Usage of the 2.5D Boundary Element Method for the Detection of Moving Noise Sources

Abstract

The boundary element method in 2.5D allows for the usage of moving sources by a modification in the wave number frequency domain. The 2.5D boundary element method uses a Fourier transformation about time and the axis of movement of the object. The boundary element method is applied to the cross section. To use the method it has to be assumed that the cross section is constant along the direction of movement. An advantage of the method is that reflections in the sound path caused by the ground are taken into account. The inverse form of the method is used for the detection of noise sources on railway trains. Recordings made with a 64-channel microphone array at the high-speed railway line near Vienna will be investigated by this method. A big disadvantage is the fact that only eight positions along the track and eight positions in the cross section were measured. This leads to the fact that the wave number can only be estimated in as rough manner and that the IBEM has much more unknowns than measured position exist. The second point needs for a regularization. An advantage of the method is that the vibration at the surface is determined.