If you have Win XP or 7 32 bit you can download our beta Splitcam (with sound supported) this version can play audio files and this time you can tell something in mic , also you can change your voice . The version not work on Windows 64 bithttp://splitcamera.com/SplitCam55beta.exe
After you installed this version , reboot your pc .
When you open program in right bottom corner you can see Audio button, there you can add files and work with mixer.
Also in Skype,Yahoo and etc you need go to preferences and choose in MIC (not your microphone) you need choose SplitCam Audio.