Sharp noise from lg g4

[AC Question]

Lately I've noticed a sharp noise randomly coming from my lg g4 it sounds like a high pitched note and it only lasts a second. I can't figure out why it does this and my phone is on vibrate. There are also no notifications popping up when this happens. It happens almost everything other day or every third day. Any ideas?

 

[Tim1954]

Perhaps a persistent notification? Look in accessibility for notifications reminders... You may have something turned on there?