Glossary of Terms
_____________________________________________________________
35
Ambient noise -
Low-level noise created by environmental factors such as fans, air conditioners,
heaters, wind noise, etc.
Attack time -
Describes the amount of time it takes compressor circuitry to react to and reduce the
gain of incoming signal. A compressor set to a fast attack time kicks in almost immediately and
catches transient signals of very brief duration, reducing their level and thus "softening" the sound. A
slow attack time allows transients to pass through unscathed before compression begins on the rest
of the signal.
Balanced
- Audio cabling that uses two twisted conductors enclosed in a single shield, thus allowing
relatively long cable runs with minimal signal loss and reduced induced noise such as hum.
Class A
- A design technique used in electronic devices such that their active components are
drawing current and working throughout the full signal cycle, thus yielding a more linear response.
This increased linearity results in fewer harmonics generated, hence lower distortion in the output
signal.
Clipping -
A particularly harsh form of audio distortion, caused when the loudness of an incoming
signal exceeds a digital audio recording device’s capability to represent its amplitude. When that
happens, the peaks of the signal simply get “clipped” off, thus drastically changing the waveform
and yielding an especially unpleasant sound.
Compression -
The process of automatically reducing the level of peaks in an audio signal so that
the overall dynamic range—that is, the difference between the loudest sections and the softest
ones—is reduced, or compressed. “Compression” is sometimes described as “gain reduction” or
“peak reduction.”
Compression ratio -
A term that describes the amount of increase required in the incoming signal in
order to cause a 1 dB increase in output. A ratio of 2:1, for example, means that any time there is an
increase of 2 decibels in the loudness of the input signal, there will only be a 1 dB increase in output
signal. When compression ratios of 10:1 or higher are being used, the device is instead said to be
limiting.
Condenser microphone
- A microphone design that utilizes an electrically charged thin conductive
diaphragm stretched close to a metal disk called a backplate. Incoming sound pressure causes the
diaphragm to vibrate, in turn causing the capacitance to vary in a like manner, which causes a
variance in its output voltage. Condenser microphones tend to have excellent transient response but
require an external voltage source, most often in the form of 48 volts of “phantom power.”
DAW
- An acronym for “Digital Audio Workstation”—that is, any device that can record, play back,
edit, and process digital audio.
dB
- Short for “decibel,” a logarithmic unit of measure used to determine, among other things, power
ratios, voltage gain, and sound pressure levels.
dBm
- Short for “decibels as referenced to milliwatt,” dissipated in a standard load of 600 ohms.
1 dBm into 600 ohms results in 0.775 volts RMS.
