Regulators operate by balancing a pressure diaphragm against a spring to control gas flow. They tend to be noisy. When the pressure stabilizes, the noise should stop.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk