Foreign accent conversion in computer assisted pronunciation training

Abstract

Learners of a second language practice their pronunciation by listening to and imitating utterances from native speakers. Recent research has shown that choosing a well-matched native speaker to imitate can have a positive impact on pronunciation training. Here we propose a voicetransformation technique that can be used to generate the (arguably) ideal voice to imitate: the own voice of the learner with a native accent. Our work extends previous research, which suggests that providing learners with prosodically corrected versions of their utterances can be a suitable form of feedback in computer assisted pronunciation training. Our technique provides a conversion of both prosodic and segmental characteristics by means of a pitch-synchronous decomposition of speech into glottal excitation and spectral envelope. We apply the technique to a corpus containing parallel recordings of foreign-accented and native-accented utterances, and validate the resulting accent conversions through a series of perceptual experiments. Our results indicate that the technique can reduce foreign accentedness without significantly altering the voice quality properties of the foreign speaker. Finally, we propose a pedagogical strategy for integrating accent conversion as a form of behavioral shaping in computer assisted pronunciation training.

The Voice Conversion Challenge 2016

“…To develop this technique, we need a deep understanding of how to effectively factorize speech acoustics into its individual components such as linguistic, non-linguistic, and para-linguistic information using various technologies, such as speech analysis, speech synthesis, acoustic modeling, and machine learning. Moreover, VC has great potential to develop various applications not only for flexible control of speaker identity of synthetic speech in textto-speech (TTS) [1] but also as a speaking aid for vocally handicapped people such as dysarthric patients [2] and laryngectomees [3], as a voice changer to flexibly generate various types of emotional [4] and expressive speech [5], for vocal effects to produce more varieties of singing voices [6,7], for enhanced mobile speech communication using wideband speech [8] and silent speech [9], accent conversion for computer assisted language learning [10], and so on. Therefore, it is worthwhile to study this technique for both scientific purposes and industrial applications.…”

Native Speakers' Perception of Non - Native English Speech

“…Finally, Felps, Bortfeld & Osuna (2009) stated that foreign accent can be a deviation from the expected acoustic and prosodic norms of language.…”

Accent rating by native and non-native listeners

“…Accent rating-the degree of foreign accent or type of accent of a talker-is a perceptual evaluation task that is relevant to a variety of different tasks within speech technology, e.g., in computer assisted language learning [1,2], for accent conversion [3,4], for accent identification [5,6], to reduce the impact of non-native accents on word error rates in ASR [7,8], and in the context of adverse listening conditions [9]. The study presented here was conducted in the context of an EU project which aimed for personalized speech-to-speech translation such that a user's spoken input in one language was used to produce spoken output in another language, while continuing to sound like the user's voice [10].…”