This study examines the difference in phonetic characteristics of Japanese polite speech by Japanese native speakers and Chinese-speaking learners. In the production experiment, subjects were asked to produce requests with different levels of psychological imposition. As a result, utterances with high imposition by native speakers showed slower speech rate, narrower F0 range, and lower F0 max. Furthermore, prolongation and pressed voice which indicates disfluency, as well as the use of breathy voice were demonstrated. In contrast, the utterance of Chinese-speaking learners showed different intonation patterns. However, in the perception experiment, there was little difference between native speakers and Chinese-speaking learners.

In Miyako Ryukyuan, nasal consonant sequences occur at the beginning of words. One of its dialects, Ikema, features voiceless nasal sounds characterized by frication noise. This study examined the articulation of nasal consonants in Ikema using real-time MRI data from two speakers. The study found that the nasal consonant sequence starting with a voiceless nasal [m̥m] (voiceless [m] followed by voiced [m]) has a larger oral cavity area and that the sequence starting with [n̥n] (voiceless [n] followed by voiced [n]) has a greater degree of velum lowering than their voiced counterparts. Either of these factors could intensify the airflow noise. The tongue position of the word-final /n/ tends to assimilate to that of the preceding vowel, which is a shared feature with standard Japanese, as recently reported.

The present study investigated whether the articulation ability and speech rate control of people who stutter (PWS) were different from people who do not stutter (PWNS). Twenty PWS and 20 PWNS performed oral reading and speech shadowing. Speech and articulation rates and, the number and duration of pauses were analyzed. PWS showed slower articulation rates with more pauses than PWNS during oral reading, but not during speech shadowing. This suggests that PWS control speech differently under the two conditions. Furthermore, PWS showed a significant negative correlation between articulation rate and number of pauses during oral reading.