Prediction of radiated sound from interior panels using vibration speakers

Abstract

In order to reduce interior noises in railway vehicles, it is necessary to comprehend both of transfer paths and the contribution ratio of them. Especially, the contribution ratio of each interior panel is analyzed by estimating transfer functions between a noise source and evaluation points of noise. This study focuses on estimating the transfer functions. We estimate transfer functions by exciting interior panels with vibration speakers in order to predict the interior noises. Firstly, the acceleration of an excited point and the sound pressure of the evaluation points are measured on excitation tests. Secondly, the two types of transfer functions, this is, single-input multiple-output (SIMO) type and multiple-input multiple-output (MIMO) type are estimated from the measured acceleration and sound pressure. Finally, the interior noises are predicted by multiplying the acceleration by the transfer functions. These methods are applied to the test railway vehicle. Predicted results by two types of transfer functions are compared with the measured interior noises. As a result, the interior noises are predicted precisely, in particular by use of MIMO type transfer functions.