signal to noise (STN)
Signal to Noise (STN) is the ratio between the signal level and the level of the interfering signals. The interfering signal can be noise or hum, which can be caused by crosstalk, irradiation of mains voltages, of pulses, etc.
The signal-to-noise ratio, expressed in decibels( dB), applies equally to voice, audio and video and is a measure of the transmission quality of communications systems.
Analog audio has a signal-to-noise ratio of about 60 dB; for digital audio, the signal-to-noise ratio depends on the level of quantization and is about 100 dB at 16 bits. In communication systems, the error rate and transmission range depend directly on the signal-to-noise ratio.