I'm new to the Mac, and I'm experiencing a strange problem ever since updating to Big Sur. About every 30 seconds, I will hear a soft dinging noise. If I turn VO off, this sound stops, but as soon as I turn VO back on, the 30-second intervals start again. I thought it might have something to do with notifications, but I've cleared them all, and the sound is still occurring. Does anyone know what this is and how to stop it?