The influence of the tyre air cavity on the rolling noise

Road traffic is the main source of environmental noise. While combustion noise has been reduced over the years, it appears to be difficult to reduce rolling noise. Even for electrical vehicles at moderate speeds rolling noise is a main contributor to the exterior noise. The main cause of rolling noise is the excitation of vibrations on the tyre structure by contact forces due to varying road roughness and/or tyre profile. However, we know that when rolling over obstacles like rails or bridge joints, the cavity noise due to the excitation of tyre cavity modes is clearly audible. Therefore, one can assume that cavity modes also contribute to tyre/road noise on rough roads. This paper makes the attempt to demonstrate the contribution of cavity noise as function of road roughness and tyre profile. The Chalmers tyre/road interaction model is used for the simulations. A modified radiation model allows for calculating the contribution of each individual tyre mode to the radiated sound. In this way the contribution of the cavity modes can be determined. Results indicate that at least for rough road surfaces the contribution of the cavity modes is of importance for the exterior sound.