Experimental Study of Low-Mid Frequency Interior Noise of an SUV

Abstract

The reduction of wind noise of vehicle is important, mostly in the premium vehicle segment, in which the occupants are susceptible to the background noise inside the car. The elevated wind noise levels lead to discomfort and fatigue of the occupants in the car. It is hence a primary task that any windnoise concerns are analysed and resolved in the initial stages. A 3D spherical beamforming array is a effective tool for localising sound sources inside the vehicle. When performing wind noise measurements in the tunnel, it is important to acquire as much information as possible efficiently, since the facility time is usually costly. With the limited measurement time available, the spherical beamforming tool allows the localisation of the important acoustic sources. Thus, different configurations with geometry modifications can be tested to assisit the test engineers to the optimum configurations and improve the efficiency of measurements. The investigation involves characterisation of sound sources inside the vehicle caused by structural excitation due to turbulent flow forces acting on the car body. The noise transfer function measurements using the Laser Doppler Vibrometer (LDV) helps us to determine the resonance frequencies of the structure excited by the sound source. This report documents the integrated approach for localising airborne and structure borne noise sources inside the vehicle with acoustic beamforming and LDV techniques to pinpoint and measure sound sources distribution inside the car. The results validate the feasibility of the integrated approach using beamforming and LDV technology, offer new insight into the distribution of interior noise sources, and provide valuable input for improved product design for quieter and comfortable cabin noise.