Random chime noise on iPhone

I have turned off all notifications and reboot and updated and everything my phone keeps randomly making this sound or chime. Random all times of the day. I searched for months now and I’ve talked with apple bar no one seems to know what it is. Or they tell me to reboot it or turn notifications sounds off well that’s not fixing where the sound comes from. Can someone please help me. I’m driving myself crazy trying to figure this out. I even deleted all my apps because they kept saying it could be an app well I had no apps and it still happened. Help!