Most people who complain of this issue tend to have their tv setup on a cable/satellite box. The problem is sometimes only noticeable when switching from SD to HD channels. If you are using a set top box check to see if you can increase the audio output from the box (if it is variable) and lowering the TV's volume. This will give you a cleaner sound since the amp is not driving the audio at full blast and should reduce the pop. The pop itself I suspect is the audio signal being cutoff then coming back to the TV. This can be due to the different audio signals available on channels such as Dolby or stereo. The scene change scenario doesn't really agree with my theory and could potentially be a problem with the TV but I would definitely try my suggestion first. If you cannot clear out the pop with my suggestion, write me back but include the box model (if applicable, tell me what you are using if not) and the model. I will try to see if there is a setting we can change on the source to make it output at a constant resolution and audio signal.