What is the definition or description of: acoustic reflectometry?

Sound wave: Acoustic reflectometry is a relatively new technique that quantifies upper airway obstruction. The basic physical principle is that an audible sound signal is generated at the bottom of a tubular probe (wave tube) and transmitted into the cavity examined via an anatomically fitted coupler (mouth or nose piece).

Sound wave: The device sends out a sound that bounces off the eardrum and then measures the eardrum's mobility. Normal movement generates "greater than 120". If there is fluid behind the drum dampening the movement the number can be as low as 40. It's a quick and easy measurement of middle ear fluid.