Organ pipes begin notes one brief harmonic above their sustained pitch

Evidence

Careful listening to pipes voiced with a chiff will reveal that open pipes start briefly an octave high since their first overblown mode is the second harmonic, and stopped pipes start an octave and a fifth high since their first overblown mode is the third harmonic. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1446

Categorization

• CANDY: A fun, tweetable fact: organs briefly start each note an octave high - a built-in flourish in the instrument’s very physics.