Music is distinguished by what is often called “dynamic” and which refers to the changes (more or less abrupt) of the “effort” with which certain notes or passages are interpreted.
Whether it is an instrument or the voice.

Any vocal performance that has been considered virtuous, in general terms, will have a dynamic that goes from very soft passages, almost whispered, to intense passages, with a high volume, singing at full voice.

At the time when vinyl existed as the option to listen to music, it was not felt (at least it went almost unnoticed) the fact of noticeable differences between the loudness or the volume of a song.

It was with the advent of digitization and the possibility of its variants (opting for different bitrates, sample rates, bitdepths, etc.) that this difference became very evident.

And with the appearance of mp3 and its distribution or exchange, at the same time that winamp and distribution lists arose, when it was inevitable and it was even started to look for solutions.

These first ones were based on the sound peaks and their results were very inefficient.

Returning to the mention of the mp3, situations such as masking (where information is removed) further marked the problem of differences in volume.

Then began to use the RMS that rather mediates the average power that the song had, more than the peaks.

Initially, it was enough to put a slower reaction level to the volume meter, to have a more general idea and less impacted by the volume peaks.

And so, the way of listening to music and considering what normalization was evolved.

Finally it appears to be somewhat closer to a mixture of a volume limiter and a compressor.

What is a volume limiter? It is a hardware (although lately there are also limiters in software version) that ensures that no peak exceeds a maximum limit.

A compressor, on the other hand, is a device or software that is used to “compact” the volume, preventing the parts with the lowest volume from being too low and at the same time preventing the high parts from exceeding a range that has been assigned. We would say that the compressor dampens the increases and decreases in volume.

To this we can add an equalization that differentiates the bands and treats them differently both in the limitation and in the compression. Each frequency band has a different treatment in the Mp4gain and that produces a very efficient result. It is NOT the only improvement offered by Mp4Gain, but this is described here. In other articles we will deal with other differences.

Mp4Gain is the best normalizer of 2020 and this is clear when using it.