Patent ID: 8176789

Claim:
An apparatus for measuring the sound intensity emitted by a vibrating surface, comprising: a probe having a straight supporting tube with only three microphones attached perpendicularly to the outside of the supporting tube, the microphones being positioned in line, in the side-by side arrangement; wherein said three microphones are labeled respectively with the numbers 1 , 2 and 3 , starting from the microphone closest to said vibrating surface and moving outward away from the surface; wherein sound pressure is measured using respectively the pair of microphones 1 and 2 , or the pair 1 and 3 , or the remaining pair 2 and 3 ; wherein an electronic switch changes sound-pressure measurements back and forth between the microphone pair 1 and 2 and the microphone pair 1 and 3 ; instrumentation for amplifying the sound pressure measured by said microphones and for conducting the measurements to a computer; a computer program for determining sound-intensity spectra and sound intensity using the cross-spectral relation; a device connected to said computer for displaying sound pressure, sound-intensity spectra and sound intensity.