Influence of preceding speech on the initial vowel quality of laughter in spontaneous conversation

This study examined how the final phone of speech preceding laughter affects the vowel quality of laughter onsets. We analyzed 473 laughter instances extracted from 16 h of spontaneous Japanese conversation. The analysis focused on the final syllable of the speech immediately preceding the laughter and the first call of the laughter, categorizing vowel quality into the five Japanese vowels (/a, i, u, e, o/) and schwa. The results showed that when the final syllable of the preceding speech ends in high vowels /i/ or /u/, there is a strong influence on the initial vowel quality of the laughter, often resulting in a matching high vowel in the laughter onset. In addition, when the first call of laughter is schwa, it is more frequently preceded by speech ending in the vowel /a/. These findings suggest that carryover coarticulation at the speech–laughter boundary plays a role in shaping the acoustic characteristics of laughter, which also provides evidence for the articulatory continuity across speech and nonverbal vocalization in spontaneous interaction.