Klaxon

Set a window and a number of sirens. They go off at random moments you can't predict.

Sound
Your musicwhen a siren goes off

Start your music first, then come back here and tap Start. Keep this screen open while it runs (the app keeps the display awake). Between sirens your music plays normally; each siren cuts in over it. On iPhone this needs iOS 17 or later. Tip: Share → Add to Home Screen for a full-screen app.