What you are hearing is the 15,734 hertz oscillator frequency ringing in one of the coils or coming from the high voltage transformer. (Sounds like an RCA set, by the way). If it's bothering you to the point of distraction you may want to have it serviced. This is the time when an extended warranty may come in handy. You can either ask the technician to track it down to the actual part causing the noise, or the technician may, at his option, just replace the entire circuit board, which could be expensive.
If the TV in question is a traditional "tube", it is likely a sign that your tube is on its way out. Now's a great time and opportunity to move into HDTV!
What would cause a grinding noise after a tire is replaced and the brakes are not worn?
You can see why noise like vuvuzela noise, or other very loud noise are not cancelled by most or all headphones and what types of headphones would do it's best to cancel such noise here: electronics.howstuffworks .com/gadgets/audio-music/noise-canceling-headphone3.htm You can also learn how to try and rid yourself of such noise from your TV here: wikihow .com/Filter-the-Vuvuzela-Noise
A whistling noise indicates a vacuum leak.
cold engine
That is the most horrid dissonant noise ever. If anyone made that noise within 20 feet of me, I would make them eat their harmonica.
Brakes
Power Steering?
apples
loose or bad u joints.
what would cause a knockings noise in my boat 3560- 2004 transmission when in idle goes away when you give it gas
SEAT BELT
cv joints