Project content:

The harmful impact of noise has been the trigger for numerous legal regulations especially with regard to noise protection at workplaces. In order to improve workplace situations the limit values for noise exposure of employees are steadily tightened.

However, so far there were only conventional methods used for combating sound sources, e.g. disrupting the transmission path by means of vibration isolation or casing sound sources. But Smart Materials combined with modern control engineering made testing methods for active noise reduction possible during the last past years. Wölfel developed a technology allowing sound propagation of conventional machine enclosures as well as of sound insulating cabinets with high passive absorbers to be minimized by means of active absorbers.

Active absorbers are mechanical parts with one actor. The actor is controlled by electronics based on measured signals, provoking a vibration of the absorber in such a way as to superpose and thereby compensate vibrations of the sound source. Adequate control strategies allow for producing wide-band effect against sound propagation. Production plants represent the most important application area of active absorbers used for noise protection.