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Audio Dynamics Processing Final

Terms in this set (33)

DSP (Digital signal processing)
has look ahead capabilities; offers greater accuracy and reduced cost.
compressor
reduce (compress) the dynamic range of the signal passing through them; they turn down the loudest signals dynamically
threshold
point above which everything will be turned down a certain amount
ratio
defining just how much a "certain amount" is, in dB.
key to understanding compressors
always to think in terms of increasing level changes in dB above the threshold point
Broadband compression
the simplest form of com- pression, where all frequencies are compressed equally and the side-chain is equally sensitive to all frequen- cies.
Side Chain Controls
threshold, ratio, attack, gain, release, knee
Preferred gain range for professional applications
±12 dB with a center-detent 0-dB unity gain position
release time calculation
(Gain Reduction x Release Set- ting) / 10 dB
Typical compressor and expander release settings
25 ms and 2 seconds
gate mode
he release time determines how quickly the gate closes as the control signal drops be- low the threshold setting
expand mode
the release time determines how quickly the signal is turned down as the control signal moves below the set threshold
duck mode
the release time determines how quickly the signal is ramped up when the control signal drops below the threshold setting.
hard knee
does nothing until the signal exceeds the threshold point, and then applies full compression.
soft knee
significantly reduces distor-
tion caused by abrupt transitions from unity gain to
a compressed signal. An accurate soft knee response is difficult to achieve using analog methods.
Frequency sensitive compression
s broadband compression as described above with the addition of side-chain equalization to make the detector more or less sensitive to certain frequencies
Split-band Compression
divides the incoming signal into two or more frequency bands
Dynamic EQ
differs from the forms of compression listed above in that it dynamically controls the boost/ cut of a parametric filter rather than broadband fre- quency gain. The basic dynamic EQ uses a bandpass filter in the side-chain with variable center frequency and bandwidth
Relative Threshold Dynamic EQ
special form of dynamic EQ where the rms level of the bandpass signal in the side-chain is compared to the rms level of the broadband signal
De-essers
limits or controls the sibilant content of speech
Automatic Gain Control (AGC), also known as Au- tomatic Level Control (ALC)
is a specialized form of compression; circuit or algorithm that varies gain as a function of the input signal amplitude. Ex: speech and DJ mixers
Peak Limiter
must ensure that a signal never exceeds the set threshold. This requires the use of a peak responding detector and a fixed ratio of ∞:1
expanders
omplement compressors by increasing (expanding) the dynamic range of the signal passing through it, i.e., an expander is a compressor running in reverse.
A ___ is to an ____, as a ____ is to a ______.
gate, expander, limiter, compressor
gate typically used to
to remove background noise between louder sounds
Good gate
able to look ahead;
Gate: Additional Side Chain controls
hold: determines how long the gate remains open after the control signal drops below the threshold setting. Depth:control determines how many dB the signal is attenuated when the con- trol signal is at or below the threshold setting
look-ahead detector
works by delaying the main audio signal a short amount (a few millionths of a second) while not delaying the side-chain signal. This allows examining the signal in advance to determine the appropriate response before an event
Pre-ramping
allows gating on the main signal as soon as the signal reaches the threshold
ducker
dynamics processor that lowers (ducks) the level of one audio signal based upon the level of a second audio signal or a control trigger. It reduces the level of the main signal by a certain amount (usually labeled Depth) when the side-chain signal exceeds a set threshold. common use: DJ talk over
feedback suppressor
dynamics processor that uses automatic detection to determine acoustic feed- back frequencies and then positions notch filters to cancel the offending frequencies. Other methods use continuous frequency shifting (a very small amount) to prevent frequency build up and feedback before it happens.
leveler
dynamics processor that maintains (levels) the amount of one audio signal based upon the level of a second audio signal
Exciters (or enhancers)
popular special effects signal processing products used in both re- cording and performing. All of them work by adding musical overtones — harmonic distortion really — but hopefully pleasing harmonic distortion
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