Unfortunately, compression/limiting is far more difficult to repair than clipping (and this is difficult enough).
I've never found any tool designed especially for this, could you please give more detailed information
is this true? They compress the sound so that it can be made louder, and sound better to idiots?
I believe that compressed audio can be broadcast more efficently than uncompressed. I am not an engineer but I do remember reading an article a long time ago in AUDIO that said that.
In theory expansion with the exact contrary settings to the previous compression can reverse the previous compression. The problem is to find out the settings of the compression.
Well, why do they do this?
The available dynamics of FM broadcasting are surely not more than 45 dB (foot- and headroom and usable dynamics). There might be some classical recordings that exceed this dynamic range. So the decrease in sound quality (less dynamics) equals the increase (a higher signal-to-noise ratio).
I used to listen to FM with > 70dB S/N, it was not a Clear Channel station for sure.
Compressed music is a superior choice for a radio station because it means their signal can be heard further away from their broadcast tower. And because each additional mile of coverage means increasingly greater total square mileage (Pi*r^2), it is in the station's commercial interest to get that signal far.