A device for active noise reduction has a chamber, which is arranged
laterally in relation to a gas flow, and a chamber opening constructed in
one wall of the chamber. In the area of the chamber opening, a deflection
device is adjustably arranged. The deflection device, in a first
position, at least partially directs the gas flow running by the chamber
opening into the chamber, in order to compress air there, and, in a
second position, directs the gas from the chamber to the gas flow, in
order to release the gas inside the chamber. The resulting alternating
pressure inside the chamber is radiated through the chamber opening as
sound and overlays the disturbing sound.