Statistical studies on Japanese sonority by using loudness calibration scores

This study aimed to examine Japanese sonority by using a quantitative method and contribute to Japanese phonetics and phonology. Thus, loudness calibration scores from the NTT-Tohoku University Speech Dataset for a Word Intelligibility Test based on Word Familiarity (FW03) were analyzed. The intensity of each monosyllable sound stored in FW03 was equalized, and thus, perceptual sound levels varied with the difference in the original sound intensity of syllables. To adjust the difference in perceptual sound levels, calibration scores were estimated using a series of psychometric experiments. These scores reflected the difference in sound intensity and perceptual levels and can be considered subjective sonority scores for Japanese monosyllables. The results of the statistical analysis of the scores revealed that the sonority level of Japanese vowels was primarily accounted for its openness. The sonority of consonants was affected by its articulation and voicing, whereas that of monosyllables can be clustered based on the openness of vowels.