[Cohiba]

I am getting a hi-pitch ringing tone that goes in and out behind my bedroom wall (almost like a vegas slot machine -- a fading ding ding ding).

Strange thing too is at that it will literally stop for 3-4 days and then come back on all night, going in an out - a fading ding ding ding.

While it was making the noise:

-- I shut off main electricty panel to house, still ringing
-- shut of main water and opened a faucet to drain thinking air, still ringing
-- turned on main sprinkler system, still ringing; as there is a drip system on opposite wall in flower planter outside and i do hear loud shut off valve noise behind wall when they switch to other water areas, I guess

Any other thoughts/suggestions?

 

[AllanJ]

What is on the other side of the wall? Do you live in a multi-family building or apartment house where the other side of the wall is someone else's home?

 

[mustangmike3789]

is it possible that someone doing lawn maintenance lost a watch outside of your room.

 

[Cohiba]

nothing on other side, small flower bed with sprinkler drip...but on the outside

 

[Pistol Pete]

Could be aluminum siding or gutters or something similar that's expanding/contracting as the temperature changes. Or it could be heating pipes or ducts, also reacting to temperature change.

Or maybe some mice have opened a casino inside your wall, although this seems unlikely.

 

[josall]

Is there a toilet close, could be the flush valve is leaking or the tank flapper is leaking causing the valve to run.