I have an Emerson 42-inch LCD TV that has developed a static sound when it is on.
This has gotten progressively worse.
It use to be that the static was only heard when the TV was turned on,
and then when we'd put it on a program, it would go away.
Now, it remains regardless of whether we watch through Roku or DVD or a video game.
It has gotten louder to the point that it is intolerable.
The sounds does not go away by unplugging things.
It is there any time the TV is on.
Also, it sometimes makes kind of a ping noise when turned on with the button,
and it sort of makes a whining noise when turned off.
The TV is probably 8 or so years old, so I'm guessing it might just be time to replace it,
but if there's any hope of a simple fix, it might be worth a try.