Vibration Based Prediction of Noise in Passenger Car Gearbox Structures

In this paper, a method for predicting the contributions to noise radiated by a vehicle gearbox structure using measured vibration responses is presented. The gearbox structure is idealised as a set of flat plates. The radiation efficiency is calculated from the physical properties and edge constraints of each plate and the measured vibration response of the gearbox structure surfaces. These data were used in a simple acoustical power theory to determine 1/3-octave band sound pressure level under free field conditions for the whole and individual noise sources. The predicted individual noise sources are then used to pinpoint the exact problem area in the gearbox structure with a view to noise reduction.