Noises
There are many types of noise that can affect recording. These are the main ones: quantization noise, rounding noise, aperture jitter, harmonic distortion, analog noise.
You can familiarize yourself with the descriptions of the four types of noise and the formulas to understand approximately how much distortion each type introduces into a digitized signal.
Do not take the term “noise” as a manifestation of the well-known “white noise”. Different types of noise are perceived differently, in this context the term “noise” should be understood rather as the loss of a part of the useful signal.
It is still possible to roughly calculate one type of noise separately, but the general noise level during digitizing is hardly. This is a very complex mathematical model with many assumptions. Let’s try to go from the opposite and analyze the dynamic range of the signal recorded in the ADC (analog-digital converter) and compare it with what is theoretically possible.
The noise level is generally calculated in relation to the quantization step (one bit) or the dynamic range of the audio signal. The dynamic range is measured in decibels, it can be calculated by the formula: DR = 20lg (2 N), where N is the quantization bit. It turns out that for 16 bits the possible dynamic range is about 96 dB and for 24 bits about 144 dB.
I will take the results of testing the ADC “Lynx Studio Hilo TB”, this is a studio ADC / DAC of the highest price category. It showed the following results.
WORKING HOURS 24 BITS, 44 KHZ
Dynamic range, dB (A) 119.3 Fine
And here are the results without amplification.
WORKING HOURS 24 BITS, 44 KHZ
Dynamic range, dB (A) 112.6 Fine
Looking ahead, I will say that the tested ADC uses Dithering, Noise Shaping, and Decimation technologies, allowing for expanded dynamic range and reduced noise level. I will tell you more about these technologies in the next paragraph.
Now let’s estimate: 24 bits equals 144 dB; this is the possible dynamic range. We subtract the actual dynamic range of 119 dB from 144 dB, the noise loss will be 25 dB at best and 32 dB at worst. Unfortunately, it was not tested at 16-bit, but in terms of the ratio, the results should be even worse, since reducing the bit depth inevitably leads to increased noise. It turns out that about 1/5 of the signal is simply lost due to noise.
The picture is far from rosy. And if you dig deeper and consider how the sound is mixed in the recording studio, it becomes awkward. As a general rule, finished work is mixed from samples where the indicated noises are already present, as the samples are recorded on a similar ADC. Effects are then added that at least lead to resampling and associated rounding errors.
