Hourly segments, voice or tone whole point of time, do not open the mobile phone screen at the time, with time to listen to the master, around chatting to people who hear the clock 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