Why does a gas regulator make a whistle noise when being used?
Answers:
it's the gas moving over the diaphram - thre's no way to fix it. You'd have to replace it. It isn't failing though, so it's not hurting anything.
Other answers:
It ain't broke, don't fix it
It ain't broke, don't fix it
The gas passing through the orifice makes the noise. Sometimes turning the pressure screw 1 turn higher or lower may stop it.