Published online by Cambridge University Press: 21 January 2021
Accents in second language speech have multiple perceptual consequences, including breakdown in communication and undesirable judgments about accented speakers. Whereas perceived accents are likely influenced by various acoustic variables, it is not clear which acoustic variables influence the perceived accents the most and whether such important predictors of accents change as learners’ proficiency develops. Here we report a study that has examined acoustic sources of foreign accent in second language Japanese produced by American learners at different instructional levels, including beginning and intermediate late learners and early bilinguals. We collected speech samples from these learners as well as a control group of native speakers and measured 27 segmental and prosodic variables. These acoustic variables were related to accent rating scores obtained from native listeners. Confirmatory analyses showed that 24 out of 27 variables tested were reliably associated with listeners’ accentedness judgements. Exploratory analyses showed that prosodic features were most predictive of beginning to intermediate late learners’ accents, whereas vowel features were most predictive of early bilinguals’ accents. These results shed light on issues related to the acoustic sources of foreign accent and the development of second language speech.