You would be able to put multiple horn or bell sounds for a model, and then there would be a section in the paint scheme picker menu with a "horn / bell picker" kind of like the track type picker menu where there is a a track style button that opens a menu with all the track types. It could be basically the same menu, but where you pick the horn. The menu would contain every default horn / bell as well as custom ones, so you could still pick one of the default horns / bells. The same menu would be available on steam locomotives, just with whistles. This feature would allow for much more variety by being able to use different horns / bells on the same unit especially for packs that have many railroad paint schemes on one locomotive with each railroad using a different horn or bell.