Ike wrote:
For the past 3-4 years, we have heard an intermittent
humming/vibration sound in our house. The sound is loudest in the
master bedroom (of course) and eminates from the wall on my side of
the bed. The sound is loud enough to hear in most parts of the house.
I have gone to great lengths to find out what is causing this sound.

SNIP

Certain brands of toilet ballcock will create this kind of
hum/resonance sound.

To prove it, close the shut off valve to the toilet and see
if the noise stops. If so, either replace that ballcock or
get the mfr rebuild kit.

Jim