Файл: Sound Tech Terms Dictionary.pdf

G

G722:  An international telecommunications standard for data reduction used for limited-

bandwidth speech over digital telephone networks; used only in basic ISDN applications.

gaffer:  (1) On a film set, the head electrician, now more commonly called the “Chief Lighting

Technician.”  (2) In film, the head of a crew, e.g., the “gaffing mixer” would be the re-
recording mixer-in-charge, formerly known as the gunner.

gain:  The output voltage of a device divided by its input voltage.  Most passive devices have

a negative voltage gain, and most active devices, especially amplifiers, have a positive voltage
gain.  Usually expressed in dB, this is correct only if the input and output impedances are the
same, a condition not usually met.  The square of a voltage ratio is a power ratio if the
condition of matched impedances is met.  See amplifier gain, impedance-matching.

gain-before-threshold:  In a compressor or limiter, the decibel gain applied to signals below

the threshold level, i.e., before the compression circuit.

gain control:  The fader that controls the strength of the output signal of an amplifier.  This

term is misused on many amplifiers, since the gain remains constant, while the gain control
actually adjusts the signal input level.  Also erroneously called volume control on consumer
equipment.

gain riding:  Manual, real-time volume control during recording to prevent overload and dis-

tortion at loud levels, and to avoid noise problems at low levels.

gain stages:  Electronic components (or sets of components) whose purpose is to provide sig-

nal amplification in an active device.

gallows arm:  A type of mic stand which consists of a vertical section, to the top of which is

fitted an adjustable rod which carries the microphone.

galvanic isolation:  In transformer, galvanic isolation means that no electrical current can

flow directly from one winding to the other as they have no direct electrical contact.  How-
ever, a signal can flow between the windings via electromagnetic coupling.

gang:  To mechanically or electrically couple two or more controls, such as post-effects proc-

essors, faders, etc.  The combined assembly is then called a ganged fader, etc.  See grouping.

gap:  The distance between the pole pieces of a magnetic tape head.  The gap width is the di-

mension of head gap measured along the tape path, typically 90 mils for a professional play-
back head, 150 mils for a record head, and 400 mils for an erase head.  Sometimes specified in
microns.

gap scatter:  Any deviation from perfect head gap-track alignment on a multitrack tape re-

cording.

gap width:  See gap.

gate:  (1) See noise gate.  (2) A control voltage generated by any key on a synthesizer keyboard

that instructs signal generators and other devices to begin operating.  (3) The part of a movie
camera that has an opening to allow light from the lens to expose the film, and that holds the
film steady during that exposure.  In a projector, the light source illuminates the frame held
steady in the gate.  The lens then projects the image onto a screen.

G

gated reverb:  The use of a noise gate to cause a sudden termination of a reverberation effect,

without allowing the normal decay segment to complete.  This gives the sound an unnatural,
industrial timbre.

Amplitude

Time

Initial

Delay

| |

Gated Reverb from a Percussive Sound

Gated sound is created by abruptly
terminating reverberation decay

Impulse,

such as a

hand-clap

gauge:  The width of a particular film stock, e.g., 8mm, 16mm, 35mm, 65mm, or 70mm.  See

format.

gauss:  (1) The unit of magnetic field strength, reflecting maximum flux density.  (2) The unit

of measurement for remanent magnetization on recording tape.

General MIDI (GM):  A subset of the MIDI specification which is a minimum set of require-

ments for MIDI devices aimed at ensuring consistent playback performance on all instru-
ments bearing the GM logo.  Some of the requirements include 24-voice polyphony, a stan-
dardized group (and location) of 128 sounds, that the synthesizer be 16-part multitimbral, and
provides for a standard pitch encoding.  Some manufacturers have proposed supersets to
GM, e.g., Roland’s GS and Yamaha’s XG.

generation:  A term for the number of successive times a sound has been copied on analog

magnetic tape.  The original recording is the first generation, a copy from that is a second
generation, etc.  Thought to be less relevant in digital recording, but that’s thoughtless.

generator module:  A synthesizer module that generates sound, usually through an oscillator.

ghost:  The slight pre-echo heard on a record one revolution before the beginning of a loud

band, or just after the loud band stops.  The waveform carved by the cutting stylus in the
modulated groove deforms the adjacent blank groove, resulting in a faint repeat of whatever
the modulated groove contains.  Analogous to print-through on magnetic recording tape.

gink:  In film, to screw up.

G

glass master:  A glass disc with a light-sensitive coating, whose surface can be etched with

pits by a laser beam as modulated by an audio signal.  This surface is then sealed with a
coating of silver.  Used as a master for the dies from which CDs are eventually pressed.  The
laser device that burns the pits in the coating on the glass surface of a CD is called a glass mas-
ter lathe.

glide:  A function, also called portamento, in which the pitch moves continuously from one

note to the next, such as is possible on a violin or trombone, instead of jumping over the in-
tervening pitches, such as is necessary on a keyboard instrument or woodwind.

glissando:  A direction for piano or harp by sliding the fingers over the keys or strings.  Only

the C

maj

 and pentatonic scales can thus be played (on the white and black keys, respectively).

Compare with arpeggio, portamento.

global:  Pertaining to or governing all of the operations of a digital synthesizer, module, or

other instrument.

GM:  See General MIDI.

gnat’s nut:  See RCH.

gobo:  Any kind of moveable sound-absorbing surface or panel used in recording sessions to

acoustically separate sound sources.  See baffle.

grabbing:  The process of importing digital audio from an audio CD directly onto a com-

puter’s hard disk.  Also called, by the verbose, digital audio extraction.

grain:  (1) A subtle type of distortion found in some audio devices, mostly digital devices but

sometimes also power amplifiers, possibly due to crossover distortion.  (2) The ferrous particles
on a tape which determine the amount of distortion caused by the Barkhausen effect.  Digital
media have grain only if the reconstruction filters are badly designed.  See granulation.

granular synthesis:  A sophisticated form of additive synthesis, combining sound elements

called grains, which have a specific duration (typically 1-50ms), waveform, peak amplitude,
and bell-curve amplitude envelopes.  Hundreds or thousands of grains are combined per
second to form an event.  An event has such attributes as start time, duration, initial wave-
form, waveform slope, initial center frequency, frequency slope, bandwidth, bandwidth
slope, initial grain density (number of grains per second), slope, initial amplitude, and ampli-
tude slope.  Essentially, a sound event is sliced into time screens that contain the amplitude
and frequency dimensions of hundreds of events.  These screens are assembled into books that
define a complete sound object.

granulation:  An aliasing type of distortion in digital audio systems due to the uncertainty in

the level of the samples is known as granulation, also called quantization distortion.  If the
sampling rate is an exact multiple of the input tone frequency, granulation results in harmonic
distortion, i.e., the distortion components are at multiples of the input frequency.  If not, the
granulation resembles random noise, in which case it may properly be called quantization
noise.  See modulation noise.

graphic editing:  A method of editing parameter values using graphic representation (for ex-

ample, of envelope shapes) displayed on a computer screen.

G

graphic equalizer:  A graphic equalizer can be recognized by the row of faders across the

front panel, each fader controlling its own narrow section of the audio spectrum.  Other than
the highest and lowest faders, which control shelving filters, each of the filters in a graphic
equalizer is a fixed-frequency bandpass filter, where the range of each fader is fixed, and the
width of each individual band of a third-octave equalizer is actually wider than a third-
octave.  See equalizer, parametric equalizer.

ground:  Refers to a point of, usually, 0V, and can pertain to a power circuit or a signal cir-

cuit.

ground lift/lifter:  The practice of or a device for disconnecting the shield on one end of a bal-

anced cable to eliminate a ground loop.  Sometimes in the form of a switch found on some
audio adapter boxes or DI boxes, this switch or cable modification disconnects the chassis
ground of a device.

ground loop:  The situation which arises when two pieces of equipment, each having an es-

tablished chassis ground internally connected to signal ground, are then connected via a
shielded cable.  This forms a relatively large loop from chassis ground to signal ground
(shield), shield ground to signal ground, and chassis ground back to chassis ground.  Because
the electrical pathway formed in this manner has a finite impedance, a difference in potential
may occur from one end of the loop to the other, allowing an AC-frequency signal to form in
the circuit.  This signal will manifest itself as a hum which can, in extreme cases, be louder
than the audio signal.  The solution is to break the screen connection between the two de-
vices, ideally at the end of the cable that is plugged into a receiver, such as a mixer or ampli-
fier with a ground lifter.

group delay:  The rate of change of phase of the response of a device or a system as a function

of frequency.  A pure time delay, equal at all frequencies, gives a constant slope of phase ver-
sus frequency.  If, in an audio component (frequently a passive network), this slope is not con-
stant but varies with frequency, the component is said to produce group delay distortion.  This
is equivalent to a time delay that varies with frequency, called a group delay because the dis-
tortion occurs within a group of adjacent frequencies, but not over the entire spectrum.  The
audible result is a loss of precision in musical transients; they are spread out or smeared in
time and a more diffuse stereo image results.

group fader:  A control which sums and adjusts the output of several other faders which

have been routed to that group.  See gang, grouping.

grouping:  A feature of some sequencing programs or mixers which allows for the assign-

ment of several faders to a group master fader that controls the overall level for the group.  The
software analog of a hardware gang.

group master:  See submaster.

grunge:  See mid-range smear.

guard band:  A narrow, unrecorded area between the recorded tracks of a magnetic tape in

order to reduce crosstalk between the channels of the tape recorder, resulting in each track of
the tape using slightly less than     

1

n

tracks-width of the tape.

guide vocal:  In multitrack recording, a preparatory vocal track to serve as a template for the

later recording of instrumental tracks, eventually replaced by a final version.