Signal-to-noise ratio (frequently shortened SNR or else S/N) is an electrical engineering extent, also used in further fields (for example scientific measurement or else genetic cell signaling), distinct as the ratio of a signal power to the noise power mortifying the signal. A ratio superior than 1:1 specify more signal than sound.

In fewer technical conditions, signal-to-noise ratio contrasts the level of a preferred signal (for example music) to the level of backdrop sound. The higher the ratio, the fewer prominent the background noise is.