Analog sound reproduction is the reverse process, with a bigger loudspeaker diaphragm causing changes to atmospheric pressure to form acoustic sound waves.ĭigital recording and reproduction converts the analog sound signal picked up by the microphone to a digital form by the process of sampling. In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, which is then converted to a varying magnetic field by an electromagnet, which makes a representation of the sound as magnetized areas on a plastic tape with a magnetic coating on it. The process is reversed in sound reproduction, and the variations stored on the medium are transformed back into sound waves.Īcoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). Sound recording is the transcription of invisible vibrations in air onto a storage medium such as a phonograph disc.

The two main classes of sound recording technology are analog recording and digital recording. Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. Frances Densmore recording Blackfoot chief Mountain Chief on a cylinder phonograph for the Bureau of American Ethnology (1916)

Spy voice recorder