This study examines how the acoustic features of the Chinese Mandarin sibilant consonants [c], [s], and [s]and their following vowels in CV syllables function as perceptual cues. The author conducted speech perception experiments using speech morphing syntheses. The differences in perceptual cues weighting between native speakers of Japanese who learning Chinese Mandarin as a second language and Mandarin native speakers were also compared. Mandarin native speakers used both consonant and vowel part information as perceptual cues according to the Chinese phonological system, whereas the learners tended to be more influenced by the acoustic features of consonants.

A vowel identity can be determined by first two or three formants. Critical formant information includes a center steady state portion that are often called as “target” and preceding onglide and following offglide transitional movements. Dynamic, or transitional, information is closely related to the intrinsic duration of a vowel. For example, tense and lax vowels of English have different characteristics of onset and offset transitions. The question of the present research is: does the transitional information of vowel offset affect perceptual duration of a vowel in general? The study compares perceptual duration of a steady state formant followed by a rapid and less rapid formant transitions using synthetic VCV syllables. Our experiment provides foundations to discuss how the perceptual duration of a vowel varies before a rapid and less-rapid transitions.

Adult foreign language learners are likely to retain a discernible accent, however fluent they may otherwise become. It is therefore important to understand the nature of foreign accents and their consequences. Prior work on second-language Japanese has shown that non-native pitch patterns robustly predict the perception of accent. Whereas speaker and speech factors are critical factors affecting perceived foreign accents, listener factors also play a not insignificant role. This paper reviews prior work and discusses the directions that future research may take to deepen understanding of foreign accents in Japanese.

"Bi/multilingual" is often used to describe people who are fluent in more than one language, but this does not mean such people can remain so unconditionally. Many suffer from the loss of acquired language due to various environmental changes after their prolonged status as returnees, upon returning from study abroad, or domestic educational background. This paper observes the language items reported as lost in a questionnaire survey on language loss among multilingual people. We also analyze measures to prevent language loss and uncover clues to factors that make acquisition difficult for second language learners. "Loss after language acquisition" refers to long-term loss, which is when a person cannot use a particular language more fluently than before. Many of the survey respondents indicated they noticed a difference in the ease of use between languages and that some languages were being lost to them. Since some of the language items in the survey showed characteristics related to language loss, we will focus on factors related to language loss and the process of language acquisition.

The present study aimed to reveal how speech and behavioral characteristics of mother and infant during their interaction in early development affect later working memory capacity of infant. For this purpose, we examined correlations between video coding data of still face paradigm at infant's age of 6 month and their score of working memory task at 2 years and 3 years-old using data set of our longitudinal study. We further examined differences between typically developing infants and infants at risk for autism spectrum disorder (ASD). The participants were 31 dyads of infant (boys = 16) and mother. Among them, 15 infants were infants at-risk for developmental disorder (siblings of ASD).

For behavioral and speech indices of mother and infant interaction, we video-coded vocalization, touching behavior and rhythmic movement in mothers and infants. Correlation coefficients were examined between these indices and infants' score of working memory tasks including digit span and sentence repetition task using Kyoto developmental scale. Results showed some significant correlations. For instance, duration of mother's speech during interaction was positively correlated with infant's later performance of digit span task. The number of rhythmic utterances by mother and infant positively correlated with the performance of sentence repetition task. These results suggested that mother's communicative behaviors including speech at the early stage of development influence the development of working memory including verbal short-term memory. Keywords infancy, mother-infant interaction, working memory.