What is the sound I'm hearing?

electronic hum. Electronic noise exists in all circuits and devices as a result of thermal noise, also referred to as Johnson Noise.

Johnson–Nyquist noise is the noise generated by the thermal agitation of the charge carriers (the electrons) inside an electrical conductor in equilibrium, which happens regardless of any applied voltage.

this is part of the reason that life in the developed nations is driving people crazy. this stuff has been going on now for over a hundred years in america; several generations. there is probably nowhere in usa that you can completely escape this background noise.

Good question, but I have no clue as to what the answer is.

I know what you are talking about. I can walk past a room in a hotel or an open apartment window on the street and can tell if the TV is on.

I guess it's just the sound of a TV's inner workings?

Yeah, same hear. Any CRT monitor turned on. It's from the high frequency vibrations emitting from the gun that fires the image onto the screen. Thank god for flat screens and flat panels!

I don't know what causes the sound, but I hear it too, when a t.v. or monitor is first turned on especially. Sometimes I can tell if a neighbor is watching t.v. Annoying, to say the least. Maybe it's the government beaming instructions into our heads? "Must vote Republican..." Or the ad agencies? "Must buy useless crap..." Or Hollywood? "Must watch stupid Adam Sandler movies..." Or your Mom? "Must clean room and do dishes and not have premarital sex with underage transvestite midgets..."

It's probably the horizonal sweep rate, if it's a high pitched frequency. The frequency is 15734.264 Hz for all NTSC (non PAL) sets.

my best guess is that it's the ringing in your own ears. other than that i don't know