I’ve been wondering… Is it possible to have a python script that applies a low-pass filter on a specific sound file in real-time while in the game engine? It would create a nice effect, say you pass through a tunnel or something, and the low-pass filter is applied.
sure you could use supercollider as your audio engine , and use pyosc for controlling supercollider’s audio server
Cool! Thanks for the responses! 
Another example here
https://blenderartists.org/forum/showthread.php?235329-Blender-Audio-System-(Aud)-example-(3d-and-2d