phonautograph

The phonautograph is an early device invented in the 1850s that was used to visually record sound waves. It works by capturing sound vibrations through a diaphragm that moves in response to sound, which then traces these vibrations onto a surface, like a soot-covered paper. Unlike modern audio recording devices, the phonautograph could not play back sound; it only created a visual representation of audio patterns. This invention laid the groundwork for future sound recording technologies and helped advance the understanding of acoustics and sound reproduction.