Analog recording

Analog audio recording began with mechanical systems such as the phonautograph and phonograph. Later, electronic techniques such as wire recording and tape recorder were developed. Analog recording methods store signals as a continuous signal in or on the media. The signal may be stored as a physical texture on a phonograph record, or a fluctuation in the field strength of a magnetic recording. This is different from digital recording where digital signals are quantized and represented as discrete numbers. The phonautograph is the earliest known device for recording sound. The phonograph was the first machine used to capture and reproduce analog sound, and was invented by the well-known inventor Thomas Edison in 1877. Edison incorporated various elements into his Phonograph that would become staples that can be found in recording devices to this day. For a sound to be recorded by the Phonograph, it has to go through three distinct steps. First, the sound enters a cone-shaped component of the device, called the microphone diaphragm. That sound causes the microphone diaphragm, which is connected to a small metal needle, to vibrate. The needle then vibrates in the same way, causing its sharp tip to etch a distinctive groove into a cylinder, which was made out of tinfoil. In order to playback the sound recorded on one of the tinfoil cylinders, the recording process is essentially reversed. As the cylinder spins, the needle follows the groove created by the previous recording session. This causes the needle to vibrate, and then the diaphragm. This vibration comes out of the diaphragm, which is now functioning as a sort of sound amplification device, much like the bell on any wind instrument. The result is an audible reproduction of the originally recorded sound. Edison's phonograph was the first of its kind, but drawbacks were nevertheless obvious. The biggest of these, and the one that ended up being fixed first, came from the physical contact between the phonograph needle and the tinfoil diaphragm. Because the needle had to continually make contact with the groove in the diaphragm every time the recording was played, the groove would wear down. This meant that every single time a recording was played, it was one step closer to being gone forever. Another problem with the phonograph was the permanence of its recordings. Unlike music today, which can be edited endlessly, the music captured by phonograph machines were single-take, live recordings. The last problem with the phonograph was related to fidelity. Fidelity is the similarity/difference between the original recorded sound, and that same sound after it has been reproduced by a playback device, in this case the phonograph. As can be expected from such an early audio recording machine, the fidelity of Edison's phonograph was extremely low. This lack of sound quality is why the phonograph was originally used to record speeches, meetings, and telephone calls, rather than music.