Buzzing When tv is on there is a buzzing noise which changes tone when picture changes./

The noise is caused by dust on one of the toroidal transformers(usually a round looking thing with wire wound around it). Go to the back of your television and try and pinpoint were the sound is coming from. Turn your television off and blow it out with compressed air if it is close to air vents in the television. If you cant see it you might have to open your television back panel.

Go to the rear of the set and listen to where the noise is coming from, squeeze the top corners and see if the sound get muffled, take the back off the set and line the edges of the back cover with some insulation foam that is used around doors, it should quiet it down some, the panels buzz in most 42 inch and above plasmas and it's normal, you can also put RTV silicon around the transformers and large capacitors, they have a tendency to produce a loud humming or buzzing sound also

1. The buzz is related to the intensity of the light. An all-white background will produce the loudest buzz. Turning the brightness down (cinema mode) makes for the lowest buzz. Panasonic told me it was from a bad ground in the Time Warner cable. I have not tested this by seeing if a DVD makes the same sound yet. I will bet it will. Not a solution; just a direction.