Hourly segments to voice or tone the whole point of time, do not open the phone screen at the time, with the time to listen to grasp, around chatting to people hear chime will know the advance and retreat, so that we have the opportunity to exit.

There are other ideas please tell here, thank you
 iOS version https://itunes.apple.com/us/app/hourly-chime/id1056483583?l=zh&ls=1&mt=8