Pressure Controlled Valves

Returning now to our model of wind instruments....

Blowing into an instrument mouthpiece creates a pressure difference across the surface of the reed.

When the reed oscillates, it creates and alternating opening and closure to the bore, allowing airflow entry during the open phase and cutting it off during the closed phase.

The effect, is often seen as a periodic train of pressure pulses into the bore.

Sound sources of this kind are referred to as pressure-controlled valves and they have been simulated in various ways to create musical synthesis models and vocal systems.