Each Rink must be provided with a suitable sound device that will sound automatically at the conclusion of each period of play. Should the sound device fail to sound automatically when time expires, the determining factor as to whether the period has ended shall be the Game Clock. For more information refer to League Regulations.
Regel 4.2: Timing Devices
Each Rink shall be provided with some form of electronic game clock for the purpose of keeping the spectators, Players, Team Personnel and Game Officials accurately informed as to all time elements at all stages of the game including the time remaining to be played in any period and the time remaining to be served by penalized Players on each Team.
The game clock is activated by facing-off of the puck by an On-ice Official and shall be stopped by the whistle of an Off-ice Official. Time recording for both game time and penalty time shall show time remaining to be played or served. The Game Time Clock shall measure the time remaining in tenths (1/10) of a second during the last minute of each period. For more information refer to League Regulations.