Файл: Sound Tech Terms Dictionary.pdf

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phase-shift:  An alteration of the phase in the partials of a tone.  Virtually all signal processing
devices will cause a certain amount of phase-shift, also called phase modulation, as none of them
are completely phase linear.  Phase-shift is a characteristic of a device and is the change in
phase impressed on a signal that passes through the device.  An electronic device will always
add a time delay to an applied signal.  If the time delay is constant on all frequencies, the
phase-shift between the input and output of the device will be a linear function of frequency,
and the device is called phase linear.  Deviations from phase linearity are called phase-shift.
Equalizers, in particular, exhibit large amounts of phase-shift.  In a complex waveform, phase-
shift will cause a distortion of the waveform, even though the frequency response curve may be
perfectly flat.  There is considerable controversy over whether the ear can detect this type of
phase distortion.  See also PIM.

phase-shifter/phaser:  (1) Phasing is an effect on higher frequencies which make a whispering
or ocean-like sound, produced by a device called a phaser, also called a phase-shifter.  See flang-
ing.  (2) Originally one of the defined MIDI Controller Change messages.  It was assigned to
the parameter in a synthesizer which alters the depth of the effect described as phasing.  More
recently, this message has been reassigned as one of five generalized Effects Depth messages.
See effects control.

phase sync:  In SMPTE timecode synchronization, an option by which the slave machine is
speed-controlled in such a way that the phase of its bi-modulated sync tone is held in phase with
the sync tone on the master machine.  This provides much closer alignment of the two than just
frame lock.  However, because the synchronizer must make continuous adjustments to the
slave’s speed, phase sync can introduce noticeable flutter when the audio machine is slaved to
video.  In some synchronizers, only sub-frame information is used to achieve interlock,
yielding a   1 100 frame accuracy between machines.
phasing:  See phase-shifter/phaser.

phon:  A unit which takes account of the ear’s nonlinear response to the loudness and fre-

quency of a sound.  The phon uses a decibel , i.e., logarithmic, scale which is based on the level
of intensity of a given sound that corresponds to the dB rating of a pure tone at 1kHz, subjec-
tively judged to be of the same loudness.  An increase of one phon is about the smallest incre-
ment in loudness that can normally be perceived.  The scale practically ranges from 0dB to
130dB, and its logarithmic nature means that a rise of three phons approximates a doubling in
intensity.  See equal loudness curves, SPL.

phon lines:  See equal loudness curves.

phone connector:  A   

1

4

” plug connector, called such as it was originally developed by Bell

Telephone.  Used as audio connectors on electric guitars, synthesizers, and some signal proc-
essors and mixers.  See also TRS, TT.

phono connector:  Also called an RCA connector, these are generically known as pin-jack connec-
tors as they contain both the pin and jack portions of a connector.  Commonly used on home
stereo equipment, the phono designation comes from the fact that they are almost universally
used for the outputs on phonographs.

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physical modeling synthesis:  A type of sound synthesis done by programming a computer to
mathematically model the physics of a particular instrument.  These models are sets of com-
plex equations which describe the physical properties of the instrument (such as the shape of
the bell, or type and density of the material) and the way in which a musician interacts with
the instrument, such as plucking, bowing, strumming, blowing, etc.

pick-up:  See DI, piezo pick-up.

Picture Start:  See LFOP, sync pop.

piezo pick-up:  A device, often fitted into the bridges of acoustic guitars, where the mechanical
vibrations in the bridge cause microscopic distortions to the shape of a piezo-electrical crystal,
generating a small voltage in the process.  The other common type of pick-up is the elec-
tromagnetic pick-up used in electric guitars.  EM pick-ups use a coil of wire which senses any
changes in the magnetic field created by a small permanent magnet.  As the guitar string above
the coil vibrates, it disturbs the magnetic field, and the coil generates a small electrical current
which is passed onto an amplifier and loudspeaker.  This is the pick-up part of the DI.

pigtail:  The end of an audio cable which simply has bare wires rather than any type of con-
nector, used to connect cables to binding posts or screw terminals.

pilot:  A 19kHz tone transmitted along with stereo FM broadcasts in order to synchronize the
local oscillator in the receiver to 38kHz for the detection of the stereo subcarrier.  If not filtered
out of the receiver output, it can cause problems with Dolby noise reduction.  See MPX.

pilot tone:  A 60Hz sine wave is recorded on one track of a tape which is used for motion pic-

ture sound recording, generated when the film is being shot, thus the frequency is an accurate
measure of the camera speed.  The pilot is then used later to synchronize the tape playback to
the picture action, allowing movie sound to be recorded independently of the film, as double
system sound.  However, with a pilot tone, although the slave can sync lock with the master, the
slave has no way of knowing where in the program the material the master tape is, and so is
severely limited as a synchronization tool.  The same is true for speed-only sync codes such as
FSK and DIN sync.  See neo-pilot, control track, reference frequency.

PIM:  Phase Intermodulation Distortion.  PIM arises in amplifiers that have a nonlinearity such
that one signal will cause phase modulation of another signal.  Phase modulation is the same as
frequency modulation but to a lesser degree.  For PIM to occur, a high-amplitude signal must
modulate the power bandwidth of the amplifier, and this varying bandwidth varies the phase of
another signal, also being amplified.  See intermodulation distortion.

pin-jack connector:  See phono connector.

pinch wheel:  In a tape recorder, a free-wheeling rubber roller which presses the magnetic
tape against the capstan, ensuring enough friction to drive the tape past the heads.  Also called
a pinch roller.

ping-pong:  (1) A stereo effect generated by an autopanner or some multieffects units,
whereby a sound is made to appear at the extreme right and left of the stereo field in rapid al-
ternation.  (2) See bounce.

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pink noise:  A type of random noise which has a constant amount of energy in each octave band,
as opposed to white noise, which has equal energy at all frequencies.  Pink noise can be made
from white noise by passing it through a filter with a 3dB per octave rolloff.  Pink noise is used
to align the frequency response of tape recorders and loudspeaker systems.

ping-pong:  To bounce tracks in a multitrack recording.

pinning:  Referring to audio level meters, a condition in which the signal is too high, causing
the indicator to hit the top of its scale.  This can damage ballistic meters, such as VU meters, in
addition to producing distortion in the program.

pirate ship:  Film term with means to make a copy of material for one’s own use.  Commonly

used to refer to making a copy of good sound effects recorded in production, thus the order to
“pull up the pirate ship” and to make sure  that those recordings will be available after the film
is finished and masters are sent away.

pitch:  (1) A sound characteristic of repeating vibration at a specific frequency.  Unpitched
sound is called noise.  Pitch is measured in units called Hertz (Hz) which is equivalent to “cy-
cles per second.”  For practical purposes, pitch and frequency are interchangeable terms.  (2)
The number of grooves per inch on the surface of a phonograph record.  (3) The subjective im-
pression of the frequency, or musical tone of a sound, expressed in the latter case by its name-
number, e.g., A2.  Also the frequency of that musical note, e.g., for this example, 440Hz.  (4)
The distance between two perforations or sprocket holes along a strip of film.  Camera-original
film is generally short-pitch, and print film is generally long-pitch, the difference in these
lengths being on the order of .0006” per frame.  The two different pitches are necessary to pre-
vent slippage between original and print film as they wind around various sprocket wheels in
the contact printers used to make most prints.

pitch-bend:  A shift in a note’s pitch, usually in small increments, caused by the movement of
a pitch-bend wheel or lever; also, the MIDI data used to create such a shift.  MIDI Pitch-Bend
messages are a type of MIDI channel message, but not a MIDI continuous controller message.  See
bend.

pitch-shift:  To change the pitch of a sound without changing its duration, as opposed to pitch-
transpose, which changes both.  Some people use the two terms interchangeably.  Also called
time-stretching.  See also frequency shifter.

pitch-to-MIDI-converter:  This translates a monophonic musical line, such as singing or a reed
instrument, into a stream of MIDI data.

pitch tracking:  A misleading term meaning frequency-to-voltage conversion.  A pitch tracker
will accept a complex periodic signal and extract from this the fundamental frequency.  It will
then convert this frequency into a direct voltage output that can be used as a control voltage in a
synthesizer.

pitch-transpose:  See pitch-shift.

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pits:  On a CD, MD, or OD, microscopic depressions laser-burned into the surface on which
the digital data is stored.  Each pit-edge encodes a 1 in the datastream.  Incremental lengths of
flat disc surface (either land between pits or the bottom of an extended pit) designate zeros in
the data.  Audio samples, location and synchronizing information, bands and indexing, visual
information, etc. are all encoded in the pits.

Pit Signal Processing (PSP):  See digital watermark.

pixel:  PIXure ELement.  The smallest visible element of a picture or image, corresponding in
video to the brightness and color information for one location on a single line of the video im-
age.

planar loudspeaker:  A type of dipole loudspeaker design which combines aspects of both dy-
namic and electrostatic designs.  The planar speaker consists of a large plastic sheet with con-
ducting wires imbedded in it, these wires functioning as the voice coil.  Many small magnets in
front and behind the sheet set up a magnetic field so current in the wires causes a force on it
and it moves as a unit, similar to an electrostatic speaker.  Planar speakers suffer from the
same directional problems as electrostatic loudspeakers, but their impedance is more similar to
dynamic designs.

plastic leader:  Usually, white or yellow leader tape in between songs on a master tape.  Plastic
leader can pick up static electricity, which can create clicks or pops on the master tape.  For
that reason, paper leader is generally used on masters.  There are special types of plastic leaders
made of an anti-static base that are used for archival storage where paper leader, which
changes shape in varying humidity and deteriorates with age, will not suffice.  See also leader.

plate:  See back plate.

plate reverb:  An electromechanical substitute for an acoustic reverb chamber, where elec-
tronically generated reverb was unavailable, whereby a metal plate was suspended behind the
sound source, fitted with a transducer and microphone pick-up.  The plate was typically 4’ by
6’, suspended on springs within a sound-deadening case as a reverberant space.  A vibrating
transducer feeds the direct sound into the metal plate, and a pair of pick-ups extract the rever-
beration as vibrations bounce off the plate’s edges.  A motorized damping plate parallel to the
main plate can be remotely positioned at varying distances to control the duration of the re-
verb.  The plate has a characteristic metallic, bright sound.  Other substitutes were spring re-
verbs and slap echo devices.

platter projection:  See projection.

playback:  (1) The amplified reproduction of any type of sound recording.  (2) The reproduc-
tion of a recorded take immediately after it is recorded, done to make æsthetic and technical
judgments about the performance and recording quality.  (3) On a motion picture set, the re-
production of music or other sounds recorded previously under studio conditions, to which
the actors, singers, and dancers in a scene mime and move in exact synchronism.  Called
shooting to playback.

playback-equalization:  See record-equalization.

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playback head:  The head on a tape recorder that is used to detect the varying remanent mag-
netism present on the tape.  The output of this head is then amplified and heard as the re-
corded program.

playlist:  (1) A list giving the chronological order in which a number of pieces of music or

sound effects are to be played.  The list will often describe the start time, duration, and finish
time of each item.  (2) In editing, particularly digital audio editing, a list similar to (1) above
which gives the order in which sections from various recording takes will be used.  It will usu-
ally include timing information which may be locked to timecode, as well as information
about type and duration of crossfades, etc.  Both also known as an EDL.

plosive:  See pop filter.

plug-and-play:  An oft touted feature of PC-type devices, making the promise that the device,
when attached to your system, will simply work as advertised, without making you deal with
arcane hardware or software settings and/or subtle issues of compatibility.  The typical real
situation is “plug-and-pray,” the more common epithet.

plug-in:  A third-party software program sold to add additional function to an existing, larger
software suite.  An example of a plug-in is the Waves™  TDM-based plug-in audio diagnostic
suite which runs under ProTools.™  There are two types of plug-in:  file-based and real-time.
The former are usually less expensive, less powerful and require the user to wait while the ef-
fect is calculated by the computer.  The plug-in modifies the data on the disk (destructive edit-
ing), but no additional hardware is required to use the plug-in.  Real-time plug-ins allow the
user to hear the effect while the music is playing.  The real-time plug-ins require dedicated
hardware to process the sound in, of course, real-time.  Changes in the original file are not
saved unless requested by the user (non-destructive editing.)

poco a poco:  Italian for “little by little,” or gradually.

point source:  A hypothetical sound source which is very small compared to the wavelengths

of the sound it is radiating, and which is radiating into a free-field.

polarity:  The orientation of magnetic or electric fields.  The polarity of the incoming audio
signal determines the direction of movement of the loudspeaker cone or microphone diaphragm,
i.e., the sign, + or -, of the transducer’s output voltage when a positive sound pressure strikes
the microphone, or when the speaker cone is pushing away from the cabinet.  Note that on a
microphone, by convention, positive sound pressure, which pushes the diaphragm in, makes a
positive voltage on mic pin 2 with respect to pin 3.  A sound is perceived as being louder if the
largest peaks are in positive polarity, that is when the compression portion of the sound wave is
pushing the speaker cone outward, toward the listener.  Polarity reversal is the same as phase-
reversal, or 180˚ of phase-shift.

polarizing voltage:  The DC voltage supplied in opposite polarities to the plate and diaphragm
of a condenser microphone (via phantom power) or electrostatic loudspeaker.