Ryoko Hayashi

Assessing cerebral representations of short and long vowel categories by NIRS.

&NA; The present study examined cerebral representations of Japanese long and short vowel categories with near‐infrared spectroscopy (NIRS) by measuring the hemodynamic changes. Results showed that NIRS could capture phoneme‐specific information. The left side of the auditory area showed large hemodynamic changes only for contrasting stimuli between which the phonemic boundary was estimated, but not for stimuli differing by an equal duration but belonging to the same phoneme category. Left dominance in phoneme processing was also confirmed for the across‐category stimuli. These findings indicate that the Japanese vowel contrast based only on duration differences is dealt with in the same language‐dominant hemisphere as other spectrally varying phonemic categories, and that the cortical activities related to its processing can be detected with NIRS.

Elicitation of N400m in sentence comprehension due to lexical prosody incongruity

The role of lexical prosody in the semantic integration of spoken sentences consisting of a quiz stem and an answer word was investigated analyzing the event-related magnetic response, N400m. Three conditions regarding the relations between the quiz and the answer word were prepared: pitch–accent violation, phonemic violation and no violation. Both the pitch–accent and phonemic violations elicited significant N400m without any significant differences in the peak latency and magnitude of the equivalent current dipoles, suggesting that the role of pitch–accent in semantic integration is equivalent to that of phonemes. However, the rate of violation detection and the successful N400m source estimation were lower for the pitch–accent violation than for the phonemic violation, suggesting differential neural processes for the phonemic and prosodic cues.

Production and reproduction of Japanese pitch-accent by German, Italian, Vietnam, and Swahili speakers

Japanese pitch accent is lexically distinctive. JFL learners should know the position of the accent to pronounce the words correctly, which is said to be very difficult. In our experiment, we investigate the effectiveness of showing the accent mark to help learners’ pronunciations. We compared the ability of perception, production and reproduction of pitch accent by JFLs of four different languages. 42 Japanese words were presented on a PC screen and 30 subjects participated in three tasks of the experiments. Task 1 was to pronounce the words without any suggestion, task 2 was to imitate the model pronunciation with seeing the accent marks. Task 3 was to pronounce by just seeing the accent marks. The results of task 1 show the percentage of correct accent position was only around 40%, but it rose up to around 90 % in task 2 and fell again in task 3 but still significantly higher than in task 1. The results of task 1 showed different patterns of phonetic interference, task 2 showed that the subjects could ...

Providing new methods for teaching Japanese speech communication for learners of Japanese as L2: Developing teaching materials using MRI‐movies and natural speech data

It is critical to provide people learning Japanese as a second language information about natural speech, since there is wide variability of articulation and speaking styles associated with various social attitudes and/or expressions in Japanese. For developing teaching materials for English and Chinese learners of Japanese as a second language, two new methods are demonstrated. One utilizes MRI‐movies that dynamically demonstrate differences among vowel articulations in Japanese, English, and Chinese. This approach is effective for teaching good pronunciation, especially with regard to consonant cluster production, since the timing of the articulation for consonant clusters is visibly presented. The other is audio‐visual data of natural speech in Japanese that demonstrate several typical expressions, e.g., wry face and strained (laryngealized) voice for asking favors politely. This type of material shows not only variations of speech communication in Japanese but also cultural differences among native sp...

Cerebral responses to across‐ and within‐category change of vowel durations measured by near‐infrared spectroscopy

The present study examined cerebral responses to phoneme categories, using near‐infrared spectroscopy (NIRS) by measuring the concentration and oxygenation of hemoglobin accompanying local brain activities. Targeted phonemes used here are Japanese long and short vowel categories realized only by durational differences. Results of NIRS and behavioral test revealed NIRS could capture phoneme‐specific information. The left side of the auditory area showed large hemodynamic changes only for contrasting stimuli between which phonemic boundary was estimated (across‐category condition), but not for stimuli differing by an equal duration but belonging to the same phoneme category (within‐category condition). Left dominance in phoneme processing was also confirmed for the across‐category stimuli. These findings indicate that the Japanese vowel contrast based only on duration is dealt with in the same language‐dominant hemisphere as the other phonemic categories as studied with MEG and PET, and that the cortical ac...