Labels:text | black and white | document | paper | font OCR: Note: terms follo wed by an asterisk (*) have individual artides. acoustic feedback - h LP-record playing, an undesirable sound that is caused by vibrations from the loudspeaker creating extra vibrations in the cartridge stylus acoustic suspension - A type of loudspeaker in which the motion of the woofer cone is stabilized by air pressure within the sealed cabinet. AM (amplitude modulation*) - A method of broadcasting in which the desired audio or video signal modulates the amplitude of a "carrier"signal. antenna* - An array of metal rods or wires used to intercept radio waves and convert them into electrical currents. bandwidth - The range of frequencies over which a device operates effectively. bass - The lo west audible frequencies, between approximately 20 and 200 cycles per second. bass reflex - A type of loudspeaker whose low-frequency response is augmented by sound waves emerging from within the cabinet via a port or freely suspended cone. Also called a "ported" or "vented "speaker. bias - h tape recording, an ultrasonic signal that is mixed with the audio signal during recording. Bias reduces noise and distortion and affects the frequency response. binaural - Stereo recordings that are made with microphones mounted in a dummy head and intended for playback through headphones. cartridge (cartridge, stereo *) - The phonograph pickup, consisting of a stylus assembly and the mini ature circuits that transform stylus vibration into an electrical signal. CD (compact disc*) - A digitally encoded record , aluminized to reflect light and played with a low- po wer laser. A 12-cm (4.7- in) CD contains up to 74 minutes of stereo sound. CD-I (compact disc-interactive) - A "multi-media" CD combining audio, video, still pictures, and text and used in conjunction with TV. CD-V (compact disc-video) - A variant form of CD containing up to 5 minutes of video and 20 minutes of digital audio. coaxial - Refers to devices having the same center. h a coaxial speaker, the tweeteris mounted in the center of the woofer. A coaxial cable consists of a central wire surrounded by insulation and an outer wire forming a cylindrical shield against interference. crossover - An electronic filter circuit that separates low from high frequencies and channels them to the woofer and tweeter, respectively. DAT - Digital audiotape, usually packaged in a cassette. DAT employs the same digital coding and provides the same sound quality as the compact disc. DBX - An audio equipment manufacturer and developer of noise-reduction systems used in tape recording and in stereo television sound. DCC - (Digital Compact Cassette ) A cassette tape format that employs perceptual coding digital - (1) A method of representing sound waves as a series of binary numbers. (2) A tuning method for radios, in which the desired frequency is set by digital calculation. (3) A numeric display of information . direct drive - A turntable drive system in which the spindle and platter are part of the motoritself. distortion - Changes in a signal that involve the addition of spurious tones at frequencies not present in the original sound. h "harmonic" distortion the spurious tones are at integral multiples of the original frequency. h "intermodulation "distortion, discord ant tones appear at the sums and differ- ences of two original frequencies. Dolby B, C, and S - Noise-reduction circuits for consumer tape recorders. Two other circuits, Dolby A and SR, are used in recording studios. Dolby Digital - A system of five-channel surround sound for motion pictures, based on Dolby AC-3 percep tual coding . Dolby Stereo - A system of noise-reduction , equalization, and surround sound, used for motion- picture sound tracks. dropout - A momentary loss of signal in a tape recording, usually caused by wear, dust, or a tape de fect. dubbing - (1) The process of copying a recording to make a duplicate. (2) h motion-picture sound, replacing a foreign-language sound track with dialogue in the language of the audience. dynamic range - The ratio between the loudest and softest sounds that can be reproduced accurately by a recording medium. equalization - Changes in amplification at low or high frequencies, done to compensate for the limitations of a recording medium and to ob tain equally accurate reproduction at all frequencies. flutter - Unwanted variation in the speed of a turntable or tape recorder. Slow flutter, or "wow," causes musical sound to waver in pitch. FM (frequency modulation*) - A method of broadcasting orrecording in which the desired audio or video signal modulates (varies) the frequency of a "canier" signal. FMX (Extended-range FM.) - A noise-reduction system that permits hiss-free reception of FM broad- casts at large distances or with small antennas. frequency response - The principal measures of the fidelity of any sound-reproducing device. graphic equalizer - A tone-control device whose amplification can be varied by octave, using slider controls whose positions provide an approximate visual graph of the frequency response. head - The device in a tape recorder that applies the recording signal to the tape, or reads it for playback. impedance - Opposition orresistance to the flow of electrical current. The rated impedance of a loudspeaker is an average, since the impedance depends on the frequency of the signal. integrated amplifier - An amplifier containing the preamplifier and the power supply in one unit. LED (light-emitting diode) - Solid-state devices that glow when electric current is applied. loudness compensation - A tone-control process that boosts low frequencies at low volume levels, in an attempt to compensate for the ear's insensitivity to quiet bass sounds midrange - Frequencies in the range spanned by the human voice, from approximately 200 to 2,000 MD (MiniDisc) - A miniature digital audio disc, based on perceptual coding . A play-only MD is a cycles per second. miniature CD. A recordable MD is a magneto-optical disc. monophonic, monaural - Recording or playback involving only one channel of sound. multipath - Reception of one ormore reflected signals along with a direct broadcast signal, producing distortion in stereo FM and ghost images in television. multiplex - A method of accommodating two channels of information on one carrier, for example, two channels of sound in one FM broadcast. percep tual coding - An approach to digital coding that records only the portions of a sound or picture that are believed to be audible or visible. phase - The relative timing of two signals. If signals are "in phase," they are precisely synchronized . If loudspeakers are wired "out of phase," one is "pushing" when the otheris "pulling" preamplifier - The portion of an amplifier* that amplifies phono signals and includes most operating con trols. power amplifier - The portion of an amplifier that produces the high current levels needed to drive a loudspeaker. quadraphonic - Surround-sound reproduction involving the recording and playback of four channels of sound. quantization - The representation of a continuous quantity, such as a sound wave, by a series of numeric values. receiver - Generally speaking, any device that receives broadcasts. h Hi-Fi equipment, an integrated amplifier and radio tuner combined in the same chassis resonance - The natural tendency of a device to vibrate at a specific frequency. Unwanted re so nances in loudspeakers, for example, alter the sound by producing excessive response at some frequencies. rumble - Low-frequency noise caused by vibration of the motor and bearings of a turntable sampling - Part of the process of digital recording dissection of a signal in time, preparatory to quantization. selectivity - A measure of a tuner's ability to receive stations at closely spaced frequencies without mutual interference. signal - A soundwave, transmitted as an electrical waveform or its digital representation. S/N ratio (signal-to-noise ratio) - The range, usually expressed in decibels, between the loudest sound a recording medium can accommodate and its background noise level. stereo phonic - Sound reproduction that uses two ormore channels in order to represent the size or spatial distribution of sound sources. surround - Sound reproduction that surrounds the listener with sound, as in quadraphonic recording and reproduction. THD (total harmonic distortion) - A measure of all of the spurious signals added by a sound-reproducing device . tone control - A method of altering the timbre of reproduced sound by increasing or decreasing the amplification at either high orlow frequencies. track - The area on a tape where a signal is recorded tracking force - The downward force applied to a stylus to maintain uniform contact with the undulating groove wall. transducer - A device that changes a signal to a different physical form while maintaining its pattern: as in the phonograph cartridge, which transforms stylus motions into electrical signals, or the loud- speaker, which transforms electrical signals in to sound waves. transport - The portion of a tape recorder that moves the tape past the heads at constant speed. treble - The highest audible frequencies, between approximately 2,000 and 20,000 cycles per second tweeter - A small loudspeaker that reproduces high frequencies. watt - A unit of electrical or acoustical power. Electrical poweris the product of voltage and current Acoustical poweris proportional to sound-pressure intensity. woo fer - A large loudspeaker that reproduces low frequencies. wow - Slight variations in the speed of a tape orrecord player, causing the musical pitch to wobble.
