You can use tasker, trigger and/or ITTT
+1
Yes, but he wants it automatically coded to track the new Zmanim as they shift...
(i.e. if it "dings" at Shkiah, then the app automatically calculated/hooked up with another time app too know each day when daily Shkiah is..)
Should be simple to add audio alerts to a Zman calendar!
The 'kuntz' would be for people to add their own custom times... (i.e. personal lunch break alert to always beeps 45 minutes after Chatzos each day)