(en passant=in passing) are a different type of complication that will automatically strike the hours, quarters, and possibly the minutes or half quarters.
These, of course, should be distinguished from alarm watches, that are set to make a sound at a given time, and which use very different striking mechanisms than repeaters and sonneries (though some models from Blancpain, Breguet, and Ulysse Nardin have tried to be exceptions to this last)
Cheers,
TM