To answer your second question, I hear such sounds on all types of TVs including flat screens, but it sounds different and is less noticeable than the sound made by older televisions. For whatever reason, I am more sensitive than the average person to these high frequency noises, though, so most people probably can’t hear the noise of a flat screen. Most people don’t hear sounds made by old TVs either, in my experience. My family thinks I’m crazy because I can tell when a TV is on from across the house from this noise alone, but they can’t hear it when they’re in the same room.