Ideally, the only buzz your LCD TV should produce is positive feedback about what's on the screen -- unlike the cathode ray tube televisions of yore, liquid-crystal displays do not naturally hum, even subtly. Various problems, including both external factors and internal device issues, can cause unwanted buzzing; to remedy the noise, start with simple solutions, before calling in the professionals.
Mute your LCD TV and listen closely. If the buzz stops when you mute your set, the issue is likely audio related. In this case, check all of the TV's external audio connections, including composite and coaxial cables. Ensure that the cables are securely plugged in to their respective inputs.
Adjust the volume settings on external devices connected to the TV, if available. Some devices -- such as cable boxes, sound systems and DVD or Blu-ray players -- feature their own volume controls. If the volume on these devices is too high, your TV may buzz during operation.
Turn the TV off, then unplug the device from the power outlet. Let the TV rest for at least 60 seconds before plugging it back in and powering it on. This may remedy buzzing related to the TV itself rather than external devices.
Move electronic devices that may cause interference away from your LCD TV. Appliances such as microwaves, power generators, hair dryers, sewing machines, garage door openers, electric drills and vacuum cleaners may produce electrical interference during operation, causing your TV to emit buzzing sounds.
Adjust your TV's brightness settings. In some cases, the capacitors that supply power to your LCD TV's fluorescent backlight emit an unintentional buzz. Tweak the brightness and backlight settings of your TV via its on-board menu until you no longer hear a noise.