How does music compression work?

Answer 1

Lets say the E's below represents a sound over a period of time with no compression.

EEEEEEEE

Depending on your compression settings, this sound can be affected differently. Let's say we want to catch the snap of the kick drum but don't want too much boominess you may want to use a fast attack and a longer decay. The results might look something like this.

Eeeeeeee

Notice the size of the letter representing volume changes. Now if you wanted to just do a quick compression to control part of the sound & then let the volume bounce back up, you would have a shorter decay which would look a bit like this:

EeeeeEEE

A good way of using these compression settings would be on guitar to keep it under control in a mix, while also creating a subtle rhythm with how that compression pushes the volume down & then releases it. You might be asking "why is the sound getting quieter when the compressor is on?" That's because it IS pushing the sound volume down but when you adjust the output volume gain, the sound has more punch.

Think of it like this:

If i have a sheet of paper and tried to throw it at you, it wouldnt have much effect, but if i crumple that paper more tightly (compress) and throw it at you it will have more impact.