The tank cars will go completely silent when moving at speed on the Aachen -Köln route, sounds only seem to come from the front loco and the rear car resulting in the other cars being completely silent
I don't think the problem has anything to do with the wagons, but it has been identified in this way. I suppose it is a much more general problem, as I have noticed a similar effect near railway crossings on American routes (SPG, SFJ). The bells at these crossings produce a deafening noise, but when you are on a walk and you are close by, you can turn in a certain direction where this noise is suddenly inaudible. It is only a few angular degrees.
