ASA 126th Meeting Denver 1993 October 4-8

4pEA10. Effect of microphone placement on adaptive noise cancellation methods with machine ball bearing measurements to detect bearing flaws in reverberant environments.

Matthew S. Carney J. Adin Mann, III

Dept. of Aerosp. Eng. and Eng. Mech., Iowa State Univ., Ames, IA 50010

Sound measurements on operating machinery in reverberant environments are difficult to analyze. Adaptive noise algorithms [C. C. Tan, IECON, 703--708 (1985)] are available to reduce the amount of background noise in the measured data. Due to the reverberation of the environment, proper placement of the microphones is important to achieve the greatest noise cancellation from the algorithm. Measurements were taken on bearings with known flaws under different loads and speeds. Results of these measurements will show the effectiveness of sound pressure measurements, and sound intensity measurements, to detect bearing flaws with the help of the adaptive noise cancellation algorithm when the microphones are properly placed.