Tongue root positioning in English voiced obstruents: Effects of manner and vowel context

Abstract

Previous research on utterance-initial voiced stops in American English (AE) has shown that speakers enlarge the vocal cavity via tongue root advancement whether or not the stop is phonated when compared to voiceless stops (Ahn 2015). The current ultrasound study expands this line of research to examine two further variables: (a) utterance-initial fricatives/affricates and (b) effect of frontness of the following vowel. Participants included both monolingual (n = 4) and simultaneous bilingual (n = 7) AE speakers. Phrase-initial stops (/p,b,t,d,k,g/), fricatives (/f,v,s,z/), and affricates (/tʃ,ʤ/) were followed by /e/ or /u/. Most productions confirmed that both phonated and unphonated voiced stops/affricates had more tongue root advancement than voiceless ones, but a small proportion showed no difference between phonated, unphonated, and voiceless stops/affricates. Fricative productions were divided between no tongue root difference due to either voicing or phonation, and greater advancement for voiced fricatives regardless of phonation. Tongue root advancement may be less prevalent for fricatives because weakening of the frication can also facilitate the conditions for phonation. A prediction that tongue root advancement for voicing before /e/ might be limited by the positioning requirements of the front vowel was weakly supported, especially for fricatives. The potential effects of bilingual speakers are also addressed.