Voice Range Module?

I was searching gmod.org for a way to make Voice chat ranged, but make it so that the voice would not be carried through walls… And then I ran across this;
http://www.garrysmod.org/downloads/?a=view&id=67459

Unfortunately the description is crap and doesn’t really explain/help me with anything. So, I was wondering if anyone knows what this does? (Mainly, where do I put the .cpp file?) The gm_voice.dll obviously goes in lua/includes/modules but I don’t know where the .cpp file goes… Plus, I don’t even know if this will work or not. Any ideas?

Its built into garrysmod now, kinda. You will need to write a script that uses traces to check for walls

The cpp is the source file, here’s what tobba is talking about: