I've searched this forum and others but can't seem to find anyone with the same sounding noise. The house is 3 years old and we just started hearing a strange plumbing noise. This happens EVERY time any water is turned off anywhere in the house and sounds (pardon the example) like someone is trying to hold in a fart but failed and it slowly squeaked out. The sound is located between the 1/2 bath and master bathroom wall somewhere. I've tried to isolate it by shutting off each valve with no luck. I've also checked the pressure and I'm getting 82 psi at the outside faucet. After digging 4ft past the street cut off valve, I don't see a PRV.
Thank you for your time and any ideas would be greatly appreciated.
- Jeff

You need to install a PRV to get the pressure down to 45-55 PSI.

Your fixtures will break prematurely if you don't.

2nd, you need to completely drain and refill the water system. Air chambers, verticle capped pipes going nowhere need to be refilled with air so they act like shock absorbers again.

It really does sound like too much pressure and the air chambers are not doing it's job.

Securing pipes and loose washers tend to cause noises.

But, before we can take it further, you need to have both problems addressed.

I agree that the pressure needs to come down and that will be a top priority. I've drained and refilled the system again and the noise is the same. It seems to be loudest from the wall behind the 1/2 bath sink... if that helps any.

Until the pressure is down, I doubt we can go further.

Although, the solutions generally would fall under:
1. Secure pipes
2. Check stops, washers, shutoffs for loose washers.
3. Add water hammer arresters

Slamming the water off is usually an arrestor/pipe securing problem. (commercial versions can be added under a lavoratory sink in any direction)

Noise changing with flow is typically a seal/washer problem.

Lowering the pressure can cure both.