A
Welcome to Android Central! Which phone? What occasional sounds do you get?
Have you recently changed the password for any email account? Or have you added a new account in the Gmail app? It's possible that beep is related to an account not being able to sync on the Gmail app.I finally made progress on this: I found that when I turn off all Gmail notifications, I no longer get untraceable beeps and vibrations. But still, when I leave Gmail notifications on, I get beeps and tones at times when there is no new email.
You could try creating a widget for the notification log and see if you can get more information next time you get this sound. Unfortunately this is not so easy on Samsung devices and you'd need to use a third part app, like More Shortcuts, or a custom launcher, like Nova, to create the widget.Good thoughts, which had not occurred to me. But nope. No new password, and no new account.