My macbook pro randomly beeps, accompanied by a brief dimming of the screen. I can't detect any pattern or any trigger to explain it. Does anyone know what causes this?
This was driving me crazy for quite a while and I see other people have had the same issue.
I think I figured it out. It's nothing to do with auto dimming in response to ambient light or power management and no amount of mucking around with your mac's notification settings or restarting your mac, or using safe mode will fix it. I even got the same strange notification if no apps at all are open. The cause appears to be related to the shoddy interaction between the mac and the windows world. If you are using an outlook account on your mac you may have noticed strange behaviors in both apple mail and apple calendar and they have to do with poor interaction between the two worlds; bugs that nobody wants to take responsibility for. The clue to understanding these random notifications has to do with the fact the sound is a bit like the new mail alert. You cannot stop it with mac settings. Somehow, microsoft is able to shove these notifications onto your mac even when apple mail is not even open. To stop them you will need to use a browser to go to your outlook settings in your microsoft account. Under general > notifications make sure all these settings are turned off (ie unchecked):
