Miwako Hisagi

Perception of Japanese Temporally-cued Contrasts by American English Listeners

American listeners’ perception of Japanese contrasts of vowel length (e.g., kiro vs. kiiro), consonant length (e.g., kite vs. kitte) and syllable number/length (e.g., kjoo vs. kijoo) was examined. Stimuli consisted of sentence-length utterances produced by a native Japanese talker; five minimal pairs of each contrast type were included. Questions were: a) can American listeners with no Japanese experience discriminate these contrasts, b) are there differences in relative difficulty of the three contrast types, and c) do instructions and other task variables affect performance accuracy? A categorial AXB discrimination task was used in two studies: Study 1 tested the three contrast types presented in separate blocks with detailed instructions about what to listen for; Study 2 tested the contrast types presented randomly intermixed with no specific instructions about the nature of the contrasts. Results indicated that naïve American listeners could discriminate all three contrast types well above chance, and that there were no significant overall differences in relative difficulty across contrast types. Performance was significantly poorer in Study 2 where listeners’ attention had not been directed to the nature of the contrasts. In both studies, there was significant and large variability in accuracy across different minimal pairs of each contrast type.

Cross-language perceptual similarity predicts categorial discrimination of American vowels by naïve Japanese listeners

Current speech perception models propose that relative perceptual difficulties with non-native segmental contrasts can be predicted from cross-language phonetic similarities. Japanese (J) listeners performed a categorical discrimination task in which nine contrasts (six adjacent height pairs, three front/back pairs) involving eight American (AE) vowels [iː, ɪ, ε, æː, ɑː, ʌ, ʊ, uː] in /hVbə/ disyllables were tested. The listeners also completed a perceptual assimilation task (categorization as J vowels with category goodness ratings). Perceptual assimilation patterns (quantified as categorization overlap scores) were highly predictive of discrimination accuracy (r(s)=0.93). Results suggested that J listeners used both spectral and temporal information in discriminating vowel contrasts.

ERP indices of vowel processing in Spanish–English bilinguals

This study examined behavioral and neurophysiological indices of discrimination of an English vowel contrast [[ɪ–ɛ] by early and late bilingual Spanish-English speakers, compared to monolingual English speakers. Electrophysiological measures (Mismatched Negativity - MMN) and behavioral measures (AX discrimination and forced-choice identification) were employed to examine perception of a nine-step vowel continuum, re-synthesized from natural tokens. Results revealed that (i) both monolingual and early bilinguals showed similar behavioral perception while late bilinguals performed more poorly on all behavioral tasks; and (ii) monolinguals showed robust evidence of discrimination (MMN) at a pre-attentive level that was significantly larger than found for either early or late bilinguals. These findings suggested that early input of English vowels to bilinguals did not necessarily lead to robust, automatic processing, as measured at a more attention-independent neural level; but earlier experience with a second language allowed for native-like speech perception measured with behavioral tasks.

Neural measures of a Japanese consonant length discrimination by Japanese and American English listeners: Effects of attention.

This study examined automaticity of discrimination of a Japanese length contrast for consonants (miʃi vs. miʃʃi) in native (Japanese) and non-native (American-English) listeners using behavioral measures and the event-related potential (ERP) mismatch negativity (MMN). Attention to the auditory input was manipulated either away from the auditory input via a visual oddball task (Visual Attend), or to the input by asking the listeners to count auditory deviants (Auditory Attend). Results showed a larger MMN when attention was focused on the consonant contrast than away from it for both groups. The MMN was larger for consonant duration increments than decrements. No difference in MMN between the language groups was observed, but the Japanese listeners did show better behavioral discrimination than the American English listeners. In addition, behavioral responses showed a weak, but significant correlation with MMN amplitude. These findings suggest that both acoustic-phonetic properties and phonological experience affects automaticity of speech processing. This article is part of a Special Issue entitled SI: Prediction and Attention.

Temporal and spectral variability of vowels within and across languages with small vowel inventories: Russian, Japanese, and Spanish

Variability of vowels in three languages with small vowel inventories (Russian, Japanese, and Spanish) was explored. Three male speakers of each language produced vowels in two‐syllable nonsense words (VCa) in isolation and three‐syllable nonsense words (gaC1VC2a) embedded within carrier sentences in three contexts: bilabial stops in normal rate sentences and alveolar stops in both normal and rapid rate sentences. Dependent variables were syllable duration and formant frequency at syllable midpoint. Results showed very little variation across consonant and rate conditions in formants for /i/ in Russian and Japanese. Japanese short /u, o, a/ showed fronting (F2 increases) in alveolar context, which was more pronounced in rapid sentences. Fronting of Japanese long vowels was less pronounced. Japanese long/short vowel ratios varied with speaking style (isolation versus sentences) and speaking rate. All Russian vowels except /i/ were fronted in alveolar context, but showed little change in either spectrum or ...

Neurophysiological basis of temporally cued phonetic contrasts in Japanese and American English listeners

The present study examined American English (AE) listeners’ perception of Japanese (JP) temporally cued contrasts of vowels and consonants. The mismatch negativity (MMN) component of event‐related potentials (ERPs) was used as a measure to compare passive (visual‐attention condition) and active (auditory‐attention condition) discrimination in an oddball paradigm. JP nonsense temporally cued vowel ([tado] vs [taado]) and consonant contrasts ([mi■i] vs [mi■■i]) were presented to JP listeners, for whom the temporal cues are contrastive, and to AE listeners who have no knowledge of JP. The following results were obtained. (1) With respect to the type of contrast, MMNs were larger for vowel contrasts than consonant contrasts. (2) In the auditory‐attention condition both groups showed a robust MMN to vowels. (3) In the visual‐attention condition JP also showed a robust MMN, while AE showed a smaller amplitude or absent MMN. This group difference was significant for the vowel contrast. (4) Interestingly, in the ...

Within‐ and across‐language spectral and temporal variability of vowels in different phonetic and prosodic contexts: Russian and Japanese

Contextual variability of vowels in three languages with large vowel inventories was examined previously. Here, variability of vowels in two languages with small inventories (Russian, Japanese) was explored. Vowels were produced by three female speakers of each language in four contexts: (Vba) disyllables and in 3‐syllable nonsense words (gaC1VC2a) embedded within carrier sentences; contexts included bilabial stops (bVp) in normal rate sentences and alveolar stops (dVt) in both normal and rapid rate sentences. Dependent variables were syllable durations and formant frequencies at syllable midpoint. Results showed very little variation across consonant and rate conditions in formants for /i/ in both languages. Japanese short /u, o, a/ showed fronting (F2 increases) in alveolar context relative to labial context (1.3‐2.0 Barks), which was more pronounced in rapid sentences. Fronting of Japanese long vowels was less pronounced (0.3 to 0.9 Barks). Japanese long/short vowel ratios varied with speaking style (syllables versus sentences) and speaking rate. All Russian vowels except /i/ were fronted in alveolar vs labial context (1.1‐3.1 Barks) but showed little change in either spectrum or duration with speaking rate. Comparisons of these patterns of variability with American English, French and German vowel results will be discussed.

Perceptual assimilation and categorial discrimination of American vowels by Japanese listeners

Best’s Perception Assimilation Model predicts that relative difficulty discriminating non‐native (L2) contrasts is predictable from perceived similarity of L2 segments and native (L1) segments. Japanese listeners performed a categorial discrimination task in which 9 vowel pairs (6 adjacent height pairs, 3 front‐back pairs) involving 6 tokens (2 speakers/3 repetitions) of each of 8 American vowels / i, I, e, ae, a, ■, U, u/ were tested in the context of hVba disyllables. In a second task, listeners were asked to categorize all stimuli with respect to which Japanese vowel they were most similar, and to rate their goodness on a 9‐point Likert scale. Overall error rates on height pairs ranged from 1 percent to 29 percent, and on front/back pairs, from 1 percent to 18 percent. The most difficult height contrasts were /U‐u/ and /a‐■/; perceptual assimilation patterns showed that these pairs were assimilated to the same Japanese vowels (Single Category or Category Goodness pattern) although /a‐■/ were assimilated...

ERP indices of speech processing in bilinguals

The specific aim of this project was to examine perceptual differentiation of the vowel contrast [I‐E] by early versus late bilingual Spanish–English speakers, compared to monolingual English speakers. Neither of these phonetic segments occur as phonemes in Spanish while they constitute phonemic contrast in English. For Spanish listeners, these vowels may be heard as variants of the Spanish phonemes [i] and [e], respectively. The formation of perceptual categories may be affected by exposure to two languages in which the phonemic status of phonetic segments differs. In the current study, electrophysiological measures (mismatched negativity—MMN) and behavioral measures (AX discrimination and identification) were employed to examine perception of a nine‐step continuum resynthesized from natural tokens. Preliminary results indicate that early bilinguals show somewhat more categorical perception than monolinguals (i.e., sharper identification boundaries) of the nine‐step continuum. MMN results, obtained durin...

Second-language learning effects on automaticity of speech processing of Japanese phonetic contrasts: An MEG study

We examined discrimination of a second-language (L2) vowel duration contrast in English learners of Japanese (JP) with different amounts of experience using the magnetoencephalography mismatch field (MMF) component. Twelve L2 learners were tested before and after a second semester of college-level JP; half attended a regular rate course and half an accelerated course with more hours per week. Results showed no significant change in MMF for either the regular or accelerated learning group from beginning to end of the course. We also compared these groups against nine L2 learners who had completed four semesters of college-level JP. These 4-semester learners did not significantly differ from 2-semester learners, in that only a difference in hemisphere activation (interacting with time) between the two groups approached significance. These findings suggest that targeted training of L2 phonology may be necessary to allow for changes in processing of L2 speech contrasts at an early, automatic level.