Experimental results on voice prostheses used for the rehabilitation of patients that have lost their vocal function after total laryngectomy are presented. The purpose is to evaluate the difference in aerodynamic behaviour between Staffieri voice prosthesis and other commercial valves (Groningen standard, Groningen low pressure, Panje, Provox). Two different equipments for flow-rate measurement were designed and built to compare the performance of the valves. The valves have been experimentally tested under different conditions of airflow through the valve and tracheal side pressure. The data allow calculation of the airflow resistance, the parameter usually used to compare the performance of valves. The valves have also been experimentally tested under different conditions of fluid flow through the valve and oesophageal side pressure (reverse flow). Comparing the airflow resistance of Staffieri valves of different length L and different angular extension of the razor-thin silt alpha, it has been observed that the parameter alpha has a significant influence on the characteristics, while the effect of the length L is negligible. The airflow resistance of the Provox, Groningen low pressure and Staffieri alpha = 270 degrees valves are comparable; the Panje and Staffieri alpha = 180 degrees have similar behaviour; while the Groningen Standard is comparable to the Staffieri alpha = 90 degrees. Regarding reverse flow, it is pointed out that for most of the valves (Staffieri and commercial valves), at different oesophageal pressures the fluid flow is smaller than the flow that can be tolerated by patients without giving problems.