My ears were ringing.
Actually, my ears were burning. The ringing usually only occurs when I get smacked. Thankfully, it has been a while since I've been smacked. If
@Jack N can list all of the devices and the TV/Projector used in the system, I could try and help out. But, as
@William Lemmerhirt mentioned, first make sure the AV10’s eARC port is being used to connect to the TV/Projector’s ARC/eARC port.
In the AV10, make sure the HDMI Control function and ARC are ON. They will both need to be ON if the TV/Projector supports ARC but not eARC. Different TV/Projector manufacturers have the annoying habit of calling HDMI-CEC anything but HDMI-CEC. So, knowing what it is called in one's TV/Projector will lessen the difficulty of using it.