Predicting gradation of L2 English mispronunciations using ASR with extended recognition network

A CAPT system can be pedagogically improved by giving effective feedback according to the severity of mispronunciations. We obtained perceptual gradations of L2 English mispronunciations through crowdsourcing, conducted quality control to filter for reliable ratings and proposed approaches to predict gradation of word-level mispronunciations. This paper presents our work on making improvements using ASR with extended recognition network to the previous predicting approach to solve its limitations: 1. it is not working for those mispronounced words whose transcriptions are not immediately available; 2. perceptually differently articulated words with the same transcription have the same predicted gradation.