The Mastery Evaluation Using Singing Learning Support System based on the Visualization of Acoustic Features of Learners’ Singing Voice. Association for the Advancement of Computing in Education (AACE) , In Proceedings of E-Learn: World Conference on E-Learning in Corporate, Government, Healthcare, and Higher Education 2015 , :pp.1981-1985 2015(Oct.) Author:Ikeda, Kyoko., Haga, T., Kayama, M., Itoh, K., et al.