The sound card is added by Computronics, a wonderful addon for OpenComputers. There are a few who actually know what it does. Even less people are able to use it. No one dares to understand how it works, or so I hope.
Anyway, it appeared a few years (?) ago, and is still mostly undocumented. There is a page in the in-game manual, which fails to explain how great the card is. Of course it does! It has a heap of different methods, which you can use to cast many crazy magics to make the sound card sound, and it's impossible to teach someone to do magic by reading a single page.
OK, I'm