Abstract
KEYWORDS – Array measurement, Pass-by noise, Quantitative, Patch measurement, 3D sound source localization.
ABSTRACT –
European new standard regulation (UN ECE R51-03) will command to car manufacturer to decrease pass by noise levels of their cars. In that context, Vibratec, Renault and MicrodB, part of a 10 companies research project, have decided to launch the ECOBEX project [1]. The global objective is to propose breakthrough solutions in order to design acoustic treatment of the engine. The experimental characterization of acoustical sources generated by the engine is a preliminary requirement to achieve the project objective. The work leaded by MicrodB aims at getting accurate localization and quantification of the sources on chassis dyno bench, and engine test bench. The proposed method called “patch measurement” is based on the sequential measurement of acoustic field around the engine moving the array of microphones. The first technical challenge is to obtain a fully synchronized signal for each microphone from this patch measurement. Then, the estimation of the microphones position relatively to the mesh of the tested object represents the second difficulty. The third challenge is to use the proper propagation acoustical model that are mandatory for quantitative source estimation. Finally, the last task is to correctly compute the radiated intensity on the 3D mesh. This paper will describe at first the methodology used for all these steps and it will present the results obtained during the ECOBEX project.