Noise source contribution analysis by Laser Doppler Vibrometer and sound intensity probe

The Selective Intensity technique is a powerful tool for understanding the vibro-acoustic interactions in a mechanical system. The method is based on transfer functions calculation between the structural vibration and the acoustic emission of the object under test. An innovative procedure has been previously developed by the authors combining a Laser Doppler Vibrometer (LDV) and a sound-intensity probe measuring simultaneously on the same point. In this paper an application of this technique on a epicyclical gearing is reported. Since nowadays the acoustic emission of gear systems is becoming a key objective, the identification of the structural contribution to the acoustic response can be useful both in designing low-emission mechanisms and for diagnostic purposes. Correlation methods based on vibration data and Selective Intensity approach are exploited for separating the acoustic contribution coming from the different components of the system. A comparison between the method and other noise source separation approaches is also discussed (Coherent Output Power and Partial Components Decomposition).