Some types of noises are normal in an LCD, LED, and/or Plasma Television. You will need to determine the type of noise to properly troubleshoot the issue.
Increase the volume to a setting between 30 and 50. Listen for the popping/cracking noise to see if it is coming from the TV speakers or inside the cabinet.
Check multiple channels and inputs.
If yes, there may be a problem with the TV speakers and would require service.
If no, there may be a problem with the channel itself. If this only occurs with a disc or program, it could be an issue with that disc or program. It may be necessary to unplug the cables being used and swapped for a new set of cables.
If not, it is normal for the television cabinet (Television case) to expand and contract due to varying heat temperatures and this may result in the cabinet producing a popping or cracking noise.
Note: The cabinet may vibrate if the volume level is set too high.
It is recommended that the TV volume be set to a moderate level. If the cabinet is constantly vibrating at a moderate volume setting, it may require service. A service bulletin was issued for some models to correct a cabinet vibration issue. Check for available service bulletins based on the model number. If there is no service bulletin listed for the model, but it still vibrates all the time, it still may require service.
The volume level may be fluctuating and causing the device to experience higher volume levels during commercials or background noises. Try to activate the Auto Volume feature if the device has one. This is located in the Audio menu of the television. Strong bass or background noises could cause a slight vibration in the cabinet. This is normal at higher volume levels.