Measuring Foreign Accent Strength in English

Abstract

With an eye toward measuring the strength of foreign accents in American English, we evaluate the suitability of a modified version of the Levenshtein distance for comparing (the phonetic transcriptions of) accented pronunciations. Although this measure has been used successfully inter alia to study the differences among dialect pronunciations, it has not been applied to studying foreign accents. Here, we use it to compare the pronunciation of non-native English speakers to native American English speech. Our results indicate that the Levenshtein distance is a valid native-likeness measurement, as it correlates strongly (r = -0.81) with the average “native-like” judgments given by more than 1000 native American English raters.

Computational Sociolinguistics: A Survey

“…Crowdsourcing has already been used to obtain perception data for sociolinguistic research, for example, to study how English utterances are perceived differently across language communities (Makatchev and Simmons 2011) and to obtain native-likeness ratings of speech samples (Wieling et al 2014). For some studies, games have been developed to collect data.…”

A New Acoustic-Based Pronunciation Distance Measure

“…The native American-English speakers who rated the non-native speech samples also had different regional backgrounds. The data we include in this study is similar to the data used for evaluating a transcription-based measurement in the study of Wieling et al (2014). As in some cases a word was produced twice by a speaker, or two words were merged into one word, we removed duplicate words from the speech samples by deleting one of the repeated words, and merged words were split such that each speech sample consisted of 69 separate words.…”

“…Perceptual data have been widely used to assess the degree of foreign-accentedness (Koster and Koet, 1993;Munro, 1995;Magen, 1998;Munro and Derwing, 2001). We therefore use human judgments of native-likeness that were collected in the study of Wieling et al (2014). They created an online questionnaire in which native speakers of American-English were asked to rate the accent strength of 50 speech samples extracted from the Speech Accent Archive.…”

“…The questionnaire of Wieling et al (2014) was distributed by asking colleagues and friends to forward it to native speakers of American-English. The questionnaire was also mentioned in a blog post of Mark Liberman 1 which led to a considerable amount of responses.…”

“…The primary goal of this study is therefore to develop an improved acoustic pronunciation distance measure that computes pronunciation distances without requiring phonetic transcriptions. To assess whether the acoustic distance measure is a valid measurement technique to measure accent strength (compared to native speakers), we compare the acoustic distances to a collection of human native-likeness judgments that were collected by Wieling et al (2014) to evaluate a phonetic transcription-based method. The core of the acoustic distance measure is to use dynamic time warping (DTW) to compare non-native accented American-English to native-accented American-English speech samples represented as Mel-frequency cepstral coefficients (MFCCs).…”