What is a voice prosthesis?

The voice prosthesis is made of synthetic materials, about 1-2 centimetres in diameter, and it works as a valve. Air can travel through the windpipe to the oesophagus and throat cavity, but food cannot travel from the oesophagus to the windpipe. The air travelling through the valve into the oesophagus, vibrates the oesophageal mucosa.   Vibration is sound, generating a voice sound.