Safe mode is designed to restrict access to third party applications. Since it doesn't happen in safe mode it seems there is a third party app causing the notification sounds. You'll have to figure out which one it is and disable notifications from it.
I'm pretty sure I'm pretty sure it's
to do with Always on function. I switched this on last week and have been beset with constant unnoticed beeps. I force stopped it just now and the problem is fixed
Samsung repeatedly saying the same thing is not fixing the issue can we get a resolution I love my s9 but the lack off sleep and constant interruption is really upsetting can we get an update that will fix this???????
I have the same issue. Mine usually does it when i connect to or from my car. and the notifications will not stop dinging for at least 2 minutes with multiple different bells. It will go non stop with at last count was 75....yes 75 dings back to back with no pauses....also with different bells......ding ding ding ding dong dong dong ding ding dong dong just continually. aalso it locks up while driving.
@Joshua tree, Can you provide us with your model number, base band version, and the carrier your device is being ran on?