Seemingly randomly throughout the day, my mac will "whoosh" at me. I set up Messages, but whenever I switch to Messages after the whoosh, I don't have any new messages and usually my buddies are set to Away status anyway.
Notification center is empty with "No new notifications."
I don't have the mail client set up or running, so it can't be that. I do use Reminders and sometimes put things in the calendar, but I don't think those are whooshing at me.
What is whooshing at me and how do I make it stop?