What is Signal to noise ratio (S/N)?
It compares a level of signal power to a level of noise power. It is the measurement used to describe how much the required sound is already in an audio recording as opposed to an unwanted sound or noise. When there are higher numbers it generally means a better specification, since there is more useful information that is the signal then there is unwanted data that is the noise. Defined as the ratio as the power(P) of a signal to the power(P) of the background noise. For example, you and your friend are talking to each other and there is a big crowd around you making a lot of disturbing noise. Your voices are the signal and the crowd around you is the noise so that you can hear each other, you try to make your voice louder. If the number is large more desired signals stand out in comparison to the noise, which means that the transmission is clear and the technical quality is better. And if the number is negative that means the noise is stronger than the desired signal due to which a phone conversation can be too garbled to understand.