If this is happening with cable/sat/broadcast only, then it may be how the audio signal is being sent. If you use a box, you might try calling your cable/sat company to have the box reset/refreshed, or have an update applied. This can usually be done over the phone with the service people at your cable/sat provider.
If this is happening on other inputs, such as DVD/Blu-Ray or other inputs, then it may be an issue with the television itself. However, try to see if updating your box may help .
I'm not sure how to describe this issue, except to say that there seems to some sort of audio problem when dialogue is not being spoken in the program I'm watching. Rather than having "normal level" background noise between the time that one character stops speaking and the next character starts speaking, it's as if the audio drops out. So the soundtrack ends up seeming choppy, as if someone's muting and unmuting. It's most noticeable in a slow, quiet scene w/ intense one-one-one dilaogue. Can anyone help me out?