Development of a prosodic reading tutor of Japanese - effective use of TTS and F0 contour modeling techniques for CALL

A text typed to a speech synthesizer is generally converted into its corresponding phoneme sequence on which various kinds of prosodic symbols are attached by a prosody prediction module. By using this module effectively, we build a prosodic reading tutor of Japanese, called Suzuki-kun, and it is provided as one function of OJAD (Online Japanese Accent Dictionary) [1]. In Suzuki-kun, by using a prosody prediction module, any Japanese text is converted into its reading (Hiragana sequence) on which the pitch pattern that sounds natural is visualized as a smooth curve drawn by the F0 contour generation process model [2]. Further, positions of accent nuclei and unvoiced vowels are illustrated. Suzuki-kun also reads that text out following the prosodic features that are visualized. Since releasing Suzuki-kun, the number of accesses to OJAD has been drastically increased and for the last four months, OJAD received 129,168 accesses, 58.9 % of which were from outside Japan.