How to increase the volume of the voice on the recording?

Question

Audio

There is a recording on which the voice is very quiet. What are the best ways to enhance/improve the sound of the voice? It is clear that we will not have a magic button, but at least push in the right direction.

Answer 1

In general, you will need the equalizer, gate, and compressor plugins.
There is no point in fooling around, because amplifying a digitized signal always entails amplifying the noise. And if the voice is very quiet, the result will be very noisy. So the scheme is as follows:
1. Raise the overall volume of the recording
2. Lower those frequencies in the equalizer that do not transmit the sound of the voice. This is up to about 80 Hz and from 10,000. Specific values ​​​​depend on the character of the voice and on the noise. Be careful with frequencies above 1000 Hz, because. they contain information from which we isolate consonants.
2a (Optional). you can raise the first few harmonics of the fundamental frequency of the voice. That is, if a person is mumbling and most of the signal power of his voice is in the area, say, 250 Hz, then you can play around with peaks of 250 * n Hz, where n is an integer. Sometimes it makes speech easier to understand. Modern equalizers often have frequency visualization, so finding peaks is as simple as looking at the screen.
3. Using the gate, remove the noise between speech sounds if this noise is noticeably quieter than the speech itself. The gate passes signals that are louder than a certain threshold. Advanced gate options have flexible settings that allow you to "jump ahead" and skip a quiet signal that will soon become loud. So you can not lose the quiet beginning of words, for example. Also, advanced gates can only look at the selected frequency range, and this _really_ makes noise reduction easier.
4. Compressor (optional) - dynamic processing. If, after the above processing, the signal jumps too loudly, you can comb it with a compressor by setting the compression to ~ 4 to 1. You can also play with other compression parameters, for example, with the response speed. It can also improve articulation.
Everything you need is out of the box in Reaper. The first 30 days are free.
Points 2 and 3 together, in principle, can be replaced by dynamic equalization. In Reaper, this is the ReaFIR plugin in Substract mode. First, let him listen to a few seconds of noise from your recording, he will build a noise profile and subtract it from the original signal. It works well if there is little noise at the frequencies that the voice occupies.
But there is a simpler option that can work:
There is such a wonderful product - Isotope RX - a set of plug-ins for signal recovery. A bunch of dodgy math that works wonders. The interface is elementary, you don't need to know the theory.
1. Download trial version of RX
2. Download Reaper.
3. In Reaper, throw your record and process it with RX plugins.
4 ...
5. Profit!

Answer 2

Install SoundForge there, you can greatly increase the volume of the entire recording, and then, if there is background noise, clear it.

Answer 3

You can do it in Audacity too. Also, first amplify, and then remove the noise.

Answer 4

By the way, it is not necessary to tinker with the equalizer manually - many editors have presets for voice processing.