Microphone Terminology: D (With Definitions)

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Dead:

What does dead mean in reference to a microphone? The term “dead” may refer to three things in reference to microphones. First, “acoustically” dead means there are no reflections or ambient noise in an acoustic space. Second, a “dead mic” is a mic that has stopped functioning. Third, a “dead mic” is a mic with a poor high-end frequency response.


Dead Cat:

What is a microphone dead cat? A microphone dead cat is an additional wind protection layer for microphones or mic blimps/zeppelins. Dead cats are furry (like a dead cat) and are especially useful when recording audio outdoors.

For more information on dead cats, check out my article “What Are Dead Cats And Why Are Outdoor Microphones Furry?

To learn about my recommended dead cats, check out my article Best Microphone Windscreens.


Decca Tree:

Also known as the ABC stereo miking technique

What is the Decca Tree miking technique? The Decca Tree is a stereo miking technique developed by Decca Studios. The Decca Tree has three omnidirectional mics positioned in an upside-down “T.” The left and right mics are spaced 2 m (6 ft.) apart and panned hard left and right, respectively. The centre panned mic is positioned 1 m forward.


Decibel (dB):

What is a decibel and why are decibels important to microphones? A decibel (dB) is a unit used to measure the intensity of sound waves of the power level of an electrical signal (mic signal) by comparing it to a given level on a logarithmic scale. Decibels are dimensionless and are always in reference to a known level.

Common decibel measurements include:


Decibels A-weighted (dBA):

What are decibels A-weighted and how do they apply to microphones? Decibels A-weighted (dBA) express sound pressure level relative to the A-weighted scale. The A-weighted scale is based on the non-linear responsiveness of the human ear to loudness and is in reference to a loudness level of 40 phons. Mic self-noise is often measured in dBA.


Decibels Full Scale (dBFS):

What are decibels full scale and how do they apply to microphones? Decibels full scale (dBFS) express the full scale of digital audio. 0 dBFS is the maximum level a D/A converter is capable of converting to an analog mic signal (AC voltage) and is digitally made of all 1’s. Going above 0 dBFS in a DAW causes digital clipping of a signal, (including mic signals).


Decibels Relative To 1 Volt (dBV):

What are decibels relative to 1 volt and how do they apply to microphones? Decibels relative to 1 volt (dBV) express a mic signal’s voltage relative to 1.0 volts (RMS) at any impedance. dBV values are often given for mic sensitivity ratings. Mic level signals (from microphone outputs) are typically in the region of -60 dBV to -40 dBV.


Decibels Relative To 0.775 Volts (dBu):

What are decibels relative to 0.775 volt and how do they apply to microphones? Decibels relative to 0.775 volts (dBu) express a mic signal’s voltage relative to 0.775 volts (RMS). dBu is derived from the power standard of 0 dBm being equal to 1 mW into a 600Ω load. +4 dBu is the standard professional reference level equal to 0 VU for a 1000 Hz tone.


Decibels Sound Pressure Level (dB SPL):

What are decibels sound pressure level and how do they apply to microphones? Decibels sound pressure level (dB SPL) expresses the intensity of sound pressure relative to the agreed-upon threshold of human hearing. dB SPL units are commonly used in max SPL ratings and in testing the sensitivity of microphones.


Delay:

What is delay and how does it affect microphones? Delay refers to the time difference between two occurrences (ie: a sound wave hitting the front and back of a mic diaphragm; two sound sources reaching a mic; or a sound wave traveling from a source to a mic). It could also mean the latency in a mic signal or refer to a time-based mixing effect.


Desktop Stand:

What is a desktop mic stand? A desktop mic stand, as the name suggests, is a mic stand that sits on your desk and holds a microphone in place. Desktop stands are very useful for cramped workspaces. Desktop stands are often short with circular bases and no arms, though desktop boom arms are also sometimes called desktop stands.


Destructive Interference:

What is destructive interference and how does it apply to microphones? Destructive interference is canceling of out-of-phase sound waves or mic signals. Destructive interference is responsible for bass frequency drop-outs in acoustic space and for the common-mode rejection of EMI in balanced audio.


Detailed:

What is a detailed microphone? A detailed mic captures sound accurately and naturally. Detailed mics generally have flat and extended frequency responses as well as fast transient responses and low self-noise. directional mics are the most detailed on-axis and omnidirectional mics are often more detailed than directional mics.


Diaphragm:

What is a microphone diaphragm? A microphone diaphragm is the thin, movable part of the mic capsule that moves sympathetically with the sound waves around the mic. Diaphragm movement is caused by sound pressure differences between the front and back of the diaphragm and begins the transduction in most mic designs.

For more information on microphone diaphragms, check the following My New Microphone articles:

What Is A Microphone Diaphragm?
What Are Microphone Diaphragms Made Of? (All Diaphragm Types).
Why Are Condenser Microphone Diaphragms Gold-Sputtered?


Differential Amplifier:

What is a differential amplifier and why are differential amplifiers important to microphones? A differential amplifier sums the difference between two input voltages while effectively canceling out any common voltages between the two inputs. Differential amps are crucial for common-mode rejection in mic preamps designed to accept balanced audio from microphones.


Differential Microphone:

Also known as the double carbon microphone.

What is a differential microphone? A differential microphone, developed by Western Electric, is an improvement on the antiquated carbon mic design that had two carbon-filled button capsules instead of one. Two containers kept granules from moving around, yielding lower noise and distortion along with improved frequency response.

See: Microphone.


Differential Signal:

What is a differential signal and how do differential signals apply to microphones? A differential signal utilizes two conductive wires to pass the same audio signal with one of the wires carrying the signal in reverse polarity. Differential signals are outputted from mics and travel through balanced audio lines before getting summed together by a preamp’s differential amplifier.


Diffuse-Field Microphone:

Also known as the random incidence microphone.

What is a diffuse-field microphone? A diffuse-field microphone is a type of measurement mic designed to respond in a uniform manner to sound arriving at its diaphragm from all angles. Diffuse-field mics work best in diffuse sound fields such as reverberation chambers or where several sound sources affect sound pressure at the mic.

See: Microphone.


Digital:

What does digital mean and how does it apply to microphones? Digital audio refers to the digital representation of sound in bit depth and sample rates (1s and 0s). Microphones convert sound energy to analog mic signals which then must be converted via an analog-digital converter for use in digital mixing consoles or DAWs.


Digital Audio Workstation:

What is a digital audio workstation? A digital audio workstation (DAW) is an electronic device or computer software that acts as an audio console for the mixing, editing, and production of digital audio. Mic signals and other analog signals must be converted by an analog-digital converter before use in a DAW.


Digital-Analog (D/A) Converter:

What is a digital-analog converter? A digital-analog converter (DAC) converts digital audio to analog audio. DAC converters are required for digital audio outputs that send audio to analog monitors or loudspeakers.


Digital Distortion:

What is digital distortion and how does it affect microphones? Digital distortion is the changing of a digital audio waveform due to overloading the digital bit depth (clipping at a bit depth made up of all 1’s). Digital distortion can happen in digital mics but most often happens in DAWs when pushing a channel past 0 dBFS.


Digital Microphone:

What is a digital microphone? A digital microphone is defined by having a digital audio output. Digital mics are designed with internal analog-digital converters that convert the mic signal from the capsule to digital information before the mic’s output. USB mics are by far the most common digital mics.

See: Microphone.

To learn more about digital microphones, check out my article Are Microphones Analog Or Digital Devices? (Mic Output Designs).


DIN Pair:

What is the DIN pair microphone technique? DIN pair is a near-coincident pair stereo miking technique. It consists of a pair of cardioid microphones spaced 20 cm (7.9 in) apart, angled at 90° from one another (45° from the “front axis”), and pointing outward.


Direct Current (DC):

What is direct current and what is its role in microphones? Direct current (DC) is the unidirectional flow of electric charge. Although mic signals are alternating current (AC), DC plays a vital role in powering active microphones via phantom power or DC-bias voltage.


Direct Sound:

Also known as incident sound or incident wave.

What is direct sound and why is it important to microphones? Direct sound is the sound produced by a sound source (a vocalist, musical instrument, etc.) that travels through a medium (air) directly to a listener or mic. Direct sound represents a true sound of the source and is different from initial reflections and reverberation, which represents the space.


Directional Microphone:

What is a directional microphone? A directional microphone is more sensitive in some directions than others. Polar patterns identify where directional mics are most sensitive (on-axis) and least sensitive (at the null points). Understanding the directionality of a mic leads to better mic positioning and results.

See: Microphone.


Directionality:

What is microphone directionality? Microphone directionality refers to the differences in mic pick up between the on-axis and off-axis sounds. Unidirectional polar patterns are most sensitive in the on-axis direction. bidirectional mics are most sensitive on-axis and at 180°. Omnidirectional mics are equally sensitive in all directions.


Distortion:

What is distortion and how does it apply to microphones? Distortion is the alteration of a waveform. Analog microphone distortion happens when the circuitry is overloaded. Distortion can also happen digitally inside a DAW when an audio signal exceeds 0 dBFS. Distortion is often unwanted but can be put to good effect.


Diversity:

Also known as antenna diversity or spatial diversity.

What is diversity in terms of wireless microphones? Antenna diversity refers to any of the schemes that utilize two or more antennae to improve the reliability of a wireless connection. By having multiple antennae to choose from, a wireless mic receiver will almost always have a strong wireless connection with few drop-out and little interference.


Double Mid-Side Array:

What is the double mid-side array? The double mid-side array is a surround sound miking technique with two cardioid mics and one bidirectional mic positioned coincidentally. One cardioid points to the front and the other points to the back. The bidirectional mic is placed with negative polarity at 90° and positive polarity at 270°.


Double ORTF Array:

What is the double ORTF array? The double ORTF array is a surround sound miking technique for ambient recordings. It is basically two back-to-back ORTF arrays spaced some distance from one another. This means there are 4 cardioid mics in a rectangular formation pointing outward. The double ORTF is very similar to the IRT Cross.

Double ORTF Drawing

Double Spiral Shield:

Also known as the Reussen shield.

What is a double spiral shield and why are double spiral shield important to microphones? A double spiral shield is a type of cable shield that features two overlapped shield layers that are wound in opposite directions and at 90° to one another. Double spiral shields are flexible and provide excellent EMI protection, which is what we want in a microphone cable.


Dropout:

What is a microphone dropout? A microphone dropout happens when there is a drop in connectivity between a wireless mic’s transmitter and receiver. Using proper wireless radio frequencies and receivers with true diversity helps to reduce unwanted dropouts in wireless mic signals.


Drum Booth:

What is a drum booth? A drum booth is a room in a recording environment that is used for isolating and recording drums. Professional drum booths range from small acoustically dead iso-booths to specially designed drum rooms with characteristic sounds. Drum booths provide isolation and flexibility with mic placement.


Dynamic Microphone:

What is a dynamic microphone? A dynamic microphone is a transducer that utilizes electromagnetic induction to convert sound energy into electrical energy. A conductive element (voice coil or ribbon) either acts as a diaphragm or is attached to a diaphragm and vibrates in a magnetic field to produce a coinciding mic signal.

See: Microphone.


Dynamic Range:

What is dynamic range and why is it important to microphones? A mic’s dynamic range is the range between the weakest sound pressure level (SPL) and the strongest SPL that mic can reproduce accurately. The dynamic range of a condenser mic is the mic’s maximum SPL rating minus its self-noise rating. Dynamic mics often have dynamic ranges too wide to consider.


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