Hold your phone near something that repeats — a 3D printer laying down infill, a washing machine, a treadmill — and this finds its rhythm, then builds music locked to it.
Ready. Listening takes about 12 seconds.
How it works. It listens for about 12 seconds, measures the gap between repeated sounds, then picks a musical tempo that divides evenly into that gap — so every beat lands with the machine. The microphone switches off before the music starts: otherwise the phone would hear its own music and follow that instead, and iPhones route sound to the earpiece whenever a mic is live.