I would say, if you act out of the normal, that is what can make rabbits nervous too. If you anticipate something bad happening rabbits can pick up that mood - imho a survival instinct, out grazing they do listen to birdsong, and react to other animals being alarmed. When I check on them on New Years Eve they are just happy someone is up at midnight to give them a treat, ignoring the fireworks.
My advice would be to just stay calm, ignore whatever is going on act normal, give a treat, etc.. I've never seen another animal that cares less about noise than rabbits. Which can cause problems, like when chopping wood or working with the chainsaw. I drooped a pan right beside my boy and he didn't even flinch.
Nothing that poses a danger to rabbits is loud. But a braking twig, some rustling in the bushes, someone coming around the corner unexpected (I start talking before they can see me) can send them running. They know way better what a danger is, and what not than many other animals - life would be difficult for them if they were afraid of everything, like many dogs. They are pretty pragmatic about new noises, if they don't recognise it as a sign of danger then it most likely isn't something to worry about too much.
Of course there might be individual excemptions, depending on character, how they grew up etc.
