page_title: Sound recording and reproduction
section_title: Tape
hierarchical_section_title: Sound recording and reproduction / Technology / Tape
context_page_description: Sound recording and reproduction is the storage of sound and playing it back so that a person can hear the same sound more than once. It is a process wherein sound waves are captured by a machine. The machine converts the waves into electrical signals or digital data, that are then stored on recording media. The sound can then be played back by reversing the process.
  Most recordings are of music, people speaking or singing, and sound effects. They are usually used for entertainment, or for scientific and historical reasons.
  Sound is recorded onto a medium by different methods. The ways that recordings are made have changed a lot since sound was first recorded.
context_section_description: In the late 1930s the tape recorder appeared. Tape recorders use a magnetic tape as a medium, with a recording head to store the sound on the tape. Sound waves are converted into an electrical signal inside the recorder. This signal goes into the head, where it changes the polarity of very small magnets. Tape moves past the head at a constant speed, and its magnetic particles are rearranged by these magnets to a pattern that represents the sound wave. These magnetic patterns are much like the small grooves of a cylinder or disc record in the way that they represent the vibration energy of sound waves.
  When a tape is played back, it runs past a playback head which reads the magnetic patterns off the tape and converts them back into an electrical signal. The electrical signal can then be converted into sound waves or copied to some other kind of sound-processing machine.
  A magnetic tape is divided into several tracks. Each track uses up part of the width of the tape, and can store a completely different recording that can be played back at the same time as the other tracks. A two-track tape has one track on half of the tape and another track on the other half. A four-track tape has four tracks all lying next to one another, like a highway with four lanes. Most tape recordings today are stereophonic (or stereo), meaning that they have two tracks which are meant to be played together. Usually one is played on the listener's left side and the other is on the listener's right side, to match the listener's two ears.
  Early tapes were wound flat on a storage reel and transferred to a take-up reel as they were recorded or played. After recording or playback, they were rewound so that they were stored only on the storage reel. This kind of system is usually called reel to reel today. It is still used today for some professional recording and playback, but for home use reels were mostly replaced with other kinds of tape in the 1970s. Cassettes are small cartridges containing two reels inside. Cassettes move a four-track tape in either of two directions, corresponding to their side A and side B labels. The reel on the left contains the unplayed or unrecorded tape, and the reel on the right contains the tape that has already passed the recording or playback head. When you turn the cassette over, the tape still moves from left to right, but this is really the opposite direction. The "side A" recording plays two tracks as stereo, and the "side B" recording plays the other two.
  Eight-track tapes were popular for a while in the 1970s and 1980s. Eight-tracks work much like cassettes, but the tape is a loop: it repeats after being played all the way through. Because it has eight tracks, there are four programs to select from, each in stereo. Eight-tracks are not very popular anymore, but can still be found in hobbyist collections.
  Professional tape-recording systems may have even more tracks, or might use them differently. Usually a system like this is designed to allow someone to mix the tracks in different ways than they were originally recorded. However, there is a kind of recording called quadraphonic that uses four-track tape to play four different tracks at the same time. A good quadraphonic recording can sound much more "real" than stereo or monophonic recordings.
caption: A typical Compact Cassette
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