New excitation codebook search methods to reduce perceptual degradation of CELP. - Tadashi Yamaura; Hirohisa Tasaki; Shinya Takahashi (Syst. Comput. Jpn., 2007)

Intelligibility improvement of bandlimited synthesized speech by superposing high frequency component of input signal on baseband signal. - Satoru Furuta; Tadashi Yamaura (GCCE, 2014)