Phonautogram
The phonautogram, or phonautograph tracing, was a method used to transcribe sound waves onto paper using a device patented by Édouard-Léon Scott de Martinville (of France) on March 25, 1857. This method was intended to be used for the purpose of studying sound wave patterns for scientific purposes, and had no means of playback. However, later inventors realized that the automatic transcription of sounds into a physical pattern on some medium could in theory be used to both record and play back sound, eventually leading to the phonograph. Still, no means of playing back the original phonautograms of the 1850s and 1860s (of which several were preserved) existed until 2008, when researchers managed this feat with a high-resolution scan and computerized image processing.
