Effects of speaking style on the regularity of mora timing in Japanese

The regularity of mora timing in Japanese has remained controversial over the years [Warner and Arai, Phonetica 58, 1–25 (2001)]. It is possible that the degree of regularity varies with speaking style. Four Japanese subjects spoke six‐mora proper names with varying syllable structures where the second name had either three simple syllables (e.g., Tomiko) or two syllables with a long vowel (e.g., Tooko) or a long consonant (e.g., Tokko). These were read either in formal sentences, read in conversational style sentences, or used in spontaneous description of pictures of characters having these names. Moras were measured as the intervals between vowel onsets using an automatic vowel‐onset detection algorithm. Although all styles suggested regular mora timing, the results show that the styles differ in the degree of temporal compensation for the moras constituted by long vowels and long consonants which are shorter than consonant‐vowel syllables. The compensation was clearest in the most formal style of speech.