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2. 2) M. Fujimoto and S. Kiritani, ``Comparison of vowel devoicing for speakers of Tokyo- and Kinki dialects,'' J. Phon. Soc. Jpn., 7(1), pp. 58-69 (2003) (in Japanese).
3. 3) M. Sugito, The Sounds of Japanese (Izumishoin, Osaka, 1996) (in Japanese).
4. 4) NHK Broadcasting Culture Research Institute, The Japanese Language Pronunciation and Accent Dictionary (NHK Publishing, Tokyo, 1998) (in Japanese).
5. 5) I. Konishi, ``Research approach for dialects in new age,'' in Research Methods in Dialectology, T. Kobayashi, Ed. (Iwanamishoten, Tokyo, 2007), pp. 1-38 (in Japanese).