Acoustic interferometer

An acoustic interferometer is an instrument for measuring the physical characteristics of sound waves in a gas or liquid. It may be used to measure velocity, wavelength, absorption, or impedance. A vibrating crystal creates the ultrasonic waves that are radiated into the medium. The waves strike a reflector placed parallel to the crystal. The waves are then reflected back to the source and measured.

*This article is licensed under the |GNU Free Documentation License. It uses material from the Wikipedia article http://en.wikipedia.org/wiki/Acoustic_interferometer