Glossary – D
D/A – Abbreviation for Digital to Analog conversion, which changes digital data numbers (digital audio signal) into discrete voltage level. The reverse process of A/D.
Daisy Chain – The connection of three or more devices in a series, where the audio signal passes through one device to reach a second, and through the second to reach the third, etc.
D-Sub Connector – Abbreviation for “D-subminiature connector,” a D-sub is a multipin connector that is most often used to connect a computer to a VGA monitor, but also used occasionally in digital audio applications in the recording studio.
Damping – The reduction of energy in a vibrating system, through friction. Can refer to the reduced amplitude in an electrical signal, or the stifled vibrations of a musical instrument (for example, the damper pedal on an acoustic piano).
Damping Factor – Describes an amplifier’s ability to restrain the pushback motion (back-EMF) of the loudspeaker cone when the audio signal stops.
DAW – An abbreviation for Digital Audio Workstation, a device or software program designed for recording and mixing audio digitally.
dB – An abbreviation for decibel, a measurement ratio that compares signal strengths (usually audio levels).
DBX – A series of noise reduction systems, named for the company that developed them. DBX noise reduction has been less commercially successful than the more widely known Dolby systems, but is still found on occasion in recording studios.
DC – see “Direct Current.”
Decay – The second stage of the four stages of a sound (Attack, Decay, Sustain and Release, or ADSR), the decay of the sound is its gradual reduction in volume after reaching its peak in the attack stage.
Decca Tree – A stereo microphone placement technique involving three microphones (usually omnidirectional) placed in a “T” pattern. Commonly used in miking choirs, orchestras and other large ensembles, but variations of the Decca tree technique are also being used today in surround sound situations.
Decibel – (abbreviated “dB“) The ratio measurement of two levels according to a scale where a certain percentage change comprises one unit. Most often used to describe audio levels.
De-esser – An audio compressor designed to reduce the volume of sibilant sounds and frequencies, especially those produced by pronouncing the letter “s.”
Degaussing – The process of demagnetizing an object. In the context of audio, degaussing essentially erases the recording on magnetic tape.
Delay – 1) An process by which an audio signal is recorded to a medium or device, reproduced at a time delay, then mixed with the original, non-delayed signal to create a variety of effects such as a fuller sound, echo, chorusing, flanging, etc. 2) A signal processor that creates delay effects.
Demo – A preliminary recording that is intended to give the listener an idea of how a song could sound in a final production. A demo usually involves minimal tracking or production, almost like a “rough draft” of a recording.
Detune – To purposely cause an instrument or signal to play out of tune (usually slightly). This effect can be used for a number of purposes in the studio, but is often used in “double-tracking,” blending the detuned instrument/track with the original to create a fuller sound.
DI – see “Direct Injection.”
Dialogue – The spoken word recorded in film/video sound, commercials and instructional recordings.
Diaphragm – The part of a microphone that moves in response to sound waves, converting them to electrical signals.
Digital Audio Workstation – (abbreviated DAW) A device or computer software that records and mixes audio digitally and creates digital audio files. A DAW can be a standalone unit or an integrated set of components, but today they are most commonly found as “in-the-box” software programs run from a computer. The most common DAW program found in recording studios is Pro Tools; other commonly used programs include Reason, Ableton and Logic.
Digital Multimeter – see “Multimeter.”
Digital Recording – The process of converting audio signals into numbers that represent the waveform, then storing these numbers as data.
Digital Signal Processing – (abbreviated “DSP”) Any signal processing done after an analog audio signal has been converted into digital audio.
Digital to Analog Converter – (abbreviated D/A) A device that converts the digital data of digital audio into voltage levels that approximate the original analog audio.
DIN Stereo – A stereo microphone placement technique that places two cardioid microphones about 20cm apart and set outward from each other at a 90-degree angle to create a stereo image. Particularly for stereo miking at close ranges. (See also “Near-Coincident Miking.”)
Diode – An electrical component that enables easy electrical current flow in one direction but not the other. In the recording studio, these are commonly found in the vacuum tubes of tube amplifiers.
Direct Box – A small device that to converts an unbalanced, high-impedance speaker or instrument-level output to a balanced, low-impedance mic-level output. Frequently used in the signal path connecting electric instruments “directly” to the mixing console, as opposed to miking them acoustically. Also called “direct injection box” or “DI box.”
Direct Current – (abbreviated “DC“) Electrical current that flows in a single direction, as opposed to Alternating Current (AC), which flows in alternating directions. Many electronic devices run on DC, which is usually provided by battery power, USB power or an AC adapter plugged into the wall.
Direct Injection– (abbreviated “DI”) The process of sending an electrical audio signal directly from an instrument to the mixing console through the use of electric pickups or direct boxes, as opposed to using a microphone.
Direct Out – An output available on some consoles which is fed directly from the preamplifier stage of the input, bypassing the channel strips and faders. This feature is often used to send a “dry” signal to a monitor mix or a recording device.
Direct Sound – The sound that reaches a microphone or a listener’s ear without hitting or bouncing off any obstacles (as opposed to reflected or ambient sound).
Directional Pattern – 1) In microphones, a term meaning the same thing as “Pick Up Pattern,” a description of the area in which a microphone is most sensitive to sounds. 2) In loudspeakers, it is the pattern of dispersion, the area that the sound from a speaker will evenly cover in a listening area.
Distant Miking – The technique of placing a microphone far from the sound source in order to pick up a combination of the direct and reflected sounds.
Dispersion (also Dispersion Angle) – The area that is effectively covered by the sound coming from a loudspeaker; specifically, the imaginary boundaries on either side of the speaker at which the sound level is 6 dB lower than if you were standing directly in front of the speaker. Each speaker has both a horizontal and vertical dispersion angle.
Distortion – Refers to the deforming of a waveform at the output of a device as compared with the input, usually due to overload, creating a distorted or “dirty” signal. While electrical or audio distortion is typically unwanted and avoided, it is frequently used in controlled situations in audio to create certain desirable effects, particularly with electric guitars and amplifiers.
Diversity – 1) In audio settings: the use of two or more antennas in a wireless receiver system to prevent dropouts in the audio from a wireless microphone. 2) In other settings: the embracing of the uniqueness of all individuals.
Dolby – The brand name of a manufacturer of noise reduction systems and other audio systems, to improve performance and fidelity of audio recording, playback, and transmission.
Doppler Effect – The phenomenon in which the human ear perceives a change in the frequency (pitch) of a sound while the sound source is in motion. As the sound source approaches, the sound waves travel a shorter distance to the ear, increasing the frequency of the waves and the pitch of the sound; as the sound source moves away, the sound waves must travel farther and farther, resulting in lower frequencies. A common example of this effect is an approaching emergency vehicle whose siren sounds higher as it approaches and lower after it passes. The Doppler Effect can be utilized in audio settings, for example, in the Leslie speaker in which an electric motor rotates the speakers inside the cabinet, constantly changing the distance between the sound source and the listener (or microphone) and creating its signature warbling vibrato effect.
Double – 1) To record a second performance closely matching the first performance, for the purpose of blending the two tracks. 2) To use a delay line with medium delay to simulate double tracking.
Driver – 1) A transducer in a loudspeaker that converts electrical signals into sound pressure waves. 2) A computer program that controls an attached device or piece of hardware.
Dropout – A brief loss of audio signal on tape, or a brief loss of data in a digital audio file (often due to a dropped sample), that can result in an unwanted dip in audio, a crackle or a pop.
Drum Machine – An electronic device containing synthesized and/or sampled drum sounds in its memory, along with an internal sequencer that can be programmed to play drum patterns or loops.
Drum Pattern – A specific sequence of drum sounds played by a drummer or sequenced into a drum machine for use in a song.
Dry – Describes a sound that has no reverberation or ambience, or an audio without any signal processing, as opposed to “wet.” In mixing, many engineers prefer a blend of wet and dry versions of a signal. (See also “Wet.”)
DSP – see “Digital Signal Processing.”
Dub (or Dubbing) – 1) To copy a recording. 2) To record in real time with another recording with the intent of mixing the two recordings (see also “Overdub/Overdubbing”). 3) “Dub” is an abbreviation for “dubstep,” a style or subgenre of electronic music.
Ducking – A compression-based audio effect in which an audio signal is reduced proportionately by the presence of another audio signal, sometimes accomplished through a “sidechain” connection with the signal processor. A notable example is a spoken-word voice-over track recorded over a musical track, where the music drops in volume when the speaker begins to speak. A more subtle example is when an audio engineer “ducks” specific sounds to make room for others in the track; for example, when a bass guitar signal triggers a slight reduction in the level of drums or guitars. (See also “Sidechain.”)
Dynamic Microphone – (Also called Moving Coil Microphone) A microphone in which sound pressure waves are converted to an electrical audio signal by an induction coil moving within a magnetic field—a process often compared to a loudspeaker working in reverse. Dynamic microphones are less sensitive than condenser microphones, but can be effective for miking louder sound sources or for close-miking applications.
Dynamic Processing/Dynamic Signal Processing – The process of automatically changing the level (or gain) to alter the level relationship of the loudest audio to the softest audio. Dynamic processors include compressors, limiters, expanders and gates.
Dynamic Range – 1) The ratio (in dB) between the loudest peak and the softest level of a song or recording. 2) The ratio (in dB) between the softest and loudest possible levels a device or system can provide without distortion.