heh, first of all don’t call it a shader. the word shader doesn’t mean a script that modifies how the engine does something- there’s no shading involved in sound. you wouldn’t call a baby zebra a kitten, would you? same thing.
Now that the technicalities are out of the way- I believe what you’re referring to is called EAX (or maybe that’s just the name of one product that does this)- modifying sound based on the environment. AFAIK, blender can’t do this yet.
-The best you could do is working with the volume, for example when a bomb goes off near the player, all sound’s volumes are reduced by X percent for Y time, or when the sound is in another room the volume drops X percent. you couldn’t cut just the low-end or whatnot though. also, you’d have to figure out how to define which room things are in, etc.