Erich: i can't find any settings for that. There are lots of other settings for lights, for example: Weather, Time of Day, Coupling, Position in Train, Headlight Setting... (look in the techdocs file on MSTS CD1).
I have uploaded the Bc-t to ts-ef.com:
http://www.ts-ef.com/dsb.htm
I will upload the Bc-t here as well, but without the sounds.
I am making a big sound alias pack with updated .wag files for all the modern (UIC-Y and newer) DSB wagons, which will make a nice change from Micro$oft's own sounds.