Little Question about MuseScore

I'm deeply curious, is there any way to replace the default sounds for the instruments used by MuseScore? I have a set of much more realistic sounds I'd like to replace. I searched the MuseScore program files directory but was unable to find the sounds. I also want to know what format they are in. I figured if I downloaded the source of the program, I would be able to compile it and that surely the sounds would be visible in the source, but they weren't. What am I doing wrong?