When you travelling with El-Al to or from Israel, you see a lot of women - certainly also religious ones - shaking rather quickly, heavily (from my point of view),... their crying babies, of course to stop them (the babies) ennoying themselves (the parents) but certainly - I'm very sure - also to protect the other travellers. I was always asking myself if it was ok or not, because sometimes you read in papers that nannies, everywhere in the world, were brought to justice because their shaking was provoking the death of babies, entrusted to them. My opinion is: try to stop that, by soft moving from one side to the other, saying (singing) something softly (the baby knows your voice) and if it's not helping at all... don't care about it: the fellow traveller(s) have(s) to except it: some babies are nudnikim and everbody... has in his own family such a nudnik or maby more... amen!