Have had some interesting problems with propane
A couple hints I have not seen mentioned yet. A bit of dirt in the tank connection will do that. Now I don't have them refilled and swap them instead. And I have gotten some bad tanks. Check a lot around that connection.
That noise sure sounds like an internal noise with the regulator. I here echoing and that would be happening inside the unit.
Now one thing I do at times with noises is to get a dowel or rod like a couple feet long and then place it at various places and then listen to the end of the rod. With a direct connect like that if you are at the location of the noise you will hear it much louder and clearer. And that might tell you something.
I also have at times created a leak like not quite screwing the tank connector all the way on to make sure my soap is working and bubbling good. Some are much better than others.