Demos by PIRA

  3C20.15Galton's whistle: Compressed air whistle.
  3C20.16Steel spring pendulum, inverted, vibrates at 10 Hz.
  3C20.16Limit of audibility: Set of rods that ring at different frequencies.
  3C20.30Siren: large, electric motor driven.
  3C20.30Compressed air jet blows through spinning disk with holes.
  3C20.40Savart's wheel: Toothed wheel and cardboard or air jet.
  3C20.40Sprockets on shaft rotate against a card to make sound.