Sizing of replacing voice Tracheoesophageal and esophageal voice production have in common that the PE segment is the sound source, but they do differ in the air supply to this source. Conventional esophageal voice is obtained by injecting relatively small amounts of air (60-80 ml) from the mouth into the esophagus and redirecting this column of air upwards through the PE segment. Prosthetic voice production, however, like normal laryngeal voicing, is pulmonary driven. Much like the vocal fold mucosa in laryngeal voicing, the PE segment mucosa is vibrating and mucosal waves can be seen with high-speed digital imaging during such voicing (Van As et al., 1999). Speech and voice therapy in TEP prosthetic speakers, therefore, resembles normal laryngeal voice training.