@pitermach @tomecki I think you can use an app called easy effects for this. It even has some usefull built-in effects and is really easy to work with. It's an accessible GTK4 based app and does not require using the terminal directly.
@pvagner @pitermach Some time ago I tried to use it, but I had big problems. Now it worked. The problem I have at the moment is the lack of a good noise reduction. There is Speech Processor, but even with the reduction set to -1db it sounds bad. There is also a separate effect Noise Reduction, but instead of controls it only says "unavailable". Maybe it is not available on Arm?