A study on respiratory and glottal controls in six western singing qualities: airflow and intensity measurement of professional singing. - Jo Estill; Noriko Kobayashi; Kiyoshi Honda; Yuki Kakita (ICSLP, 1990)

Aperiodicity extraction and control using mixed mode excitation and group delay manipulation for a high quality speech analysis, modification and synthesis system STRAIGHT. - Hideki Kawahara; Jo Estill; Osamu Fujimura (MAVEBA, 2001)