Experiments in surgical voice restoration using valve prostheses.

As our experience with 132 laryngectomees shows, the quality of tracheopharyngeal speech differs. Effortless tracheo-pharyngeal speech requires low flow resistance. Testing the individual factors that influence flow resistance and which are due to the prosthesis, we found that prosthesis diameter and slit length were most important. Various types of valve prosthesis differ considerably in their flow resistance. However, a low-flow resistance valve prosthesis is only partly responsible for easy phonation: Contact between the pharyngeal end of the prosthesis and surrounding tissue may influence voice quality considerably. A later paper will describe the extent to which surgery can create a low-resistance vibratile upper digestive tract.