Custom map sound problem in GMod

So I’ve downloaded this map called eawan_1, it’s supposedly a horror map for HL2 (you can read about it in the valve games and mods) but I want to play it in multiplayer via GMod. The author of the map said it worked just fine, so I started it in singleplayer GMod to test it out. Nice, everything is in order. Here’s the problem, though. When I start it in Multiplayer, the sounds that emit from the map completely vanish. No custom sounds whatsoever. Is there a fix to this? Any help would be appreciated.

I’m suspecting that some variables impact the audibility of the map sounds in multiplayer. I’ve searched for the variable which causes that, but I couldn’t find it, sorry :confused:

Bump. I need help on this.