Signal to switch drivers during :25 - :35 second period?

I can’t find it in the game manual, is there going to be some official signal that drivers should switch control during the :25 - :35 second period during the Teamwork Match and Robot Skills challenge?

Yes, for events using the Tournament Manager software, the system will produce a sound with 35 seconds and then again with 25 seconds remaining in the match to remind the drivers to switch the controller. Since this sound may get lost in the excitement of the game, it is also a best practice for the referee and/or emcee to remind the students to switch the controller at this point in the match.