The storage of sound for duplication, audio recording is produced through mechanical, electromechanical, or electronic technology. The industry was pioneered in the United States, which is also the largest consumer of long-playing (LP) records, audiotapes, and compact discs (CDs). With steady advances in the recording equipment, disc and tape sales top 3 billion dollars annually. The first phonographs, invented by Thomas Alva Edison in 1877, played tinfoil-wrapped cylinders. Later inventors substituted wax. Emile Berliner's gramophone disc records, invented in 1887, made many improvements in Edison's invention possible—for example, easier mass production and enhanced fidelity. Lee De Forest invented the amplifying, three-element electron tube, called the audion, in 1907, and phonographs using amplifiers with one or more tubes appeared in the 1920s. De Forest also demonstrated sound-on-film talking movies as early as 1923. (See also De Forest; Edison; Motion Pictures.) Audio Recording EquipmentAudio recordings, and the equipment used to make them and to play them, come in many forms. In the late 1940s manufacturers introduced phonograph discs that revolve at either 45 or 33 1/3 revolutions per minute (rpm). Just as they made collections of 78-rpm (the old standard) discs nearly obsolete, CDs in turn replaced LPs in popularity in the late 1980s. In addition to the improved sound of CDs, they can store up to 80 minutes of recorded music on a side, while LPs offer only 60 or 70 minutes on two sides. (See also Compact Disc; Phonograph.) Analog magnetic tape recorders are available in open-reel or cassette formats. Open-reel recorders feature greater fidelity and are easily edited. Cassettes, which were designed for more convenient storage and use, became a high-fidelity medium in about 1970. (See also Tape Recorder.) Digital audiotape (DAT) is a refinement of videotape technology (see Video Recording). DAT recorders play cassettes that resemble, but are smaller than, analog audiocassettes. Because DAT technology is digital, it can provide fidelity of sound that is superior to recordings made for analog cassette recorders. Rerecordings of DAT tapes closely resemble the originals in quality, while analog duplicates suffer substantially degraded quality. Recording companies perceive the duplication advantage of DAT as a disadvantage. They believe the availability of excellent amateur-produced recordings would encourage piracy and drastically reduce sales of commercial recordings. (See also Electronics.) THE RECORDING INDUSTRYThe recording industry plays an integral part in the music and motion picture branches of the entertainment industry. The techniques used to record sound in each medium are vastly different. Motion picture sound, for example, must be synchronized with the visual performances so it is transferred to film, rather than to discs or cassettes. Music RecordingThe two basic approaches to recording music today are the documentary-style and the studio-type recording. On-site equipment is most often used to record classical music and live concerts of popular music. Most rock musicians prefer to record their music in studios, where they can experiment freely, and other pop performers may rely upon electronic gimmicks to alter their sound. Documentary-style recording. In this method, recording engineers set up portable equipment at the recording site. They may employ one or more microphones with or without a microphone mixer. Often they use simple two-, four-, or eight-track recording machines. With only two microphones positioned at 90- to 120-degree angles to the performers, engineers can record an entire orchestra. Sometimes recording engineers separate the microphones with a screen made of special acoustical insulation in order to approximate the binaural (two-eared) experience of human hearing. Sound personnel may mount a microphone on a tall stand to pick up the airborne waves and the wall-conducted waves. The opposite effect is obtained by placing a microphone on a low tripod. The objective is to permit only one sound path to the microphone, otherwise echoes tend to cloud the original signal. Studio recording. The central components in this kind of recording are tracks—narrow, parallel strips that run the length of the surface of audiotape. A multitrack recorder can tape each track separately. That way, a singer might record on one track one night, the guitarist on another the next night, and the percussionist on still another the third night. The recording engineer can play back the individual tracks at whatever volume is desired for each. The volume of one track does not affect that of any other track. The engineer can also re-equalize (change the ratio of high sounds to low and middle sounds) one track at a time or create a wholly new track by mixing two of the original tracks. In fact, multitrack recording and mixing are routine procedures that allow all kinds of enhancement after the original recording dates. Studio recording involves the use of several pieces of equipment: a special, acoustically enhanced recording environment (the studio itself); a microphone for each recording voice and acoustic musical instrument; line preamplifiers for electronic instruments; a multitrack mixing console that permits the engineer to adjust the volume of each input separately and a multitrack recorder to store the output signal from the console. This recorder might be digital or analog. For music recording it usually has eight or more tracks; however, many studios are equipped with 24- and 48-track machines. Recording for Motion PicturesDocumentary films may be shot with “single-system” or sound-on-film (SOF) cameras that record a magnetic or optical track running parallel to the picture area. Editing such film is difficult, however, and the film's sound quality is inferior. Inventors solved these problems with a technique called double-system sound. Although the sound tape recorder and film camera are separate pieces of equipment, an electronic synchronization signal assures correspondence between the two during filming. Laboratory personnel copy the tape to magnetic film with the same proportions as the picture film. They may also add sound effects in the studio. During editing picture and sound films are locked side-by-side into an editing console. When one film is cut by an editor, the others must be cut at the same place. If synchronization is lost, it can be regained by advancing one film or another. Back at the laboratory, the picture and sound are married to create a single film with a synchronous soundtrack. This film, called the release print, is what viewers see and hear on television or in the theater. It is equipped with either an optical or a magnetic soundtrack. Optical soundtracks consist of one or more narrow stripes at the edge of the film. Viewers cannot see these tracks on the screen because they are outside the projected area of the film. There are two basic types of optical soundtracks—variable density and variable area. Many versions of each type are used. A variable-density sound stripe can vary in color from opaque black to almost clear. An exciter lamp projects through this stripe onto a photoelectric pickup. Depending on the hue of the film, the light falling on the pickup changes in intensity. These changes cause the pickup to send a proportionate, varying current to a sound amplifier. The amplifier fortifies the signal and feeds it to speakers. Variable-area stripes are composed of a clear center of variable area edged with opaque black. Width differences in the clear center determine the final differences in sound. An exciter lamp shines through the track onto a photoelectric pickup. Like the variable-density stripe, the variable-area stripe constantly alters the amount of light falling on the pickup. From this point on, the two techniques are identical. A magnetic soundtrack is an iron oxide coating on the edge of the film. A tape head in the projector reads the track. While optical soundtracks are permanent, the magnetic track can be erased for rerecording. |