paper ID: 299 /p.1

On the use of double layer beamforming antenna for industrial applications Jean-Claude Pascala and Jing-Fang Lib a

Laboratoire d'Acoustique de l'Université du Maine (UMR CNRS 6613) and Ecole Nationale Supérieure d'Ingénieurs du Mans (ENSIM) Université du Maine, rue Aristote, 72000 Le Mans, France, [email protected] b

Visual VibroAcoustics, 51 rue d'Alger, 72000 Le Mans, France Email: [email protected]

Beamforming microphone antennas have now been widely used in the field of the automotive industry to locate sound sources on transport systems and to build acoustic models. The fields of application are the analysis of the pass-by noise of vehicles, the aero-acoustic noise identification and the source localization in cockpits. The analysis of the mechanical systems results in using more and more these antennas in near fields. In this article, a double layer microphone antenna is proposed and examined. Based on the numerical simulations, analysis is made in order to establish a source identification model using wave fronts of the sound pressure and the particle velocity, which are determined by finite difference between the two layers of microphones. The objective of this processing is to obtain a better localization and identification of the mechanisms of generation of the noise when the antenna is employed in near field (for example, ten centimetres from source). The other advantage of the double layer antenna is the possible attenuation of the back wave. This characteristic can particularly be useful for measurements in cockpit. Its interest is evaluated by simulation in a multi-sources environment.