Recent advances in active noise and vibration control

Noise is a serious form of environmental pollution believed to affect the lives of some 100 million European citizens. The cost of the associated damage is estimated at more than ten billion euros per year. Noise leads to serious health problems, limits the capability to learn, and effects the occupants' comfort and performance in buildings, in vehicles or at work. For instance, the automotive industry is more and more facing the problem of reducing the weight of the vehicle but guaranteeing an equivalent level of comfort in terms of noise, vibration, and harshness (NVH). Improvement of vehicle noise and vibration without affecting other performances is proving to be extremely difficult if not impossible with state-of-the-art technology. Thus, active or smart concepts are being increasingly considered for the NVH optimization of vehicles besides advanced passive material systems. Within the LOEWE-Center AdRIA (Adaptronics - Research, Innovation, Application), a large interdisciplinary research project funded by the German federal state Hessen, and at the Fraunhofer LBF advanced noise and vibration abatement concepts were being developed and demonstrated. Among others, NVH abatement in vehicles and noise abatement in buildings is being considered. As underlying principle for noise reduction concepts, active structural acoustic control (ASAC) is primarily being considered for controlling the structural vibration of the sound radiating structure or by controlling the structure borne sound path. This paper will present an overview of the most recent concepts and results of the LOEWE-Center AdRIA such as active vibration control at engine mounts and smart windows. Examples presented will include active mounts, inertial mass actuators, shunt technologies with piezoelectric ceramics and smart Helmholtz resonators.