DIGITAL SOUND RECORDING

method of preserving sound in which audio signals are transformed into a series of pulses that correspond to patterns of binary digits (i.e., 0's and 1's) and are recorded as such on the surface of a magnetic tape or optical disc. A digital system samples a sound's wave form, or value, several thousand times a second and assigns numerical values in the form of binary digits to its amplitude at any given instant. A typical digital recording system is equipped with an analog-to-digital converter that transforms two channels of continuous audio signals into digital information, which is then recorded by a high-speed tape or disc machine. The system uses a digital-to-analog converter that reads the encoded information from the recording medium and changes it back into audio signals that can be used by the amplifier of a conventional stereo sound system. Digital recording provides higher-fidelity sound reproduction than do ordinary recording methods, largely because audio signals converted into simple pulse patterns are virtually immune to the residual noise and distortion that are characteristic of analog communication channels and sound recording media. In addition, many digital recording systems are designed to detect and eliminate interfering signals. In the 1980s digital compact disc recordings became available that were played by using a laser beam to optically scan digital information encoded on the disc's surface. In the late 1980s digital audio tape (DAT) recorders using magnetic tape cassettes became available for audio reproduction and recording. The DAT recorder converts audio signals into digital data on a magnetic tape by means of a microprocessor and converts the data back into analog audio signals that can be used by the amplifier of a conventional stereo sound system. The early 1990s saw the introduction of digital compact cassette (DCC) recorders, which were similar to DAT recorders but could play the older analog tape cassettes in addition to similarly shaped digital cassettes. See also sound recording.