Sound recording

(engineering acoustics) The process of recording sound signals so they may be reproduced at any subsequent time, as on a phonograph disk, motion picture sound track, or magnetic tape.

The technique of entering sound, especially music, on a storage medium for playback at a subsequent time. The storage medium most widely used is magnetic tape. See also Magnetic recording.

Monophonic

In the simplest form of sound recording, a single microphone picks up the composite sound of a musical ensemble, and the microphone's output is recorded on a reel of ½-in. (6.4-mm) magnetic tape. This single-track, or monophonic, recording suffers from a lack of dimension, since in playback the entire ensemble will be heard from a single point source: the loudspeaker.

Stereophonic

An improved recording, with left-to-right perspective and an illusion of depth, may be realized by using two microphones which are spaced or angled appropriately and whose outputs are routed to separate tracks on the tape recorder. These two tracks are played back over two loudspeakers, one each on the listener's left and right. Under ideal conditions this stereophonic system will produce an impressive simulation of the actual ensemble. See also Stereophonic sound.

Binaural

In this system, two microphones are placed on either side of a small acoustic baffle in an effort to duplicate the human listening condition. The recording is played back over headphones, so that the microphones are, in effect, an extension of the listener's hearing mechanism.

Multitrack

To give the recording engineer more technical control over the recording medium, many recordings are now made using a multiple-microphone technique. In place of the stereo microphone, one or more microphones are located close to each instrument or group of instruments. See also Microphone.

In the control room the engineer mixes the outputs of all microphones to achieve the desired musical balance. As a logical extension of this technique, the microphone outputs may not be mixed at the time of the recording, but may be routed to 16 or more tracks on a tape recorder, for mixing at a later date.

When many microphones are so used, each instrument in the ensemble is recorded—for all practical purposes—simultaneously. The complex time delay and acoustic relationships within the room are lost in the recording process, and the listener hears the entire ensemble from one perspective only, as though he or she were as close to each instrument as is each microphone. Electronic signal processing devices may not be entirely successful in restoring the missing information, and the listener hears a recording that may be technically well executed, yet lacking the apparent depth and musical cohesiveness of the original. However, the multitrack technique becomes advantageous when it is impractical or impossible to record the entire ensemble at once stereophonically. See also Sound-reproducing systems.