You could start a [short] countdown and configure an event to play the sound when the countdown starts, or when the countdown is near the end.
Create a new event on the Events tab and select "Create a new event from scratch". Give the event a description, and set the Trigger to "The clock ticks". Set the Conditions to:
(state = 1) and (secondsLeft = 0)
Press the New Action button and add an action that plays your sound file. Press OK to save the Event. Then move the event (using the "Sort Events" button) to the top of the list of events.
This will play the sound when the countdown hits 0. If you want it to play at, say, 5 minutes before the tournament starts, change the Conditions to:
(state = 1) and (secondsLeft = 300)