Why is my Moto X sounding its ringtone so often?

[AC Question]

It sounds when it turn it on, when an e-mail comes in, when text comes in, and it sounds when NOTHING happens. It shows a little envelope for an e-mail, a square face for text, etc, but often I click it on in response to the sound and find there is nothing new, an envelope (for email) shows under the time of day, but there is no new e-mail. How do I set it so this stops?
Thanks.