So, I've converted one of my favorite songs from a mp3 file to a wav file, but there's no sound coming through whenever a new game starts up. What's happening?

pretty sure you need to type some chat command stuff for it to work, don't remember any details though

The sound has to be less than 5 seconds and of a small file size

Kiai sound tutorial

Pretty sure he's talking about a Music item, not a Kiai.
Try turning up your music volume in the options. I believe I had the same problem a while ago.