Phonatory valves are prostheses for the voice rehabilitation of patients that have lost the vocal function due to a total laryngectomy operation. The prosthesis is positioned in a fistula and recreates a communication via between the airway and the digestive tract, realising a one-way valve. In this paper the experimental results obtained with Staffieri and new tracheo-oesophageal prostheses are presented. The valves have been experimentally tested under different conditions of airflow through the valve and tracheal side pressure; the data have allowed to calculate the airflow resistance, the parameter usually used to compare the performance of valves. The valves have also been experimentally tested under different condition of fluid flow through the valve and oesophageal side dynamic pressure; the use of a dynamic pressure better reproduce the real functioning of the valve. Comparing the airflow resistance of the Staffieri and new tracheo-oesophageal prostheses with different angular extension of the razor thin slit a it has been observed that the parameter a has a significant influence on flow characteristics; while the influence of the shape of the hat is negligible for smaller a and became important for the bigger a considered. Regarding the reverse flow, it is pointed out that for most of the valve (Staffieri and new prosthesis), at different oesophageal pressures the fluid flow is smaller than the flow that can be tolerated by the patients without giving problems.

Index Terms. total laryngectomy, voice rehabilitation, voice prosthesis, voice button, phonatory valve, low resistance.