As much as its nice to not hear everything on the map because of the top down perspective of the game its rare you actually hear any sounds from troops/ambiance unless you zoom very far in.
Personally it feels very out of place and makes the game feel so silent especially later on.
Especially with things such as speakers the range of their audio is so small it adds little to nothing.
Maybe make it so some of the sounds could be heard a couple blocks over, this can help emphasize CERC activity. If its felt that a farther range for sound effects is too much atleast make it so speakers can be heard more than a few meters away.