance.

CONCLUSION

The findings suggest that speech practice, interacting with language experience, facilitates the processes for fast mapping.

A cross-language study of compensation in response to real-time formant perturbation

Past studies have shown that when formants are perturbed in real time, speakers spontaneously compensate for the perturbation by changing their formant frequencies in the opposite direction to the perturbation. Further, the pattern of these results suggests that the processing of auditory feedback error operates at a purely acoustic level. This hypothesis was tested by comparing the response of three language groups to real-time formant perturbations, (1) native English speakers producing an English vowel /ε/, (2) native Japanese speakers producing a Japanese vowel (/e([inverted perpendicular])/), and (3) native Japanese speakers learning English, producing /ε/. All three groups showed similar production patterns when F1 was decreased; however, when F1 was increased, the Japanese groups did not compensate as much as the native English speakers. Due to this asymmetry, the hypothesis that the compensatory production for formant perturbation operates at a purely acoustic level was rejected. Rather, some level of phonological processing influences the feedback processing behavior.

The effect of native vowel processing ability and frequency discrimination acuity on the phonetic training of English vowels for native speakers of Greek

The perception and production of nonnative phones in second language (L2) learners can be improved via auditory training, but L2 learning is often characterized by large differences in performance across individuals. This study examined whether success in learning L2 vowels, via five sessions of high-variability phonetic training, related to the learners' native (L1) vowel processing ability or their frequency discrimination acuity. A group of native speakers of Greek received training, while another completed the pre-/post-tests but without training. Pre-/post-tests assessed different aspects of their L2 and L1 vowel processing and frequency acuity. L2 and L1 vowel processing were assessed via: (a) Natural English (L2) vowel identification in quiet and in multi-talker babble, and natural Greek (L1) vowel identification in babble; (b) the categorization of synthetic English and Greek vowel continua; and (c) discrimination of the same continua. Frequency discrimination acuity was assessed for a nonspeech continuum. Frequency discrimination acuity was related to measures of both L1 and L2 vowel processing, a finding that favors an auditory processing over a speech-specific explanation for individual variability in L2 vowel learning. The most efficient frequency discriminators at pre-test were also the most accurate both in English vowel perception and production after training.

Learning English vowels with different first-language vowel systems II: Auditory training for native Spanish and German speakers

This study investigated whether individuals with small and large native-language (L1) vowel inventories learn second-language (L2) vowel systems differently, in order to better understand how L1 categories interfere with new vowel learning. Listener groups whose L1 was Spanish (5 vowels) or German (18 vowels) were given five sessions of high-variability auditory training for English vowels, after having been matched to assess their pre-test English vowel identification accuracy. Listeners were tested before and after training in terms of their identification accuracy for English vowels, the assimilation of these vowels into their L1 vowel categories, and their best exemplars for English (i.e., perceptual vowel space map). The results demonstrated that Germans improved more than Spanish speakers, despite the Germans' more crowded L1 vowel space. A subsequent experiment demonstrated that Spanish listeners were able to improve as much as the German group after an additional ten sessions of training, and that both groups were able to retain this learning. The findings suggest that a larger vowel category inventory may facilitate new learning, and support a hypothesis that auditory training improves identification by making the application of existing categories to L2 phonemes more automatic and efficient.

Reverse hierarchies and sensory learning

Revealing the relationships between perceptual representations in the brain and mechanisms of adult perceptual learning is of great importance, potentially leading to significantly improved training techniques both for improving skills in the general population and for ameliorating deficits in special populations. In this review, we summarize the essentials of reverse hierarchy theory for perceptual learning in the visual and auditory modalities and describe the theory's implications for designing improved training procedures, for a variety of goals and populations.

Nonnative speech perception training using vowel subsets: effects of vowels in sets and order of training

PURPOSE

K. Nishi and D. Kewley-Port (2007) trained Japanese listeners to perceive 9 American English monophthongs and showed that a protocol using all 9 vowels (fullset) produced better results than the one using only the 3 more difficult vowels (subset). The present study extended the target population to Koreans and examined whether protocols combining the 2 vowel sets would provide more effective training.

METHOD

Three groups of 5 Korean listeners were trained on American English vowels for 9 days using one of the 3 protocols: fullset only, first 3 days on subset then 6 days on fullset, or first 6 days on fullset then 3 days on subset. Participants' performance was assessed by pre- and posttraining tests, as well as by a midtraining test.

RESULTS

(a) Fullset training was effective for Koreans as well as Japanese, (b) no advantage was found for the 2 combined protocols over the fullset-only protocol, and (c) sustained "nonimprovement" was observed for training using one of the combined protocols.

CONCLUSIONS

In using subsets for training on American English vowels, care should be taken not only in the selection of subset vowels but also in the training orders of subsets.