you don't, really — you start it and attend. fifteen pendulums, each swinging a little slower than the last.
at the edge of each swing a pendulum strikes its note. at the start they strike together: a chord.
then they drift — the periods are different, so they fall out of step. for a while it sounds like chaos.
but the lengths are chosen so that after one full cycle they all return to the same beat at once. order comes back. it always comes back.
cycle — how long the return takes. longer = more wandering before the homecoming.
this is what a phase relationship looks like when you can hear it. nothing is lost in the drift. the alignment was always going to happen — it was built into the lengths from the beginning.