Japanese Vowel Length Research Articles

Vpliv besednega naglasa na zaznavo dolžine japonskega samoglasnika: Dokazi iz hrvaščine

The present paper examines the effect of Japanese lexical accent on the perception of Japanese vowel length in Croatian listeners. Lexical accent patterns of the two languages, both having phonologically distinctive length and pitch, are contrasted. A three-alternative choice identification test was conducted involving all combinations of three pitch patterns and two positions of a long vowel in bisyllabic words. Two groups of participants were Croatian students of Japanese and those without any prior knowledge. The results showed not only the effects of pitch pattern but also of the position of the long vowel (initial or final) and group. Participants had the highest error rates for pitch pattern LHL, followed by HLL, regardless of the group and position of the long vowel.

Australian English listeners' perception of Japanese vowel length reveals underlying phonological knowledge.

Speech perception patterns are strongly influenced by one's native phonology. It is generally accepted that native English listeners rely primarily on spectral cues when perceiving vowels, making limited use of duration cues because English lacks phonemic vowel length. However, the literature on vowel perception by English listeners shows a marked bias toward American English, with the phonological diversity among different varieties of English largely overlooked. The current study investigates the perception of Japanese vowel length contrasts by native listeners of Australian English, which is reported to use length to distinguish vowels unlike most other varieties of English. Twenty monolingual Australian English listeners participated in a forced-choice experiment, where they categorized Japanese long and short vowels as most similar to their native vowel categories. The results showed a general tendency for Japanese long and short vowels (e.g., /ii, i/) to be categorized as Australian English long and short vowels (e.g., /i:, ɪ/ as in "heed," "hid"), respectively, which contrasts with American English listeners' categorization of all Japanese vowels as tense regardless of length (e.g., /ii, i/ as both "heed") as reported previously. Moreover, this duration-based categorization was found not only for Australian English categories that contrast in duration alone (e.g., /ɐ:, ɐ/ as in "hard," "hud") but also for those that contrast in both duration and spectra (e.g., /o:, ɔ/ as in "hoard," "hod"), despite their spectral mismatch from the corresponding Japanese vowels (e.g., /aa, a/ and /oo, o/). The results, therefore, suggest that duration cues play a prominent role across all vowel categories-even nonnative-for Australian English listeners. The finding supports a feature-based framework of speech perception, where phonological features like length are shared across multiple categories, rather than the segment-based framework that is currently dominant, which regards acoustic cues like duration as being tied to a specific native segmental category. Implications for second and foreign language learning are discussed.

Effect of prior exposure on the perception of Japanese vowel length contrast in reverberation for nonnative listeners

While reverberation often degrades speech intelligibility, previous studies have shown that prior exposure to reverberation can reduce its adverse effects on speech perception. The current study investigated the effect of prior exposure to reverberation on the perception of nonnative speech sounds. We compared the results from two experiments, one in “blocked presentation” where the target words with the same amount of reverberation were presented to participants consistently, and another in “random presentation” where the amount of reverberation added to the target words changed between each trial. A Japanese minimal pair,/ie/ ‘house’ -/iie/ ‘no’, where vowel length creates a phonemic difference, was used as the target. The results for native listeners showed that their responses did not differ significantly between the blocked and random presentations. On the other hand, the effect of presentation type was significant in terms of the responses from the nonnative listeners. The results showed that nonnative listeners did not respond differently between the anechoic and reverberant conditions in the blocked presentation. However, there was a significant difference between the anechoic and reverberant conditions in the random presentation. The results from the nonnative listeners suggest that they try to obtain information of reverberation from the exposure since they could not use top-down processing effectively as much as native listeners.

インドネシア語話者による日本語の長短母音の習得に関する調査 : 聞き取り・読み上げ発話・自然発話のデータから

インドネシア語話者による日本語の長短母音の習得に関する調査 : 聞き取り・読み上げ発話・自然発話のデータから

Automatic recognition of Japanese vowel length accounting for speaking rate and motivated by perception analysis

Automatic recognition of vowel length in Japanese has several applications in speech processing such as for computer assisted language learning (CALL) systems. Standard automatic speech recognition (ASR) systems make use of hidden Markov models (HMMs) to carry out the recognition. However, HMMs are not particularly well-suited for this problem since classification of vowel length is dependent on prosodic information, and since it is a relative feature affected by changes in the durations of surrounding sounds which vary in part due to changes in speaking rates. That being said, it is not obvious how to design an algorithm to account for these contextual dependencies, since there is still not enough known about how humans perceive the contrast. Therefore, in this paper, we conduct perceptual experiments to further understand the mechanism of human vowel length recognition. In our research, we found that the perceptual boundary is largely affected by the vowels two prior, one prior, and following the vowel for which the length is being recognized. Based on these results and the works of others, we propose an algorithm which does post-processing on alignments output by HMMs to automatically recognize vowel length. The method is primarily composed of two levels of processing dealing first with local dependencies and then long-term dependencies. We test several variations of this algorithm. The method we develop is shown to have superior recognition capabilities and be robust against speaking rate differences producing significant improvements. We test this method on three different databases: a speaking rate database, a native database, and a non-native database.

Cross-Language Perception of Japanese Vowel Length Contrasts: Comparison of Listeners From Different First Language Backgrounds

The purpose of this research was to compare the perception of Japanese vowel length contrasts by 4 groups of listeners who differed in their familiarity with length contrasts in their first language (L1; i.e., American English, Italian, Japanese, and Thai). Of the 3 nonnative groups, native Thai listeners were expected to outperform American English and Italian listeners, because vowel length is contrastive in their L1. Native Italian listeners were expected to demonstrate a higher level of accuracy for length contrasts than American English listeners, because the former are familiar with consonant (but not vowel) length contrasts (i.e., singleton vs. geminate) in their L1. A 2-alternative forced-choice AXB discrimination test that included 125 trials was administered to all the participants, and the listeners' discrimination accuracy (d') was reported. As expected, Japanese listeners were more accurate than all 3 nonnative groups in their discrimination of Japanese vowel length contrasts. The 3 nonnative groups did not differ from one another in their discrimination accuracy despite varying experience with length contrasts in their L1. Only Thai listeners were more accurate in their length discrimination when the target vowel was long than when it was short. Being familiar with vowel length contrasts in L1 may affect the listeners' cross-language perception, but it does not guarantee that their L1 experience automatically results in efficient processing of length contrasts in unfamiliar languages. The extent of success may be related to how length contrasts are phonetically implemented in listeners' L1.

Non-native Japanese listeners’ perception of vowel length contrasts in Japanese and Modern Standard Arabic (MSA)

This study aimed to compare the perception of short vs. long vowel contrasts in Japanese and Modern Standard Arabic (MSA) by four groups of listeners differing in their linguistic backgrounds: native Arabic (NA), native Japanese (NJ), non-native Japanese (NNJ) and Australian English (OZ) speakers. The NNJ and OZ groups shared the first language (L1), but differed in their familiarity with Japanese. In both Japanese and MSA, vowel length is phonemic. In contrast, vowel duration plays a more limited (although not insignificant) role in English. Of interest was the discrimination accuracy of NNJ listeners who learned Japanese as a second (L2) or foreign language in adulthood. As expected, the NA and NJ groups discriminated their L1 contrasts more accurately than all the other groups, but the NNJ listeners showed a significant shift in their perceptual behaviour and outperformed the OZ listeners who have no knowledge of Japanese in discriminating the Japanese vowel length contrasts. Furthermore, NNJ was the only group who did not differ in their discrimination accuracy for the Arabic and Japanese stimuli. Taken together, the results obtained in this study suggest that NNJ learned to discriminate Japanese vowel length contrasts to some extent, but the learning did not carry over cross-linguistically to the processing of vowel length contrasts in an unknown language.

Non-native Japanese learners' perception of vowel length contrasts in Arabic and Japanese

This study examined the perception of short vs. long vowel contrasts in Arabic and Japanese by four groups of listeners differing in their linguistic backgrounds: native Arabic (NA), native Japanese (NJ), non-native Japanese (NNJ), and Australian English (OZ) speakers. Listeners' first languages differed in the extent to which vowel duration is used contrastively. In both Arabic and Japanese, vowel length is phonemic. English, on the other hand, utilizes vowel duration in a more limited way. Of interest was the discrimination accuracy of NNJ listeners who learned Japanese as a second language beyond childhood. As expected, the NA and NJ groups discriminated their native contrasts more accurately than all the other groups while the NNJ listeners showed a significant shift in their perceptual behavior and outperformed the OZ listeners who had no knowledge of Japanese in discriminating the Japanese vowel length contrasts. Furthermore, NNJ was the only group who showed a balanced pattern of discrimination acc...

Perception of a Japanese vowel length contrast by Japanese and American English listeners: Behavioral and electrophysiological measures

This study examined the role of automatic selective perceptual processes in native and non-native listeners' perception of a Japanese vowel length contrast (t ado vs. t aado), using multiple, natural-speech tokens of each category as stimuli in a “categorial oddball” design. Mismatch negativity (MMN) was used to index discrimination of the temporally-cued vowel contrast by naïve adult American listeners and by a native Japanese-speaking control group in two experiments in which attention to the auditory input was manipulated: in Exp 1 (Visual-Attend), listeners silently counted deviants in a simultaneously-presented visual categorial oddball shape discrimination task; in Exp 2 (Auditory-Attend), listeners attended to the auditory input and implicitly counted target deviants. MMN results showed effects of language experience and attentional focus: MMN amplitudes were smaller for American compared to Japanese listeners in the Visual-Attend Condition and for the American listeners in the Visual compared to Auditory-Attend Condition. Subtle differences in topography were also seen, specifically in that the Japanese group showed more robust responses than the American listeners at left hemisphere scalp sites that probably index activity from the superior temporal gyrus. Follow-up behavioral discrimination tests showed that Americans discriminated the contrast well above chance, but more poorly than did Japanese listeners. This pattern of electrophysiological and behavioral results supports the conclusion that early experience with phonetic contrasts of a language results in changes in neural representations in the auditory cortex that allow for more robust automatic, phonetic processing of native-language speech input.

Effects of Lips and Hands on Auditory Learning of Second-Language Speech Sounds

Previous research has found that auditory training helps native English speakers to perceive phonemic vowel length contrasts in Japanese, but their performance did not reach native levels after training. Given that multimodal information, such as lip movement and hand gesture, influences many aspects of native language processing, the authors examined whether multimodal input helps to improve native English speakers' ability to perceive Japanese vowel length contrasts. Sixty native English speakers participated in 1 of 4 types of training: (a) audio-only; (b) audio-mouth; (c) audio-hands; and (d) audio-mouth-hands. Before and after training, participants were given phoneme perception tests that measured their ability to identify short and long vowels in Japanese (e.g., /kato/ vs. /kato/). Although all 4 groups improved from pre- to posttest (replicating previous research), the participants in the audio-mouth condition improved more than those in the audio-only condition, whereas the 2 conditions involving hand gestures did not. Seeing lip movements during training significantly helps learners to perceive difficult second-language phonemic contrasts, but seeing hand gestures does not. The authors discuss possible benefits and limitations of using multimodal information in second-language phoneme learning.

Perception of Arabic and Japanese vowel length contrasts by native versus non‐native Japanese listeners.

The perception of short versus long vowel contrasts in Arabic and Japanese was examined for native Japanese [(NJ), n=5] and non‐native Japanese [(NNJ), n=5] listeners. The length contrast is phonemic in both languages. The question addressed was whether experience with Japanese helps NNJs to process the length contrast in Arabic. The listeners’ discrimination accuracy was assessed in an AXB test. The stimuli were CV1C words in Arabic and CV1CV words in Japanese (where V1 was either short or long). As expected, NJs were more accurate than NNJs in discriminating the Japanese contrast. While NJs made more errors in Arabic than Japanese, NNJs showed a similar level of discrimination accuracy for the two languages. Finally, the number of errors for the Arabic stimuli was comparable for NJs and NNJs. Thus, the between‐group difference existed for the Japanese but not for the Arabic contrast. The possibility that familiarity with phonetic characteristics of a recently acquired language may influence the processing of sounds in an unknown language with similar characteristics to the target language will be discussed. Native Arabic perception is currently under investigation. [Work supported by Macquarie University New Staff grant.]

Effects of hand gesture and lip movements on auditory learning of second language speech sounds

Previous research found that auditory training helps native English speakers to perceive phonemic vowel length distinction in Japanese, but that their performance has never reached native levels (Hirata et al., 2007). Given that multimodal information, such as hand gesture and lip movements, influences semantic aspects of language processing and development (Kelly et al., 2002), we examined whether this multimodal information helps to improve native English speakers' ability to perceive Japanese vowel length distinction. Forty-five native English speakers participated in one of three types of training: (1) audio alone; (2) audio with hand gestures; and (3) audio with lip movements and hand gestures. Before and after training, participants were given phoneme perception tests that measured their ability to distinguish between short and long vowels in Japanese, e.g., /kato/ versus /kato:/. Our original prediction was that more modalities in training would result in greater learning. Although all three groups improved from pre- to post-test, there were no significant differences among the three training groups. Unlike the original prediction, hand gestures and lip movements did not seem to augment learning of difficult sound distinctions. We will discuss possible benefits and limitations of using multimodal information in second language speech learning.

Training native English speakers to identify Japanese vowel length contrast with sentences at varied speaking rates

Native English speakers were trained to identify Japanese vowel length in three types of training differing in sentential speaking rate: slow-only, fast-only, and slow-fast. Following Pisoni and Lively's high phonetic variability hypothesis [Pisoni, D. B., and Lively, S. E., Speech Perception and Linguistic Experience, 433-459 (1995)], higher stimulus variability by means of training with two rates was hypothesized to aid learners in adapting to speech rate variation more effectively than training with only one rate. Trained participants identified the length of the second vowel of disyllables, short or long, embedded in a sentence of the respective rate, and received immediate feedback. The three trained groups' abilities before and after training were examined with tests containing sentences of slow, normal, and fast rates, and were compared with those of a control that was not trained. A robust effect of slow-fast training, a marginal effect of slow-only training, but no significant effect of fast-only training were found in the overall test scores. Slow-fast and slow-only training showed small advantages over fast-only training on the fast-rate test scores, while effects for all three training types were found on the slow- and normal-rate test scores. The degree to which the results support the high phonetic variability hypothesis is discussed.

Effects of training with sentences at varied speaking rates on native English speakers’ perception of Japanese vowel length

In training non-native speakers to perceive difficult second language (L2) phonetic contrasts, providing variation in speakers and phonetic contexts helps the formation of L2 categories [Pisoni and Lively, in Speech Perception and Linguistic Experience (1995), pp. 433–459. The present study tested the hypothesis that high stimulus variability in speaking rate would have positive effects for L2 learners. Native English speakers’ ability to identify Japanese vowel length was examined with three types of training: slow-only, fast-only, and slow-fast. Their perceptual abilities were measured with a pretest and posttest and compared with a control group that was not trained. Test stimuli were sentences containing Japanese disyllables spoken at three rates (slow, normal, fast). Participants were trained to identify the length of the second vowel of disyllables embedded in a sentence and they received immediate feedback. The pretest to posttest improvement of the slow-only (8.2%) and slow-fast (8.7%) training groups was significantly greater than the control group’s improvement (3.9%). However, the fast-only (7.7%) training group’s improvement did not significantly differ from the control group’s improvement. In addition, slow-fast training, unlike other training, had an advantage in performance on the fast rate stimuli. Implications for the variability theory will be discussed. [ Work supported by NSF Grant No. BCS0418246.]

Role of a carrier sentence in native speakers’ identification of Japanese vowel length

This study examined the role of word-external contexts in native speakers’ identification of phonemic vowel length in Japanese disyllabic nonwords. Three groups of native Japanese listeners (n=20, 20, and 19) were assigned to three conditions differing in word-external contexts. In intact condition, three types of target disyllables /mVmV/, /mV:mV/, and /mVmV:/ were spoken in a carrier sentence at slow and fast speaking rates. In the other conditions, the target disyllables of the intact condition were excised from the original carrier sentence (excised), and embedded in the carrier sentence of the other rate (mismatch). The accuracy for identifying the length of the two vowels was significantly higher for the intact (98.1%) than the excised (69.5%) and the mismatch condition (52.4%). This indicates that the presence of the carrier sentence with an appropriate rate was essential for accurate identification of vowels, consistent with Johnson and Strange [J. Acoust. Soc. Am. 72, 1761–1770 (1982)]. Further analysis indicated that the perceptual errors made in the excised and the mismatch conditions were closely associated with the absolute duration overlap between the short vowels spoken at the slow rate and the long vowels spoken at the fast rate.