Measurements of acoustic response of car interion for structural excitations

The transition from internal combustion to electric propulsion in cars presents component designers with new challenges in terms of noise reduction. Until now, components such as the suspension, its knocks were masked by the combustion engine or exhaust system. The absence of such significant sources, means that hitherto inaudible components are starting to become a nuisance. In order to reduce their noise, a number of optimisation solutions, both active and passive, are used. In order to do so, relevant measurements and data analysis must be carried out. This paper aims to present the acoustic characteristics of the interiors of two cars excited structurally in the vicinity of the front shock absorber mounting and by the operation of another component, the windscreen wipers on dry and wet windscreens. Measurements were made using 3D intensity probes based on acoustic particle velocity sensors. The results, in the form of both acoustic particle velocity and sound pressure characteristics and spectrograms, are presented comparatively for two types of car.