Archives of Acoustics, 39, 3, pp. 385-394, 2014
10.2478/aoa-2014-0042

Acoustical Analysis of Enclosure as Initial Approach to Vehicle Induced Noise Analysis Comparatevely Using STFT and Wavelets

Andrzej BŁAŻEJEWSKI
Koszalin University of Technology
Poland

Piotr KOZIOŁ
Koszalin University of Technology
Poland

Maciej ŁUCZAK
Koszalin University of Technology
Poland

It is assumed in the paper that the signals in the enclosure in a transient period are similar to a noise induced by vehicles, tracks, cars, etc. passing by. The components of such signals usually points out specific dynamic processes running during the observation or measurements. In order to choose the best method of analysis of these phenomena, an acoustic field in a closed space with a sound source inside is created. Acoustic modes of this space influence the sound field. Analytically, the modal analyses describe the above mentioned phenomena. The experimental measurements were conducted in the room that might comprise the closed space with known boundary conditions and the sound source Brüel & Kjær Omni-directional type 4292 inside. To record sound signals before the field’s steady state was reached, the microphone type 4349 and the 4-channel frontend 3590 had been used. The obtained signals have been analysed by using two approaches, i.e. Fourier and the wavelet analysis, with the emphasis on their efficiency and the capability to recognise important details of the signal. The results obtained for the enclosure might lead to the formulation of a methodology for an extended investigation of a rail track or vehicles dynamics.
Keywords: modal analysis, short-time Fourier transform, wavelet transform, acoustic signal processing.
Full Text: PDF
Copyright © Polish Academy of Sciences & Institute of Fundamental Technological Research (IPPT PAN).

References

Blazejewski A. (2013), Modal analysis application in passive sound level control inside bounded space in steady state, Dynamical Systems-Application, 12th Conference of dynamical systems theory and applications, 409-421.

Koziol P. (2010), Wavelet approach for the vibratory analysis of beam-soil structures: Vibrations of dynamically loaded systems, VDM Verlag Dr. Müller.

Koziol P., Mares C. (2010), Wavelet approach for vibration analysis of fast moving load on a viscoelastic medium, Shock and Vibration, 17 (4-5), 461-472.

Koziol P., Mares C., Esat I. (2008), Wavelet approach to vibratory analysis of surface due to a load moving in the layer, International Journal of Solids and Structures, 45, 2140-2159.

Mallat S. (1998), A wavelet tour of signal processing, Academic Press Inc. Ltd, London.

Meissner, M. (2008), Influence of wall absorption on low-frequency dependence of reverberation time in room of irregular shape, Applied Acoustics, 69, 583–590.

Morse, P.M., Bolt, R.H. (1994), Sound waves in rooms, Reviews of Modern Physics, 16, 69–150.

Morse, P.M., Ingard, K.U. (1968), Theoretical acoustics, Mc Graw-Hill.




DOI: 10.2478/aoa-2014-0042