Town Crier
From think.pedia
The Town Crier system was created to help people in the Metro Areas manage their schedule. As a result of The Plagues many individual lack access to a clock or an alarm clock. The Town Crier alerts the entire Metro Area of certain key times that vary by location. They usually include a wake-up timer, noon timer, and quitting timer. The Town Criers also deliver emergency announcements to the Metro Area.
The Town Crier system relies on a variety of sounds producing Differents in order to sound the needed alarms.