dynamic noise reduction (Audio) (DNR)

Dynamic noise reduction (DNR) is a process used in audio recording, transmission and recording.

With dynamic noise reduction, the high frequencies are boosted before transmission or recording - they then have a disproportionately higher amplitude - and then lowered back to the correct level during playback. This process is also used in FM broadcasting and is known as the Emphasis technique with Pre-Emphasis and De-Emphasis.

The purpose of this procedure is that the noise has high frequencies. But if the high tones have a higher level, then the signal-to-noise ratio is correspondingly higher.System of noise reduction in audio. DNR raises the strength of the highest frequency when recording, for example, on magnetic tape, and restores the normal strength during playback.