D defs.my
Entry 1 sense Webster, 1913

Phonautograph

· Pho·nau·to·graph · IPA /fənɔtəɡɹæf/
01 n. An instrument by means of which a sound can be made to produce a visible trace or record of itself. It consists essentially of a resonant …
  1. 1.
    An instrument by means of which a sound can be made to produce a visible trace or record of itself. It consists essentially of a resonant vessel, usually of paraboloidal form, closed at one end by a flexible membrane. A stylus attached to some point of the membrane records the movements of the latter, as it vibrates, upon a moving cylinder or plate.(Physics)