Gegenrauschen

Gegenrauschen is a German term used to describe the deliberate generation of counter-noise with the aim of reducing or canceling unwanted acoustic noise. The word combines Gegen- (“against”) and Rauschen (“noise”). In practice, Gegenrauschen is closely related to active noise control (ANC), a set of methods that create an anti-noise signal whose wavefront interferes destructively with the unwanted noise in a designated region, typically around a listener’s ears.

The typical Gegenrauschen system involves sensing ambient noise with microphones, computing an anti-noise waveform with a digital signal processor, and emitting it through loudspeakers or earphones. Adaptive filtering techniques, such as least-mean-squares or recursive-least-squares algorithms, are used to adjust the anti-noise to changing noise characteristics and reverberation. The goal is to achieve a quiet or more comfortable acoustic environment without increasing overall sound power.

Applications of Gegenrauschen include consumer headphones with active noise cancellation, aircraft and railway cabins, automotive interiors, and industrial enclosures. Its effectiveness is highest for steady, low-frequency noises and in relatively predictable sound fields. Performance can be limited by factors such as speaker and microphone placement, system latency, and the complexity of noise sources; open or highly reverberant spaces may reduce cancellation.

Terminology varies by language: Gegenrauschen is primarily used in German-language texts and discussions, while English-language literature typically uses “anti-noise” or “active noise cancellation.” The concept remains a central topic in acoustics and signal processing as a practical approach to noise control.