However, silencer baffles can attain a satisfactory effect at low frequencies only with large quantities of absorption material. Active silencers, that work after the noise decrease principle through reverse sound are capable to particularly reduce also low-frequency sonic emissions efficiently. Such ANC Active Noise Control systems save sonic absorption material, space occupied and weight and reduce environmental strain, energy and overheads.

Together with a team of engineers of the IBS Ingenieurbüro für Schall- und Schwingungstechnik GmbH, the company WENDT SIT GmbH tested successfully an active silencer prototype under operational conditions. The noise emission at the exhaust chimney of a paper mill which was characterised through tonal components could clearly be lowered. Opposite a conventional silencer baffle, the use of the ANC silencer reduced the passive absorption material by 62.5 Vol % and the overall length by 25 %. The practice test optimised and prepared the ANC systems for a wide-ranged industrial use.