What exactly does compression do?

[Swolock]

Another question from a newbie... my Yamaha CP4 has a compression button on it. I really don't understand what it does. Can someone please attempt to explain what it does and when to use it (or not to) to a not very technical person? Thanks

 

[delaware dave]

Compression is the process of lessening the dynamic range between the loudest and quietest parts of an audio signal. This is done by boosting the quieter signals and attenuating the louder signal.

So you are reducing the loudness range between the soft notes and the loud notes.

http://music.tutsplus.com/tutorials/the-beginners-guide-to-compression--audio-953

 

[Swolock]

Thanks.