MP3
From GDWiki
MPEG-1 Audio Layer 3, or MP3, was the first widely popular method for massive compression of audio files; raw audio data is often compressed to less than one tenth of its original size, when encoded as an MP3. MPEG is the Moving Picture Experts Group under whose guidance the MP3 audio format was created. MP3 is encoded by mainly discarding data that the human ear does not hear, somewhat like the way a JPEG discards the data the human eye cannot see.
Unfortunately, in order to use MP3 compression in your game you will have to obtain a license for its use. For this reason, you may wish to look into the (superior quality wise) OGG file format instead, as the OGG format is free to use, and unencumbered by patents. The Vorbis part of OGG is the sound compression codec.
