You do NOT have that remote, if you own a Roku tv, that remote is useless without outboard roku like a ultra, express, or real roku soundbar. So your brand of roku tv is ONN? You roku tv remote has written on it Onn Roku TV, not Onn Roku like the one I linked too.
This voice it can't be just saying the soundbar is off, it has to be telling you every move you make with roku tv remote, go into the roku tv settings> accessibility> scroll down to Screen reader> off
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