Sound Source Identification for Tire-Pavement-Interactions Based on an Inverse Scheme

In this publication, we present sound source localization results at the rolling tire, mounted to a measurement trailer. A recently developed Inverse Scheme, combining microphone measurements and Finite Element simulations is applied at discrete frequencies to identify sound sources during the tire-pavement interaction. With this method, the actual boundary conditions of the measurement setup may be fully taken into account. In the first step, the Inverse Scheme’s performance is tested with stationary microphone measurements, where the trailer was excited with a loudspeaker. The source identification results showed that the Inverse Scheme is able to identify the dominant sound sources at the loudspeaker membrane well for frequencies f ≥ 300 Hz. In the second step, the measurement trailer was towed on Austrian highways, and tire/road noise was recorded with 37 microphones in a 3D array, including the ISO 11819-2 (CPX-Method) positions. With the Inverse Scheme, the dominant sound sources at the rolling tire could be identified in amplitude and phase. A comparison to results of Beamforming-based algorithms showed that the Inverse Scheme is able to identify additional weaker sound sources. Further, forward FE simulations with the identified sound sources prescribed to the tire were performed. Their results showed that with imposed sound sources identified via the Inverse Scheme, the simulated sound pressure matches the measured pressure at the microphone positions significantly better than with sound sources identified via beamforming-based methods. It has to be noted that all source identifications have been done to single-frequency tonal components with high signal-to-noise ratio.