Audio/sound cuts out and stays off intermittently on several channels

Examples applies to channels 247 TBS HD, 237 Bravo HD, 282 Animal Planet HD, 265 A&E HD from our experience.

After a channel is selected and from a couple to several minutes of being on, the audio cuts out intermittently on the listed channels.  Returning to a previous channel and immediately returning to the affected channel returns the audio for a short time before it cuts out again.  This problem occurs anytime during the day/night and has been going on for several months.  Keeping the affected station on has not returned the audio to the channel.

Unit is a Samsung smart TV connected with HDMI cable to a non-Genie DirecTV DVR box and no external surround sound system.
- DVR has been reset, card removed and DVR restarted, power cable removed and DVR restarted with no result
- Confirmed DVR box audio is set to English Dolby Digital
- Confirmed latest software for DVR and Samsung TV has been successfully installed on each unit

Help me understand why the sound cuts off on these channels and what are the next steps to resolve this problem.  Thanks.