Acoustic characteristics of intervocalic stop lenition in American English

Abstract

Descriptions of English and other languages have claimed that intervocalic stops are often lenited to fricatives or approximants in connected speech, but few acoustic analyses of factors that affect lenition have been reported for American English [cf. Lavoie (2001)]. In this analysis, intervocalic voiced stops produced in bi- and trisyllabic words during story reading are examined (participants N = 14). The first result shows that American English speakers never lenite to fricatives, but rather produce approximants whenever lenition occurs. Second, stress plays an essential role: 51% of stops are lenited when stress is on the first syllable (e.g., “yoga”), but only 7% of stops lenite when stress is on the second syllable (e.g., “begin”). Overall, approximant productions are significantly higher for /d/ (which becomes a flap--63%) and /g/ (70%) as compared to /b/ (43%). For both stress placements, stop productions are longer and lower in intensity than approximant productions. Another significant factor is frequency, as higher frequency words are produced as approximants more often. These acoustic findings are generally consistent with Kingston’s (2006) claim that lenition within words and phrases occurs to minimize interruptions to the prosodic unit and indicate that the current constituent is ongoing.