Production of various vocal cord vibrations using a mechanical model for an anthropomorphic talking robot

We developed a three-dimensional mechanical vocal cord model for Waseda Talker No. 7 (WT-7), an anthropomorphic talking robot, for generating speech sounds with various voice qualities. The vocal cord model is a cover model that has two thin folds made of thermoplastic material. The model self-oscillates by airflow exhausted from the lung model and generates the glottal sound source, which is fed into the vocal tract for generating the speech sound. Using the vocal cord model, breathy and creaky voices, as well as the modal (normal) voice, were produced in a manner similar to the human laryngeal control. The breathy voice is characterized by a noisy component mixed with the periodic glottal sound source and the creaky voice is characterized by an extremely low-pitch vibration. The breathy voice was produced by adjusting the glottal opening and generating the turbulence noise by the airflow just above the glottis. The creaky voice was produced by adjusting the vocal cord tension, the sub-glottal pressure a...