Effects of Acoustic Variability in the Perceptual Learning of Non-Native-Accented Speech Sounds

Abstract

This study addressed whether acoustic variability and category overlap innon-native speech contribute to difficulty in its recognition, and more generallywhether the benefits of exposure to acoustic variability during categorizationtraining are stable across differences in category confusability. Three experimentsconsidered a set of Spanish-accented English productions. The set was seen topose learning and recognition difficulty (experiment 1) and was more variable andconfusable than a parallel set of native productions (experiment 2). A trainingstudy (experiment 3) probed the relative contributions of category central tendencyand variability to difficulty in vowel identification using derived inventoriesin which these dimensions were manipulated based on the results of experiments1 and 2. Training and test difficulty related straightforwardly to category confusabilitybut not to location in the vowel space. Benefits of high-variability exposurealso varied across vowel categories, and seemed to be diminished for highly confusablevowels. Overall, variability was implicated in perception and learning difficultyin ways that warrant further investigation.