Clear speech effect on vowel production across languages

Abstract

In this talk, we discuss vowel production in clear speech, a distinct mode of speech production intended to enhance intelligibility, across languages with different phonological properties (Croatian and Spanish with small vowel inventories vs. English with a large vowel inventory). A comparison of Croatian and English revealed the equivalent clear speech vowel space expansion in both languages. In addition, listeners recognized words in noise more accurately in clear than in plain speech in their native language, establishing that the plain-to-clear speech articulatory modifications increased intelligibility. A comparison of Spanish and English also showed similar amounts of vowel space expansion as well as the maintenance of coarticulatory patterns in clear speech for both languages. The inventory-independent vowel space expansion in all three languages suggests that talkers hyperarticulate even when segments are unlikely to be perceptually confusable (few vowel categories that are fairly distinct). The maintenance of coarticulation further suggests that spreading of segment identity across neighboring sounds may be beneficial to the listener. In this talk, we also discuss various measures of vowel space expansion and different clear speech strategies across talkers. We conclude with some remarks about the link between the identified acoustic-phonetic features of clear speech and intelligibility.