Mute sound from given aplication

mute sound per application:
  int soundLevel = 0;
  muteSound(processId, 0); // mute all sounds
  wait...
  muteSound(processId, 100); // let it flow again

I believe this is a tricky thing to implement, per application sound
mute. I found IndieVolume program which claims to have per-application
audio mute.

But I need to use Delphi and embed it to my program. Any hints available
where to look for necessary api calls?

System: WinXP/Win2000