Is my water meter or prv causing whine, and how do I fix it?

Question

I'm getting really loud whine whenever I turn on a faucet at full blast. I've narrowed it down to one of the two pictured components but I can't tell which of them is causing it.

The whine doesn't start up right away but instead takes a few seconds to spin up (and increase in pitch and volume). The same goes for when we turn off the faucet; it takes about 10-15 seconds to finally die down. There is also a whole house water filter right after the PRV.

Which component is more likely to be whining given the above description, and is there anything I can do to fix it?

Update:

It was the prv. Finally got a plumber out to replace it (along with some other work) and the whine was eliminated

Answer 1

Normally PRV valves take a few seconds to get to the position that is needed to keep the pressure at the set point, I would suggest this is the source of the wine or squeal the water meter if you listen has a little shuttle that goes back and forth the more water that is used the faster it goes back and forth. A PRV has a diaphragm that is spring loaded that controls the actual valve, in some cases the wine or squeal is caused because how far the valve is opened and the fast water flowing through the chambers cause the wine, in other cases at the low flow side a similar thing can happen at a very low flow as far as noise. In the case of low flow it is the valve trying to close and open very slightly this is not normally as loud but the PRV is much more likely to be the cause.