One customer (even if multiple complaints from them), or several customers?
If a single customer their receiver, sound bar, TV, HDMI or optical cable, (or even mute button) could be the issue and you'd be on a wild goose chase. If you have heard it from more than one customer that's could be an actual issue.
We used to put a customer complaint like that (unrelated to Roku development) into a suspected issue "basket", do a quick test to see if we could recreate it, and if not pend it for a second complaint, which we then escalated for a deeper dive.
The majority of those single complaint issues evaporated on their own, which of the course the customer would rarely inform us of.
