Sound in the wall
A hiss in the wall is a reason to look, not a reason to cut.
Pressurized water can hiss, whistle, or sing behind paint. So can air in a line and some valves. Treat the sound as a clue and keep the wall closed until the search is planned.
Do not chase the sound with a knife.
A hole in the wrong bay wrecks finishes and can miss the line. Mark where it is loudest and when it happens.
Match the sound to a fixture.
If it starts when a tap opens, it may be flow. If it continues with everything off, it may be a leak or a passing valve. Write that down.
Call if the wall is also wet or warm.
Sound plus a soft spot, a stain, or a warm patch is an active-water problem. Call +1 (825) 782-8351 rather than waiting for a louder hiss.
Questions people ask
Is hissing always a leak?
No. Air, valves, and circulation lines make noise too. Wet material or a moving meter makes leak more likely.
Can acoustic listening find it without opening the wall?
It can narrow a pressurized line. It does not replace access when the evidence points to one bay.