Pitch Pattern Recognition of Isolated Words for the Development of a Japanese Language Call System

A language learning system for guiding a student on how to pronounce words of a second language must provide meaningful feedback while locating the learner’s errors with a high accuracy. We propose a method to detect pitch accent errors in the speech of learners of Japanese. In previous methods, Tokyo accent type recognition of the learner utterance was focused on. However, the learner may produce pitch patterns outside of these accent types so it is necessary to be able to identify all possible pitch level combinations. This paper presents a technique to identify all patterns. Employing either a 2 mora model or a 3 mora model, this method identifies pitch level for contiguous two or three mora unit sets. Then it determines the most likely combination of these units to determine the pitch level pattern of the word. Through this method we achieved a 93.4% correct pitch level identification rate at the mora level.