I feel sorry for house dogs and cats, they must be going crazy listening to all the irritating electronic noises that most people don't notice.

Similarly: birds and old CRTs and fluorescent lights (they are much more sensitive to the flickering than we are)

i've noticed more and more cheap USB wall-wart chargers. I can hear them pulsing, it's sort of interesting, but super frustrating when trying to go to sleep (I end up just unplugging.. for which you can hear it scream as it drains)

I used to love the idea of a device without fans or spinning hard drive. But the last two "silent" tablets I've had randomly made very faint, but annoying, high pitch squeaking. Vibrating capacitors, I think. So ironically, I was better off with at least a low speed fan to provide white noise to cover up this faint electronic noise.

Exactly, it doesn't even need to have a picture on the screen.