[Hardware]Signal-to-noise ratio or SNR in audio, what is it and why is it important?

[WilkerCSBD]

When choosing any audio product that emits sound (that is, for example the sound card integrated into your motherboard), one of the parameters that manufacturers always specify (or at least must do) is the signal-to-signal ratio. noise, sometimes simply called SNR for short. However, it is expressed in a value that without having a reference we cannot know if it is good or bad, so in this article we are going to tell you what the signal-to-noise ratio is in audio devices, what is measured and what is it for.

Actually, when we talk about audio products, there are many parameters that manufacturers inform us about, but unless you are clear about what each of them is, they will be of little use except to buy the values of one product with those of another, and even so Maybe you don't know if a higher SNR is better for a certain product or maybe the product with a lower signal-to-noise ratio is the most appropriate, so let's get into the matter to determine it properly.

What is signal-to-noise ratio or SNR?
The signal-to-noise ratio, S / R or SNR (Signal to Noise Ratio) is defined as the ratio between the output power of the transmitted signal and the power of the noise that corrupts it (therefore we only speak of devices that emit sound and never of devices that pick up it). This margin is measured, like almost everything related to audio, in decibels.

Often times, many manufacturers use the term dynamic range as a synonym for SNR, but you must be careful because some use it as a marketing strategy to make it appear that it is the SNR when in reality the dynamic range serves to indicate the distance between the level of output peak and background noise. That in the technical specifications of a device appears the signal-to-noise ratio indicated in decibels, therefore, it does not mean anything if it is not accompanied by the reference points used, as well as the weightings.

To correctly indicate the dynamic range, the decibel measurement must be accompanied by the weighting curve and the reference level used to measure it. For example, imagine a device that has these characteristics: 60 dB, CIR 468-3 (ref. 1 KHz, 320 nWb / m − 1). In this case:

CIR 468-3 is the weighting curve.
1 KHz is the frequency used as a reference.
320 nWb / m − 1 is the magnetic level at which the reference level has been recorded.
Obviously, if you want to buy equipment in terms of its frequency response, they must have measured the signal-to-noise ratio using the same weighting curve and reference level, something that is fortunately the most common in the industry, so SNR levels are normally comparative.

Noise factor
When we talk about noise in an audio device, we are not referring to background noise, since this can obviously change depending on the circumstances, location, or if there is a man honking the horn of his vehicle at a traffic light near your window. No, noise when we talk about audio refers to the magnitude of noise generated by the electronic device itself, such as the noise that an amplifier puts into the signal.

Integrated sound card amplifier
This magnitude of noise can be expressed by the so-called noise factor (F), which is the result of dividing the signal-to-noise ratio at the input (S / R) by the signal-to-noise ratio at the output (S / R ) salt, when the signal and noise values are expressed in simple values. The formula would therefore be expressed as follows:

Noise factor formula
However and much to our regret, the values of the signal-to-noise ratio are expressed in decibels and therefore we speak of a logarithmic formula. Since the noise factor must also be expressed in decibels as the audio magnitude that it is, then the formula would be as follows:

Logarithmic noise factor in decibels
The noise factor is a very important magnitude in audio transmission systems since while external noise can never be completely eliminated, reducing the noise generated by the audio equipment themselves depends on the care of its design, so that said of otherwise, the lower the noise factor, the more the manufacturer has pampered its design, delivering better quality.

Is a higher or lower SNR better?

Summarizing the above so that it is clearer, the signal-to-noise ratio is what separates the emitted power of a device with the noise that affects it, and therefore the greater this difference, the better. Therefore, when choosing a sound card, amplifier or other audio emitting device, when you look at its technical specifications you should know that the one with the highest SNR will provide a greater signal power, which will less tend to be affected by the noise of the Precisely, this is a parameter that although most manufacturers know they do not publish it, "hiding their shame" to put it in some way if their product is not good. For this reason, it is normal that only manufacturers of professional audio products publish this value, since if their product is indeed good and of quality, they will have nothing to hide. In any case, don't worry either because none of the audio products you have your eye on does not specify this factor, since for an ordinary user it is not going to make a difference either.