Just a quick question about audio for games (not sure if this is the right place to post it though)

I'm trying to find out how much memory is usually allotted for audio on a PC game.

I recently purchased "The Game Audio Tutorial" which is perfect for sounds and implementing them on UDK but i'm stuck at an in-pass that i don't know how much memory is usually used on audio for games. The book says it the lowest figure for audio for games on something like a PC game is 15MB to 25 MB. Could anybody elaborate on this?

Thanks