Sound source analysis of moving rail vehicles with a microphone array

Projektname:	Analyzing the sound sources of passing-by rail vehicles with a microphone array
Contact:	Dipl.-Ing. Johannes Stier
Objective target:	Robust sound source localization

Current status:
The microphone array currently applied has a circular geometry consisting of two concentric circles. Altogether, up to 48 microphones are possible, from which 32 are used at the moment.

To localize and analyze the sound sources on moving trains, a self-developed time-domain delay-and-sum-beamforming algorithm is applied to microphone array measurements. The so called “emission-based delay-and-sum-beamforming for moving objects with known trajectory“ (see publication BeBeC2010) can also be applied to the localization of spatially stationary sources. The localization results in a set of acoustic maps of the passing train, one per frequency band, revealing the main sound sources:

Oktav band 500Hz

Oktav band 1 kHz

Because of the beamforming algorithm’s characteristics evaluating a microphone array pass-by measurement is very time-consuming and can take up to a few hours. Using state-of-the-art computational techniques for GPU and CPU parallelization of the algorithm’s implementation reduces the calculation time significantly (see publication BeBeC 2014).

By overlaying the acoustic map with a panorama picture of the passing train, it is easier to identify the train parts radiating sound. Especially for freight trains with arbitrary wagon types such a picture is very difficult to get. For this reason, a special approach was developed which is applied to video recordings of the moving train and generates a panorama picture of the train (see also publication BeBeC2012).

 (Video) (Standbild)
Duration: 07/2010 – today
Funding: self-funded

Publications:

BeBeC2014	Stier, J.; Hahn, Ch.; Zechel, G.; Beitelschmidt, M.: Computational optimization of a time-domain Beamforming algorithm using CPU and GPU, 5th Berlin Beamforming Conference, 2014
BeBeC2012	Stier, J.; Beitelschmidt, M.: Generating train side views from video sequences for microphone array pass-by measurements, 4th Berlin Beamforming Conference, 2012, Artikel
BeBeC2010	Zechel, G.; Zeibig, A.; Beitelschmidt, M.: Time-domain beamforming on moving objects with known trajectories. 3rd Berlin Beamforming Conference(BeBeC), Februar 2010. Artikel