sound over voice thingy

I'm looking for the script/program or whatever it is that lets you play a sound from your computer over sound. I've done some searching on steamforums and google, but I can't seem to get the magic combination of keywords.

If you don't know what I'm talking about, in conflicts video, bahlk plays a "perfect" sound halfway through.

HLSS.

You take a song, you turn it into a .wav. You point the program to this .wav. You press del to start and stop the sound.

http://www.hlss.us/

A microphone is not needed to use this program though.

thanks a ton BI, I don't I would have found it.