M.S.
I think that the baby would be used to it, since that will be her/his normal enviroment.
Do you children have rest time? I usually have a quiet/rest time, same day everyday and we always go over the rules that it is time to lay down, no playing or talking while the movie is on, most of the little ones fall asleep. It takes awhile to get them to get on a routine.
If they are older children I would try to just let them play in thier rooms or be in a area away from the sleeping baby. All you can do is keep reminding them that the baby is sleeping, let's try to be quiet.
Kids will be kids, lol.