automatic noise reduction (ANR)

Noise is extremely annoying in many techniques. In audio technology and acoustics, image processing and video editing, as well as in all radio technologies. There are therefore various techniques for noise reduction and noise suppression such as automatic noise reduction( ANR) or dynamic noise reduction( DNR). All of these techniques are concerned with improving playback quality and increasing the signal-to-noise ratio( SNR).

Automatic noise reduction (ANR) techniques can be those that reduce noise in photos or videos, reduce tape noise from magnetic tapes, or improve audio quality. Classical noise reduction techniques reduce the bandwidth by filters and thus the spectral noise density. Others increase the signal level of the frequency components most affected by the noise and later reduce it again in proportion to the level increase. Others work with companders and level compression.

In acoustic systems, there is a technique in which automatic noise reduction is realized by reducing the Q. This is done by a negative output resistor with which the coil resistance of the headphones is eliminated. And another technique, Active Noise Cancelling( ANC), works with interference techniques and compensates for noise interference by using noise signals in phase opposition.