Was That a Bag or a Bug? Perceptual Measures, Euclidean Distance, Mahalanobis Distance, and Pillai Scores in the Assessment of L2 Pronunciation

Abstract

[eng] Researchers employ a variety of techniques to measure accuracy of second-language pronunciation. Little research has been done on certain measures that have been used more in recent studies, such as Mahalanobis distance and Pillai scores, and how they compare to perceptual measures. Using pre- and post-test recordings of 23 Spanish/ Catalan learners of English that were obtained using a delayed word repetition task in a previous, high-variability phonetic training study on the English phonemes /æ/ and /ᴧ/, this thesis examines the relationship between native-speaking judges’ word identification and goodness ratings, Euclidean distances, Mahalanobis distances, and Pillai scores in their evaluation of pronunciation accuracy and improvement between test times. For each acoustic metric, measures between native- and non-native speakers’ productions are taken as well as measures between non-native speakers’ realizations of /æ/ and /ᴧ/. An experimental way of computing perceptual ratings for items that are incorrectly identified by raters is also investigated and compared to existing measures.