Файл: Sound Tech Terms Dictionary.pdf

V

VITC:  Vertical Interval Timecode.  A means of recording SMPTE timecode or other timecode

into the vertical blanking interval on a high-end, pro video recorder, offering the advantage of
being readable even when the tape is not moving.  As the VITC signal is recorded by the ro-
tary heads, it must be recorded at the same time as the video signal, whereas timecode signals
recorded on a VTR’s linear audio tracks can be striped either before or after the video picture is
recorded.

VMAx:  Virtual Multi Axis.  A 3D audio technology developed by the Harman Interactive

Group which purports to deliver ambisonic sound through two channels.  VMAx 3D Interactive
is a version aimed at multimedia computer applications, while VMAx 3D VirtualTheater™ is
the edition of VMAx used for decoding Dolby ProLogic and AC-3 programs for two-channel
playback.  There is also a VMAx Stereo Enhancement for adding width and depth to stereo im-
aging.

V/O:  See voice-over.

VOC (.VOC):  A file extension specifying the Creative Labs’ Sound Blaster™ audio format.

Typically encountered as 

FILENAME.VOC

.  Originally 8-bit, newer cards accommodate 16-bit

stereo sound.  VOC files support compressed or uncompressed data at a range of sampling
rates up to 44.1kHz.  Compression options are from 2:1 to 4:1.  Not as popular as the .WAV
format.

vocal booth:  An acoustically isolated booth in which one or more singers can perform while

rhythm instruments are playing in the studio, but that keeps leakage of these instruments from
reaching the mics located inside the booth.  The same booth can be used to house acoustic in-
struments being played at the same time as amplified ones in the studio, or vice versa.

vocal score:  A notated form of vocal music in which any orchestral parts are expressed as a

piano (treble and bass clef) score, i.e., there is no full score.

vocoder:  Voice Operated reCOrDER.  A signal processor (considered one of a family of analy-

sis synthesizers) that imposes the amplitude envelopes of one input (control) signal upon a sec-
ond input (program) signal.  In the most common application, someone speaks into a micro-
phone to provide a control signal; the amplitude characteristics of the speech elements are su-
perimposed on an input instrument, giving the latter a “talking” quality.  Vocoders use a bank
of bandpass filters to dynamically analyze the frequency spectrum of the control signal and thus
continuously derive the amplitudes of the component frequency bands.  The resulting ampli-
tude envelopes are used to continuously control the operation of another, identically tuned
bank of filters.  Any program signal applied to the input of this second bank will be shaped by
the amplitude envelopes of the control signal, yielding the same spectral characteristics as the
control input.

voice:  (1) The simplest, individual sound-producing circuitry (generator module) an instrument

possesses; an element of synthesizer circuitry capable of producing a note, which typically
consists of the combination of oscillator/filter/amplifier with associated envelopes for the filter
and amplifier.  The polyphonic capability of a synthesizer is defined by now many voices it has.
See voice channel.  (2) In Yamaha synthesizers, a patch.  (3) The instrument for human speech
or singing.

V

voice channel:  A signal path containing, at a minimum, an oscillator and a VCA, and capable of

producing a note.  On a typical synthesizer, two or more voice channels, each with its own
waveform and parameter settings, can be combined to form a single note.

voice coil:  The transducer part of a loudspeaker, consisting of a coil of wire mounted on a

frame.  Variations in the electrical signal passing through the coil cause it to be repulsed from,
or attracted to, a fixed magnet in proportion to the frequency and amplitude of the signal.  The
resulting motion is mechanically transmitted to an attached cone, whose piston effect excites
the surrounding air to reproduce recorded sound.

Voice of the Theater™:  A motion picture theater speaker system developed in the 1940s by

the Altec Lancing Corporation, and the industry standard for forty years until the introduction
of direct radiator speakers.  The Altec Lansing loudspeakers included the single-cabinet A-7 and
A-4, and the dual-cabinet A-2 for larger theaters.

voice-over:  An audio track containing an announcement or narration to accompany a TV or

film advertisement, recorded by a person who does not appear on camera.  Often abbreviated
as V/O.  See also post-sync.

voice stealing:  A process in which a synthesizer that is being required to play more notes

than it has polyphony switches off some currently sounding voices (typically those that have
been sounding the longest or are at the lowest amplitude) in order to assign them to play new
voices.  See dynamic voice allocation.

voiced:  An amplifier which is designed to have a frequency response which is shaped to a par-

ticular instrument, rather than being completely flat.  An example are the loudspeakers sys-
tems used for electric guitars and basses.  The amplification has a very limited frequency re-
sponse which filters out the worst of the distortion due to the amplifier.

voicing:  (1) The process of creating a sound on a piano, organ, or synthesizer; voicing means

much the same thing as programming.  (2) Room equalization.

volt:  Unit of electrical potential between two points in space where V=Resistance 

×

 Current

(V=IR), resistance is in 

Ω

, current in amperes, equal to the force required to produce a current of

one ampere through an element having a resistance of one ohm.  See Ohm’s Law.  The voltage of
an audio signal is usually measured in terms of the RMS value of the signal, but sometimes the
peak or average voltages are measured.  The RMS voltage squared is proportional to the
amount of power the signal carries.  See also VA.

voltage:  The difference in the electrical potential of two points in a circuit.

voltage-controlled amplifier:  See VCA.

voltage controlled attenuator:  An amplifier or resistive network whose gain is unity gain at

maximum, and whose attenuation of an audio signal varies in proportion to an externally
supplied DC voltage.

voltage-controlled filter:  See VCF.

voltage-controlled oscillator:  See VCO.

voltage gain:  See gain.

V

volume:  (1) The degree of loudness or amplitude.  (2) One of the MIDI Controller Change mes-

sages assigned to the parameter in a synthesizer which determines output volume, sometimes
called the Main Volume, although it only operates on the channel to which it is assigned.

volume control:  A voltage divider that adjusts the percentage of input signal without regard

to the input frequency that is applied from one amplifier stage to the next.  Compare with
loudness control, gain control.

volume expander:  A device for increasing the dynamic range and reducing the apparent noise

of a signal.  The second half of a compander.  A volume expander decreases the system gain as
the signal level decreases, making soft signals softer still.  This results in an apparent noise de-
crease because the relative level between the softest and loudest sounds is greater.  If the noise
level is already low enough that the signal will mask it in the loud passages, the expansion will
put the low end of the dynamic range at a point where the ear has reduced sensitivity, making
the noise less audible.

VPM:  Variable Phase Modulation.  A feature of the only modern FM synthesizer, the Korg

Prophesy monosynth and XY polysynth.  Both synthesizers use the carrier and modulator,
and have only two oscillators.  However, these can be set to produce all of the audible wave-
forms.

V.S.:  Volte Subito, meaning “turn the page.”

VTR:  Video Tape Recorder.  A device for recording and replaying video signals on tape, usu-

ally open-reel as opposed to cassette.  See also VCR.

VU:  Volume Unit.  VU meters show how loud various signals are and measure the RMS value

of the input voltage.  For example, a sine wave that alternates between +1V and -1V will pro-
duce a reading on a voltmeter of 0.707V, the average of the voltage in DC.  VU meters may be
the speedometer type or electrical LEDs, and meter scales in dB.  See also crest factor, peak,
PPM.

W

wait:  One of the characters transmitted for the purposes of handshaking in a data transfer.

The character is sent back to the transmitting device by the receiving device to indicate that the
receiver wants the transmitter to pause.

walla:  Background ambient sound added to a film soundtrack to give the affect of an external

environment, e.g., street noise, background conversation.  See also ambience, room tone, NC
Curve.

watt:  A unit of electrical power.  (1) The SI Unit of power: 1 Joule per second.  745.7W=1HP.  (2)

A unit of electrical power, indicating the amount of work deployable into a given load by an
electrical device such as an amplifier or motor.  It is strictly the product of the potential differ-
ence in voltage, (V), current in amperes, (A), and power factor.  In practice, the power factor is of-
ten ignored and the term is reduced to VA.  See output power.

WAV (.WAV):  The Windows audio file format.  Typically encountered as 

FILENAME.WAV

, de-

veloped as the standard format for multimedia sound applications.  WAV is the most common
of several file types that conform to the RIFF specification, and so may be referred to as the
RIFF WAV format.  WAV files can include mono or multichannel audio at 8-bit or 16-bit reso-
lution at a variety of sampling rates up to 44.1kHz.  The format supports different compres-
sion schemes, but the most common is IMA/ADPCM at 4:1 for 16-bit sounds.

WAV/multi-WAV driver:  Used by PC-type system application programs to play sounds on

audio cards.  Unlike the Mac’s Sound Manager, WAV drivers can support multiple channels
(i.e., more than stereo 2-channel), and depending on the hardware, resolutions above 16-bit,
48kHz.

waveform:  The waveform of a signal is a two-dimensional graph of the instantaneous ampli-

tude versus time.  See spectrum.  (1) A signal, either sampled (digitally recorded) or periodic,
being generated by an oscillator.  Each waveform has its own distinctive timbre.  Also called a
sample.  (2) The graphic representation of this signal, as on a computer screen.  See sound syn-
thesis, Appendix C.

waveform modulation:  A voltage-controlled change in the timbre of a note or entire sam-

plepatch, independent of the pitch or frequency normally designated by the keystrokes.  See
sound synthesis, Appendix C.

W

waveform rectification:  A Digidesign™ plug-in that creates new, hitherto-unexplored wave-

forms:

waveform selection:  The waveform selection parameter allows the choice of the shape of the

signal generated by the LFO.  Typical shapes include sine, triangle (tri), square, and sawtooth
(saw).  The two most common waveforms used for vibrato or tremolo are the sine and triangle.
The square wave is used for trills, and saw for special effects.  Some LFOs offer a random (also
called sample-and-hold) waveform, useful for “computer” sounds.  See sound synthesis, Appen-
dix C.

wavelength:  In a sound wave, the distance between two successive pressure maxima is called

the wavelength, and it is equal to the speed of sound divided by the frequency.  See compres-
sion(4), rarefaction.

Frequency

Wavelength

Wavelength

(Hz)

feet/inches

meters/cm

20

50’

16.5m

50

20’

6.6m

100

10’

3.3m

250

4’

1.32m

500

2’

66cm

1,000

1’

33cm

2,000

6”

16.5cm

5,000

2.4”

6.6cm

10,000

1.2”

3.3cm

20,0000

.5”

1.65cm

Unaltered Sine Wave

Positive Rectification (Phase is 100% positive)

Negative Rectification (Phase is 100% negative)

Alternating Rectification

(Alternates between positive and 

negative)

“Alt-Max” Rectification 

(Alternates between holding the peak 

value

of positive and negative wave cycles)

Waveform Rectification