Measurement of volume velocity of a small sound source

Two methods for measuring volume velocity of a back-enclosed driver, that make no assumptions about the shape or the vibration distribution of the driver’s diaphragm, are investigated: a compression chamber and a blocked pipe. Both methods were implemented on an off-the-shelf driver using a microphone installed in the driver’s cavity. The relationship between the pressure inside of the driver’s cavity and the volume velocity of the driver’s diaphragm was established by measurement. The two methods produced similar results.