Grand Pocket Orchestra
Coordinated start test
Open this page on several phones. When any device taps Arm, the server picks a synchronised T0 ≈ 7 s in the future and every connected client schedules the same click pattern at that instant. Flam means the clocks haven't converged.
Required once per session on iOS Safari; no audio happens until you do. Also asks for microphone permission so this device can take part in chirp-ritual latency measurements (mic is only opened during a ritual).