Файл: Sound Tech Terms Dictionary.pdf

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compression driver:  A specialized mid- or high-frequency speaker consisting of a small dia-
phragm and voice coil coupled to a large magnet structure.  The unit is mounted to a horn
which acoustically matches the impedance of the driver to the impedance of the air and
shapes the signal.  Expensive due to the precise tolerances required, compression drivers are
substantially more efficient than traditional direct-radiating cone speakers.

compression ratio:  (1) The ratio of the dB change from input level to output level effected
by a compressor, once the threshold has been exceeded.  (2) In data compression, the ratio of
the number of bytes of uncompressed to compressed data, an indication of the space-saving
efficiency of the compression algorithm.

compressor/limiter:  A device for reducing the effective dynamic range of an input signal by
preventing it from rapidly exceeding or falling below a selected amplitude threshold.  The
first part of a compander, it is used to make loud parts of a signal softer and soft parts louder.
Beyond the threshold, the ratio of the signal’s input level to its output level (e.g., 2:1, 4:1) is
user-selectable.  A compressor is commonly used to keep mic levels within an acceptable
range, but because it can slow a signal’s rate of decay below the threshold, compressors are
also used to add sustain to instruments such as electric guitar and bass.  The limiter acts like
a compressor, but operates only at the top end of the dynamic range.  The limiter has a faster
attack time (1µs to 1ms) than the compressor alone (1ms to 10ms).  A compressor/limiter is
inserted between the outputs of a MIDI soundcard, synthesizer, or mixer and the inputs of
the mixdown deck.  See hard knee compression, soft knee compression.

Comtek:  (1) A Salt Lake City-based company that makes portable wireless transmitters and
receivers.  (2) The generic name for wireless headphone feeds to directors and for wireless
timecode feeds to slates.

concert pitch:  Established by ISO in 1955, the agreed reference frequency of 440Hz, for the
note A above middle-C, notated A=440.

condenser microphone:  A condenser, or capacitor, mic capsule has a conductive diaphragm
and a metal backplate placed very close to the diaphragm.  They are charged with static
electricity to form two plates of a capacitor.  When sound waves strike the diaphragm, it vi-
brates, varying the spacing between the plates.  In turn, this varies the capacitance and
makes a signal analogous to the incoming sound waves.  There are two types of condenser
mics:  the true condenser and the electret condenser.  In the former, the diaphragm and back-
plate are charged with a voltage from a circuit.  In the latter, the diaphragm and backplate
are charged by an electret material, which is in the diaphragm or on the backplate.  All true
condenser mics need a power supply to operate, such as a battery or phantom power.  In gen-
eral, condensers have a smooth, detailed sound with a wide, flat frequency response--usually
up to 15kHz-20kHz, useful for cymbals or instruments that need a detailed sound, such as
acoustic guitar, strings, piano, or voice.  Condenser mics tend to be more expensive and
fragile than dynamic microphones.  Note that omnidirectional condenser mics have deeper
lows than cardioid condensers, making the former a good choice for pipe organs and bass
drum.  See also boundary microphone.

conductance:  The reciprocal of resistance, or electric current divided by voltage.  The tradi-
tional unit of conductance is the mho (ohm spelled backwards).  See also impedance.

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conductivity:  A material which exhibits efficient thermal or electrical transference through
itself is said to have a high conductivity.  Conductivity in a material is rated as its resistivity,
the inverse of conductivity, in ohms per meter.  Metals have a high conductivity owing to the
large number of free electrons in metal atoms which efficiently transfer the current or heat
from one part of the material to another.  An insulator, on the other hand, is a material with
few free electrons, and hence does not readily pass heat or current.

cone:  The vibrating diaphragm of a dynamic or moving coil loudspeaker, usually made of pa-
per and shaped roughly like a cone.

conform:  (1) To re-edit sound stems to match a new version of the picture edit, which is the

final matching of all music, dialog and/or special effects to the video image.  This may in-
volve synchronization, editing, and re-recording one or more of the components of the final
sound/video mix. (2) To assemble sound elements from their original sources to match their
location in a picture edit, often with the assistance of an EDL.

console:  See mixer.

consonant:  Literally “sounding together.”  Musical tones that are consonant sound harmo-
nious or in tune when sounded together rather than discordant or harsh.  Musical intervals
composed of tones that have relatively simple frequency ratios are more consonant than
ones with more complex ratios.  The most consonant interval is considered to be the octave,
which has a frequency ratio of 2:1.

contact:  See wrap.

contact enhancer:  A chemical compound which, when applied to plugs, sockets, or other
metallic electrical connection, improves the electrical conductivity between the metal sur-
faces, making a better, less noisy contact.

contact microphone:  A mic that is physically attached to the body of an instrument or other
sound source.  It is primarily the vibration of the contact microphone’s body itself that is the
transducer.  By comparison, other microphones contain an internal diaphragm or membrane
that vibrates in response to sound carried to it through the air, while the capsule of the mi-
crophone itself remains motionless.  See also bug, piezo pick-up.

container:  Film sound slang for Dolby Laboratories’ peak limiter designed specifically for
controlling the dynamics of program material during SVA printmastering.

Continue:  A MIDI Real-Time system message, correctly written Song Continue.

continuous controller:  A type of MIDI channel message that allows dynamic, real-time control
changes to be made in notes that are currently sounding.  There are 128 possible continuous
controllers on each of 16 MIDI channels, and each of these controller types can have any data
value between 0 and 127.  Modulation (such as pan or volume) is an example of a true MIDI
continuous controller.  Continuous controller 1 is always the modulation wheel; controller 7
is the instrument’s main volume.  See controller.

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continuous sync:  A software feature where the DAW will create a new clock based on in-
coming SMPTE timecode to enable recording to the DAW from an ATR.  The result is that the
sample rate of the DAW will vary continuously, effectively speeding up and slowing down
to track the timecode variations.  Continuous sync requires dedicated hardware, and may
not be available on all DAWS.  For example, ProTools™ has a feature for continuous sync
which is necessary when syncing continuously to an ATR while recording on any digital
machine as the SMPTE timecode-based clock is not guaranteed to be at the precise sampling
rate.  The ProTools Slave Driver™ does the sample rate conversion in the ProTools hardware
so that the audio quality of the digital data isn’t compromised.

contour generator:  See envelope generator.

Control and Display signals (C&D):  Also called PQ codes.  In the CD  format, eight addi-
tional bits are added to each frame of audio data; this means that a byte of information is
available from the disc every 136 µs.  Each bit in the added byte is given a one-letter name,
P-W.  Thus, eight separate subcodes can be recorded on and recovered from the CD.  So far
only P and Q are used:  the P-code is used for the pause signal between musical tracks and at
the end of the last track, and the Q-code tells the player if the recording is two- or four-
channel (no quadraphonic CD player is yet available).  The Q-code also contains timing in-
formation about the tracks and identifies the country of origin and date of the recording.  No
standard has been defined for the use of the other six subcodes.

control module:  The part of a synthesizer that tells the sound generators and controllers

what to do to make a given note.  These modules include envelope generators, LFOs, the key-
board itself, and the modulation and pitch-bend wheels.  These allow control of some aspects
of a synthesizer’s sound by sending signals to the sound generators and modifiers telling
them now to behave.  For instance, the keyboard sends a signal to the oscillator telling it
what frequency to play.  Also called modulation modules.

control panel:  A file which becomes a part of the Mac’s system software, giving the user
either control over or adding functionality to various aspects of the operating system, pe-
ripherals, or applications.  See also extension.

control track:  (1) One track of a multitrack magnetic tape recorder used for recording spe-
cial signals that provide control information to the recording console during automated
mixdown.  (2) A dedicated track prerecorded with a pilot tone, used on video tape which
marks the start of each video frame in order to resolve playback speed by controlling and
synchronizing the video frames.  Can be used to count time for editing, but is prone to slip
and lose count during winding.  In 1” and 

3

4

” formats, SMPTE timecode information is sent

to a separate address track which creates confusion about the names of both of the tracks.  See
blacking, sync-lock.

control voltage:  A voltage, usually varying, used in synthesizers to control various pa-
rameters of the signal being produced.  Control voltages are used for envelope control, pitch
control, and filter bandpass and rolloff frequency control, etc.  Suitable control voltages can be
generated in various ways, one of the most straightforward of which is by a standard key-
board.  See VCA, VCF, VCO.

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controller:  (1) Any device, for example, a keyboard, wind synth controller, or pitch-bend
lever, capable of modulating a sound by altering the action of some other device.  (2) Any of
the defined MIDI data types used for controlling the on-going quality of a sustaining tone
via a controller message.  In many synthesizers, the controller data category is more loosely
defined to include pitch-bend and aftertouch data.  See continuous controller.

controller change:  A Channel Voice message which allows for musical effects such as vi-
brato or sustain on currently active voices.

controller chasing:  A sequencer feature whereby whenever playback is requested, the se-
quencer looks back for the most recent controller, pitch-bend, aftertouch, and similar parame-
ters and sets everything accordingly so that playback started in the middle of a song replays
correctly.

convolution:  (1) In any linear system or device, the output signal is a function of the input
signal and the characteristics of the device.  The interaction between the input and the device
is described by a mathematical infinite integral called convolution.  The output is the input
convolved with the impulse response of the device.  The spectrum of the output of a device is
simply the spectrum of the input multiplied by the frequency response of the device via the
FFT.  (2) The modulation of one audio file by another.  For example, the use of a hand-clap
echo sample could be convolved with a guitar chord sample to produce an echo effect which
sounds like it was produced by the guitar.

copy editing:  The process of re-recording or copying selected extracts from original sound

or video recordings and rearranging their order as they are copied, so that the copy will
have all the desired segments in the correct order.  This copy is called an assembly, and will
generally need fine editing in order to meet timing or other production requirements.

corner frequency:  See rolloff frequency.

correlated noise:  See distortion.

cosine microphone:  See figure-eight microphone.

cottage loaf microphone:  See supercardioid or hypercardioid microphone.  UK usage.

coulomb:  The coulomb is the unit of electric charge (C), and is the quantity of electricity
transferred in one second by a current of one ampere.

counts:  A slang term for footage numbers or cues for specific events in a film or videotape.

Also called footage counts.  See feet/frames.

coupling:  The process of or means by which energy is transferred from one system or me-
dium to another.  For example, the coupling of acoustic energy from a loudspeaker to the
surrounding air.

cps:  (1) centimeters per second.  The speed of movement of tape past a tape read/record

head, also denominated in ips, inches per second.  (2) cycles per second, or Hertz.

C.R.:  Con Repeats.  As in, “Play from the beginning with repeats” is written, “D.C. (C.R.).”

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CRC:  Cyclic Redundancy Check.  A system of recording a checksum number along with data
in order to detect, and in some cases, correct any corruption of the data.  See ECC.

crescendo:  A gradual increase in loudness of a musical sound.

crest factor:  The ratio between the average amplitude as shown on a VU meter and the in-

stantaneous amplitude as shown on a peak meter.  The human ear is very sensitive to this dif-
ference.

critical distance:  The distance from a loudspeaker where the direct sound is equal in inten-
sity to the reverberant sound.  See also free-field.

critical frequency:  See rolloff frequency.

crossed pairs:  See coincident pair.

cross-fade:  A velocity threshold effect in a synthesizer in which one sound is triggered at low
velocities and another at high velocities, with a fade-out/fade-in transition between the two.
If the transition is abrupt rather than gradual, the effect is called cross-switching rather than
cross-fading.  Cross-fading can also be initiated from a footswitch, LFO, or some other con-
troller.

cross-fade looping:  A sample-editing feature found in many samplers and most sample-
editing software, in which some portion of the data at the beginning of a loop is mixed with
some portion of the data at the end of the same loop, so as to produce a smoother transition
between the end of the loop and the beginning of the loop replay.

cross-interleaving:  See interleaving.

cross-mod:  Cross-modulation test.  A means of determining correct exposure on a track
negative to result in minimum distortion on a positive print.  Tests are conducted to
determine the relationship of specific optical cameras to specific laboratories.