Macbook Pro 2016 15" model. The speakers often go from perfectly clear to very noticeably muffled when adjusting the volume. It often happens when turning the volume up - but it'll still be at reasonable levels. It gets muffled immediately as opposed to slowly degrading in quality which leads me to believe it's not a problem with the speaker slowly deteriorating.
It usually goes away after a few restarts.
Is this normal? How can I debug this further?