A wise man said to read tutorials it will help, also I'm not sure but if I'm guessing all you did was rename the file and place .MP3 at the end of it, of course it won't work like that.
Audacity is your free sound editor, and can compress sounds to. Just set it to 96000 Hz , once imported to the map change the sound variable pitch to .46 around and it will sound the same thing although the quality will be slightly lowered.