Map height

[serthy]

I do not know how or if you can extend the skybox.
However, the stock maps use a texture called 'hint' (transparent greenish in tool iirc).
Iirc this texture tells the server, that upon this plane bullets doesn't need to be tracked anylonger.
Maybe this also prevents sounds been played. If its possible, you could hexedit this to another texture-type.
Obviously only after you checked the max-distances of the soundaliases, and if I'm even right with my theory...