A voice-producing prosthesis for laryngectomized patients

Despite state of the art tracheo-esophageal (TE) voice-rehabilitation after laryngectomy, some patients are unable to produce voice of sufficient quality, because of hypotonicity or atonicity of their pharyngoesophageal (PE) segment. Furthermore, the TE voice is low pitched, which presents a problem especially for female laryngectomized patients. A voice-producing element (VPE) is developed, based on the double membrane concept, to supply the laryngectomized patients with a better substitute voice. The VPE is comprised of two elastic membranes inside a circular housing that can be inserted in a shunt valve. Four identical prototypes were manufactured and tested in-vitro under physiological conditions. Prototypes were also tested in 17 female laryngectomised patients. An aerodynamic and acoustical analysis was performed, the maximum phonation time, speech rate and intonation capability determined. Finally the voice was perceptual evaluated. Basic sound, containing multiple harmonics, was successfully produced under physiologic air pressure and airflow conditions. The fundamental frequency and sound pressure level could be controlled by changing the driving pressure, thus enabling sufficient intonation. The obtained frequency range (190-350 Hz) is appropriate for producing a female voice. The VPE produced a sound with a low noise-to-harmonics ratio (mean 0.15), the efficiency of sound production (5.5?10^-5) is comparable to normal vocal folds. The clinical study clearly showed that the pitch and sound intensity were increased without an unacceptable increase in driving lung pressure. The flow rates were lower than normal, leading to significantly longer phonation times. Accumulation of mucus did not interfere with speech production. In conclusion, functional restoration of the voice after laryngectomy with a VPE, based on the double-membrane concept, appears a feasible concept for female laryngectomized patients or patients with a hypo- or atonic PE segment.