The degree and time course of nasal coarticulation across communicative contexts: A study of the LUCID corpus

Abstract

We analyzed the degree and time course of coarticulatory vowel nasalization in hyperarticulated clear speech produced in real and imagined communicatively challenging conditions from the LUCID corpus (Baker & Hazan, 2011). Southern British English speakers completed an interactive spot-the-difference task in pairs when there was no overt communication barrier (NB), when the partner was non-native (L2), and when one speaker’s speech was vocoded (VOC) or mixed with talker babble (BABBLE). They also read sentences conversationally (READ-CO) and clearly (READ-CL). The results showed significantly greater overall keyword vowel nasalization in the BABBLE and L2 conditions than in NB, READ-CO, and READ-CL, as well as in VOC than in NB and READ-CO. READ-CL and READ-CO did not differ significantly. Examining vowel nasalization over time revealed that the significant differences emerged, on average, at 7.4% into the vowel. Speakers increased coarticulatory nasalization early in the vowel when producing hyperarticulated speech in response to a real communicative barrier, consistent with the idea that nasal coarticulation facilitates speech processing by cueing upcoming segments. It remains to be determined why nasal coarticulation is increased while coarticulation for other consonant-vowel sequences is decreased during the production of hyperarticulated listener-oriented speaking styles (Guo and Smiljanic, 2021).