Spiker, we had some friends over to watch a movie on Saturday so I rented the Two Towers again since they haven't seen it and my curiosity over this scene was getting the best of me. Yes the wall explosion is felt more than heard, but I believe this is more the way it should sound. I have had the unfortunate experience of being present during an explosion, it is felt more than heard. You can feel it hit your chest, car alarms hundreds of yard away go off, and yet you don't hear much bass but a deep low rumble. So I think Two Towers actually did a fine job with this scene.