Maybe I'm wrong but I would say that you go across something (for example a field) where the "visibility" is good, I mean, you see the point/place you are heading for...but when you go through something (for example a forest) you don't see your "destination"...
To go across something is to cross it, to pass from one side to the other on an intersecting path. (The two intersecting paths resemble a cross.) We go across a street when we pass from one side of it to the other.
To go through something is to enter it and exit on the other side or end. We go through a tunnel when we enter at one end and exit at the other or when we go across it in an intersecting tunnel.
We we go across a forested area, we can say we go through it because we enter it and exit it.
We go across a bridge because we get onto it, walk over, and then get off it. We don't say we go through it because we don't enter (go into) and exit (come out of) it.
very clear, forero, thanks!
So, if I am talking about a voice which crosses a wall from a side to the other side (from a room to the next one) I should say "the voice through the wall", as the voice gets into and out the wall, shouldn't I?