Reduction of Interior Noise in an Automobile Passenger Compartment by Means of Active Structural Acoustic Control (ASAC)

Results of the latest research from the automotive industry corroborate the assumption that winds-hield vibrations occurring in normal driving mode are a crucial factor for interior noise in automobi-les. Due to the lack of passive damping methods that are compliant with the objectives of automoti-ve lightweight construction and the specific requirements of the system under consideration, only active methods can be used in order to appropriately address the low frequency noise. Thus the research presented here has been focused on the development of a structurally integrated and compliant ASAC-system for the active reduction of the sound pressure level (SPL) inside the car’s passenger cabin. In this work both adaptive feedforward and optimal state-feedback controllers have been designed and experimentally validated on a medium-class car. The use of highly effi-cient and global system identification methods based on structural sensors and laser-scanning vibrometer measurements allowed the definition of a global performance index for the controller design. In accordance with the numerical predictions on control performance the experimental re-sults showed global reductions in vibration level up to 7dB and reductions in SPL up to 15dB