Kitahara Mafuyu

Functional load of pitch accent is proposed for Japanese words. It is calculated from 1) the ratio of the number of a pair of homophones with opposing pitch accent to the number of those with non-opposing pitch accent, and 2) word familiarity of the homophones. The functional load is larger when the difference of word familiarity scores is smaller between homophones with opposing pitch accent. The statistical characteristics of the functional load of pitch accent were analyzed using a large-scale word familiarity databases of Japanese.

Pitch accent realization requires voicing. However, high vowels are sometimes devoiced even though the vowel carries a pitch accent in Tokyo Japanese. This devoicing, then, would obliterate the pitch accent were it not for other effects which preserve the accent information. Previous studies showed that there is either a pitch raising after the devoiced region or an accent shift to nearby moras in those cases. Two production experiments were conducted to see how various conditions, such as tonal context, boundary location, and syllabic environment, affect the pitch accent preservation. Results show that accent shift is strictly governed by the boundary and syllabic conditions but pitch raising does not always make up for the lack of accent shift. Accent location information is lost in such cases where neither pitch raising nor accent shift occurs. This suggests a relatively lower functional load of accentual contrast in Japanese.