When a demigod is doing something (say attacking a tower) if you zoom the camera in on the action which only allows part of the DG to be seen (say only the weapon that is swung) then there are no action sounds (you don't hear combat).
It is not tuned down to a lower volume, but completely off. In fact in my situation there was quite a battle going on, but instead all I could hear was the music and the tower firing.
