There’s not much info to go on with your question, but given that the Logitech Review is mentioned…
The Review has HDMI and Optical audio outputs. Intermittent audio can be electronics in the Review, bad cable or contacts, or the TV itself.
So it’s time to proceed to fault isolation, going from least expensive to most and stopping when the problem resolves
Start by reseating the HDMI cable at both ends; check to see if the contacts are dirty.
Try a known working HDMI cable; you don’t need anything special or up to date, as the Review is old and therefore doesn’t take advantage of things like networking over HDMI
Use another HDMI source (borrow if you don’t have one) to see if it’s the Review.
Finally, see if another HDMI TV eliminates the problem.
Keep in mind that the Review is old, and Google no longer supports the Google TV software platform. If the Review itself has failed, you can get a refurbished replacement on eBay. If you are feeling ambitious, intermittent failures in audio that are in the Review are most likely failing solder joints, loose wires or cracked circuit boards. Try tapping the unit and seeing if the problem exhibits itself (or gets better). If so, and you are up for doing it, open it and look for the above faults. Re-soldering bad joints can work…and you can always try reselling a failed unit on eBay for parts if that’s more appropriate.