PA : (1) Public Address. The distribution of audio signals to loudspeakers for an audience.

(2) A system of equipment, including a mixing desk, amplifiers, loudspeakers, etc., assembled to provide PA sound.

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PA version : Public Appearance version. A prerecorded tape or just the instrumental backing of a song, with which a solo vocal artist can sing during public appearances to promote a record.

 

Packet : A unit of data encapsulated by a physical network protocol header provides control and touring information for directing the packet through the fabric while the trailer contains data to ensure packets are not delivered with corrupted contents. Other “packetized” transport mechanisms include IP, the Internet protocol and the new VXA tape format.

 

pad : (1) A switch or knob that lowers the level of an incoming signal before it reaches the rest of the circuitry. A short name for an insertion loss. Pads are used between audio devices if there is a danger of the output of one device causing a signal overload in the input of the other device. An input pad is also called a pot. (2) A sustained chord part which provides harmonic padding in a piece of popular music. (3) Drum pads.

 

paddles : See PEC/Direct.

 

PAF : Prearbitrated function

 

PAL : Phase-Alternating Line. The UK television broadcast standard. Uses 625 lines at a frame rate of 25fps.

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PAM : Pulse Amplitude Modulation. The first stage in digital sampling, in which pulses of fixed- width have their amplitude modulated by an analog signal, i.e., the height of the pulse is determined by the amplitude of the signal. It is followed by an encoding stage known as PCM.

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PAN : A dedicated on-line internet service provider for the music industry.

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pan : Short for panorama. (1) (noun) Refers to the left-right placement of a sound.

(2) (verb) Moving a sound from stereo-center to one side or the other, either on a mixer or on a synthesizer, sequencer, etc. Usually this is not completely effective as panning alters only the relative amplitude of the sound left to right, and not the crucial aspect of delay. See Haas effect.

(3) One of the defined MIDI Controller Change messages assigned to the parameter in a synthesizer which determines the stereo image of the sound, effectively making that controller a panpot.

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pancake : A 10 1/2" reel of recording tape without the reel flanges. Recording studios often buy tape in this form and spool it onto smaller reels as it is used.

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panic button : A hardware or software feature that simultaneously sends All Notes Off and Reset All Controllers commands to a MIDI system. Because some instruments don’t respond to All Notes Off commands, some panic buttons are designed to send Note Off messages (0-127) on all channels as well.

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panpot : Short for panoramic potentiometer. An audio mixer control which is used for positioning the channel’s signal somewhere between the right and left speakers. See pan.

 

paper leader : See plastic leader.

 

parabolic reflector : A dish-shaped structure used to focus sound waves onto a microphone. The reflector faces the sound source and the microphone is mounted backwards, i.e., pointing at the center of the parabola. Used mainly to gather sound in outdoor locations, such as in wildlife recording. A satellite receiving dish for television uses a similar principle to focus incoming electro-magnetic waves.

 

parallel : In the connection of one signal or power source to more than one device or destination, the wiring configuration in which the input leads of all the devices meet at a common point. Signal or power routed to this point flows directly to each device. The opposite of seriales wiring, in which the source is wired to the input of one device, whose output becomes the input for the next, etc.

 

 

 

 

 

 

 

 

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parallel connection : See bridging.

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parallel interface : A protocol for transmitting data whereby all bits in a word (typically two or more bytes) are sent simultaneously. This method is generally more expensive to implement than serial protocols as the connectors and cable must have a pin/wire for each bit, plus a few extra for ground, handshaking, etc. This cost is offset by the faster transmission times.

 

parallel port : A connector on a PC-type computer which is used to connect devices which use a parallel interface, such as some MIDI interfaces and parallel printers.

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parameter : A user-adjustable quantity that governs some aspect of a device’s performance. Normally, the settings (values) for all of the parameters that make up a synthesizer patch can be changed by the user and stored in memory, but the parameters themselves are defined by the operating system and cannot be altered.

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parametric equalizer : A parametric equalizer is a sweep bandpass EQ, except that a third control is added to allow the width of the filter response to be adjusted. The width of the filter response is its Q value to be adjusted. , and Bbecause the filter response is curved, the actual frequency width is measured in increments of 3dB. Also called a peaking equalizer. See equalizer, graphic equalizer.

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parasitic oscillation : A malfunction occurring in some audio devices, especially power amplifiers, in which the device will generate an ultrasonic signal during a part of the audio signal, only when the input signal is present and only during part of the audio waveform. Although the ultrasonic component is not directly audible, its existence modulates the signal, causing audible distortion and is potentially damaging in the signal and can to burn out tweeters.

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parity check : In digital recording, one or more bits of data derived from the audio sample and appended to it as a part of the data16-bit word. The parity bit allows error-detection circuitry to determine whether the audio bits are correct, and therefore, whether they should be sent on for D/A conversion, discarded, or repaired. Also called a parity code.

partial : One of the sine wave components: the fundamental, harmonic, subharmonic, overtone, or a tone at some other frequency which forms party of a complex tone. Any component of a sound, whether or not it is an integer multiple of the fundamental frequency is a partial. The fundamental frequency is the first partial of a tone.

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PASC : See Digital Compact Cassette.

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passband : The passband of a filter is the frequency span that the filter passes, or the range of frequencies not attenuated by the filter. The passband is usually measured between the points where the response is 3dB down in amplitude relative to the maximum level. See rolloff frequency.

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passive : A device is called passive if it contains no amplification circuitry and a signal suffers insertion loss in passing through it, i.e., more energy goes into the device than is available at its output. This is opposed to an amplifier or other device which has the potential for at least unity gain. Many audio equalizers are passive, as are most crossover networks.

Passive devices in general do not add any appreciable nonlinear distortion or noise to the signal, but they have so much attendant insertion loss that additional amplification is needed, and this always contributes some noise and distortion.

Passive devices can and do cause phase distortion, however. As opposed to active.

 

passive crossover : See crossover network.

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passive equalizer : An equalizer that employs only passive electronic components, i.e., resistors, capacitors, and/or inductors. Since these components require voltage, passive equalizers can only cut each operating band, the. The output signal level is necessarilythus lower than the input level. See active equalizer.

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patch : (1) (verb) To connect together, as the inputs and outputs of various modules, generally with patch cords. (2) (noun) The configuration of hookups and settings that results from the process of patching, and by extension, the sound that such a configuration creates. Patch is most often used to denote a single sound or the contents of a memory location that contains parameter settings for the sound, even on an instrument that requires no physical patching. A synonym for sample or program.

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patch bay : A group of similar receptacles, or jack, in an audio system. The act of plugging and unplugging the patch cords is called patching. Also called a router, jack field, or jack bay. Increasingly, physical patching is being replaced by digital routing.

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patch cord : A short cable, typically fitted with a phone plug or TT connector at each end, used to make a connection between two points on a patch bay.

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patch map : A map with which any incoming MIDI program change message can be assigned to call up any of an instrument’s patches. This is a table set up by the user with entries such as 1=3, 2=2, 3=984, etc. See patch mapping, MIDI Mapper.

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patch mapping : A Program Change message is limited to only 128 values, while some synthesizers can store many thousands of separate patches. This would mean that only 128 of the programs could be accessed via MIDI. Patch mapping is a process whereby a given program change number received by a MIDI device can be linked to any one of the available patches, as determined by a patch map. To get beyond the 128 limit, the MIDI Continuous Controller message, Bank Select, has been defined for selecting different banks of sounds prior to sending a program change number.

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patch point : A location in an electronic circuit at which access to the circuit is provided by a jack in the patch bay or console channel strip. See normalled connection, output.

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path length : The distance between a sound source and the listener or microphone. See near-field, far-field.

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pattern looping : A digital composition technique whereby long, looped samples are mapped into a sampler along with other samples such as bass riffs, drum variations, and solo samples (vocal sounds, effects, etc.) The different loops and solo sounds are brought in and out via a keyboard to create a finished composition.

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PCI : Peripheral Component Interface. An internal bus architecture for PCs and the Mac commonly used for digital audio cards.

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PCM : Pulse Code Modulation. A technical term for sampling. Any digital method of encoding and decoding the amplitude of an audio signal. For example, an 8-bit PCM yields amplitude values of 0-255, and produces attendant sampling errors and quantization errors. PCM cards are always ROM, and contain only sampled waveforms, contained in a wavetable. See PWM, split-band. See also PAM.

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PCM-F1 : A reference to the (discontinued) Sony digital recording system which used an EIAJ-format, 16-bit PCM processor to convert audio into a digital form that can be stored on consumer videotape. The first attempt at digital audio.

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PCMCIA : personal computer memory card international association. The preferred term is PC Card; a 32-bit implementation is called a cardbus. A credit-card-size interface commonly found in notebook computers. They are primarily used for modems and network interfaces (and storing programs in synthesizers); this specification has historically been inhospitable to audio devices even though a handful of successful advices do exist.

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PD : See ProDigital.

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PDL : Projectionist Dummy Loader. Union designation for the person in a film recording facility who functions both as projectionist and as a machine room operator.

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peak : Peak value is the maximum instantaneous excursion from zero of an audio waveform, as measured by a peak meter (PPM). The peak value of a sound is also the maximum instantaneous pressure excursion of the sound. See crest factor, VU meter.

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peak expansion : The adjustment of an expander’s threshold so that most program material passes through unaffected, but peaks or transients are heavily expanded. Used to restore peaks to program material that has been overly compressed.

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peak hold : A function of some volume indicators that indicates the peak level of the signal and holds that level until it is either exceeded by a higher peak or the indicator is reset by a time delay or manual reset.

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peak level : See peak.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

peak-to-peak value : A measure of the highest positive-to-negative voltage swing in any specified segment of the program signal. Twice the absolute value of the greater voltage reached by an adjacent positive or negative transient peak.

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peaking equalizer : Another name for a parametric equalizer.

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peanut microphone : See Lavalier microphone.

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Pebkac : problem exists between keyboard and chair. a.k.a., operator error. Also known as code 18 (operator error), which refers to the human entity screwing up, 18 inches from the display.

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PEC/direct : Photo-Electric Cell. In film re-recording, the act of switching between playback from the recorder in playback mode.

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pedal : (1) A foot-operated lever on a musical instrument. On a piano, the indication, L, means to use the sustain pedal.

(2) Strictly, pedal point. A sustained or continually repeated note that occurs throughout a passage of changing harmonies. Commonly on the dominant note, it creates a feeling of tension; on the tonic, it creates a sense of repose. It often occurs in the bass; if played above the other parts, it is known as an inverted pedal. Also known as a drone in folk music.

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pedalboard : A large and widely spaced keyboard designed to be played by the feet, commonly found on organs, although also available as a type of MIDI controller. Generally used to play bass notes.

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pentatonic : A scale in which the octave is divided into five notes.

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percentage quantization : A method of quantization in which notes recorded into a sequencer with uneven rhythms are not shifted all the way to their theoretically perfect timings, but instead are humanized, with the amount of shift being dependent on the user-selected percentage, called quantization strength.

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perceptual coding : Any audio compression scheme that deletes audio frequencies that are masked by other, more dominant frequencies, and thus are not perceived by the listener. See split-band coding, transform coding, temporal masking, MPEG, PASC, ATRAC, and AC3.

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Perceptual sub band/transform : Codecs designed to reduce the data rate and/or size of a digital audio file. The encoder applies a psychoacoustic model to estimate whether, in any particular band of frequencies, the signal strength in that band I above or below the perceptual threshold relative to adjacent frequency bands. If the signal is above that masking threshold, than a spectral coefficient or value is generated to represent the signal in that band and the coefficient becomes the stand-in, or representation of, the actual audio in that band, if the signal is not above the predicted masking threshold, then that band of frequencies is tossed out to reduce the final size of the essence.

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percussion waveform : A percussion waveform is generated through the random noise generator of a synthesizer. If a second-order (two-pole) filter that has a high Q (low loss) is used after the noise generator, it simulates a drum. If repeated at a predetermined rate, it is called a repeat-percussion waveform, which constitutes the basic rhythm section of a synthesizer.

perfs : Perforations. Sprocket holes in motion picture film.

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period : In a waveform that repeats a particular pattern over and over, the time required for one repetition of one wavelength is called the period. The waveform is then called periodic, and can be expressed as the summation of a series of sine waves called harmonics. The length of the period of the waveform varies inversely with frequency.

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perspective : The effect of front-to-back depth in an audio signal. This may be inherent in the stereo image or may be artificially achieved by varying the amount of direct sound and reflected sound. The indirect signal may be obtained from mics places away from the source, or may be generated by a reverberation unit.

PFL : See pre-fade listen.

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PFX : Production sound effects. Tracks of sound effects, as opposed to Foley, music, or dialog, which get mixed into the final DME tracks of a film soundtrack. Sometimes Foley gets mixed into the dialog stem, and PFX into the effects stems to separate the effects which correspond with the dialog from BG/walla effects.

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phantom image : A monophonic sound panned equally to both speakers.

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phantom power : DC power (usually 9V to 52V) supplied to condenser microphones by a preamplifier close to the microphone, necessary due to the extremely high impedance of the microphone, via the signal wiring of the microphone.

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phase : Phase is defined as the time relationship between two corresponding points on a continuous wave, or the angular, or time, displacement between the voltage and current in an AC circuit. A sine wave signal is the simplest possible waveform and goes through 360˚ in one cycle, whereby it returns to its starting point. Another way of saying the same thing is that the signal has gone through 360˚ of phase angle, or phase change. The phase is actually a measure of time, 360˚ equaling one period of the signal. The time represented by a phase change of a certain number of degrees is thus dependent on frequency.

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phase cancellation : An attenuation of signal components resulting from combining out-of-phase waveforms. When two waveforms are mixed, their harmonics are added. If these signals are out-of-phaseout of phase with each other, the amplitudes of the harmonic components differ at various times, (as determined by the phase relationship.) If the added harmonics have the same polarity, the signal is reinforced at those frequencies, and vice-versa. See phase distortion.

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phase coherent : A condition encountered in the summation of two or more in-phase signals, in which the signals combine constructively, with little or no phase cancellation.

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phase compensation : In some tape recorders, there is a special equalizer whose purpose is to minimize phase distortion.

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phase distortion : An effect caused when phase-shift in an audio device is not a linear function of frequency. In other words, different frequencies experience different time delays. This changes the waveform of the signal and is especially injurious to transients. Most transducers produce significant phase distortion. As low frequencies travel slightly faster than high frequencies and as air absorbs high frequencies more readily than low ones, the more delay there is between low frequencies and the higher harmonics of a sound, the sound becomes progressively more smeared and is perceived as more distant.

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phase distortion synthesis : A form of modulation synthesis in which the spectrum of a DCO’s output signal is altered by modulating the DCO’s clock frequency within each cycle, while the over-all frequency is kept constant. The oscillator’s clock frequency speeds up and slows down, producing rapid phase changes as the waveshape is alternately compressed and expanded (distorted) to fit within the regulated period. Popularized by the Casio CZ-series synthesizers.

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phase inversion : See phase reversal.

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phase invert : See phi.

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phase linear : The ability of an audio device to pass a signal without causing phase-shift.

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phase manipulation : A technique used by aural enhancers which realigns the relative phase of existing harmonics.

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phase meter : An electronic circuit and display that compares two incoming signals and shows the phase difference between them.

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phase modulation : Also known as phase-shift. An alteration of the phase of partials of a signal. Virtually all signal processing devices will cause a certain amount of phase modulation, none of them being completely phase linear. See also PIM.

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phase reinforcement : The opposite of phase cancellation. An reinforcement of signal components resulting from combining phase coherent waveforms. When two waveforms are mixed, their harmonics are added. If these signals are not perfectly in- phase with each other, the amplitudes of the harmonic components differ at various times, (as determined by the phase relationship.) If the added harmonics have the same polarity, the signal is reinforced at those frequencies.

Phase Response the first derivative of the amplitude.

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phase reversal : (1) The condition where the connection in one channel of a stereo signal are reversed. This is most likely to happen at the loudspeaker, and results in phase cancellation, particularly apparent in the bass.

(2) In electronic signals, changing the polarity of the signal from positive to negative or vice versa, thereby causing a reversal in polarity of the signal. When viewed on an oscilloscope, the waveform flips with respect to the time axis. Also called polarity reversal or phase inversion. See common mode, out-of-phase. The pair of loudspeakers on the left are in phase--the speaker cones cause compression and rarefaction the surrounding air in unison. Those on the right are out-of-phase, causing the air compression generated by one speaker to be cancelled by the rarefaction generated by the other.

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phase reversal switch : A switch, usually found in a balanced line, that allows the user to interchange the two conductors, causing a 180 degree shift in phase of the signal. This is often a feature of recording consoles to allow the engineer to optimize the phase relationships of multiple microphones placed in close proximity to each other, i.e., mics likely to pick up substantially identical signals, such as on a drum kit. See phase cancellation.

 

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 tonecode wave is held in phase with the sync tonecode wave 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.

 

phase- lock : See sync-lock.

 

Phase-Alternating Line : See PAL.

 

phase-locked loop (PLL) : A closed-loop electronic circuit that automatically adjusts and locks the frequency of an oscillator to the correct frequency for receiving a signal. The PLL is the preferred FM detector circuit in commercial systems today as it requires no tuned circuits, hence does not require alignment. It normally has high amplification which produces a strong output audio signal. Since it does not respond to amplitude variations, it also provides limiting action.

 

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 flanging.

(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.

phasing : See phase-shifter/phaser.

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phi : An abbreviation for phase. Some control consoles have a small switch on their input modules labeled " " that inverts the polarity of the signal in that channel. This is to allow all the signals being mixed together to have the same polarity regardless of wiring errors in patch panels and microphone cables and in the microphones themselves. See out-of-phase, phase cancellation.

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phon : A unit which takes account of the ear’s nonlinear response to the loudness and frequency of a sound. The phon uses a decibellogarithmic, i.e., logarithmic, scale which is based on the level of intensity of a given sound that corresponds to dB rating of a pure tone at 1kHz, subjectively judged to be of the same loudness. An increase of one phon is about the smallest increment 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.

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phon lines : See equal loudness curves.

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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 processors and mixers. See also TRS, TT.

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phono connector : Also called an RCA connector, these are generically known as pin-jack connectors 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 complex 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.

PI Program Identification. See RDS.

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pick-up : See DI, piezo pick-up.

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Picture Start : See LFOP, sync pop.

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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 electro-magnetic 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.

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

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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.

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pilot tone : A 60Hz sine wave is recorded on one track of a tape which is used for motion picture 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 syncphase 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 : To bounce tracks in a multitrack recording.

(2) 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 alternation. 

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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.

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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.

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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.

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Pit Signal Processing (PSP) : See digital watermark.

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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 "cycles 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 impression 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 prevent slippage between original and print film as they wind around various sprocket wheels in the contact printers used to make most prints.

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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.

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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.

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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.

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

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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 zero0s in the data. Audio samples, location and synchronizing information, bands and indexing, visual information, etc. are all encoded in the pits.

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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 image.

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planar loudspeaker : A type of dipole loudspeaker design which combines aspects of both dynamic and electrostatic designs. The planar speaker consists of a large plastic sheet with conducting wires embedded 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.

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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.

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plate : See back plate.

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plate reverb : An electromechanical substitute for an acoustic reverb chamber, where electronically 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 reverberation 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 reverb. The plate has a characteristic metallic, bright sound. Other substitutes were spring reverbs and slap echo devices.

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platter projection : See projection.

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playback : (1) The amplified reproduction of any type of sound recording.

(2) The reproduction 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 reproduction 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.

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playback head : The head on a tape recorder that is used to detect the varying remnant magnetism present on the tape. The output of this head is then amplified and heard as the recorded program.

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playback-equalization : See record-equalization.

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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) which gives the order in which sections from various recording takes will be used. It will usually include timing information which may be locked to timecodetime code, as well as information about type and duration of crossfades, etc. Both also known as an EDL.

plosive : See pop filter.

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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.

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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 effect is calculated by the computer. The plug-in modifies the data on the disk (destructive editing), 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.)

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poco a poco : Italian for "little by little," or gradually.

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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.

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polar pattern : A circular, two-dimensional plot that indicates the directional response of a transducer, such as a directional microphone. Whole polar patterns are commonly used to show microphone responsepick-up patterns,; they also can indicate the dispersion of a speaker. In the diagram below, points X and Y indicate response nulls in the hypercardioid microphone, which represent optimal angles for the placement of stage monitors. A good microphone should have a similar polar pattern from 200Hz to 10kHz, otherwise the mic will produce noticeable off-axis coloration. Also called a polar diagram or response pattern. The cardioid pattern microphone is most sensitive to sounds coming directly from the front and least sensitive to sounds coming directly from the rear. The hypercardioid is most sensitive to sounds coming directly from the front and least sensitive to sounds coming in the direction of X and Y, a good place for stage monitors.

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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 asequal to a 180˚ phase-reversal, or 180˚ of phase-shift.

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

pole : A portion of a filter circuit. The more poles a filter has, the more abrupt its rolloff slope will be. Each pole causes a slope of 6dB per octave; typical filter configurations are two-pole and four-pole (12dB/octave and 24dB/octave, respectively). See order.

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Poly Mode : A MIDI reception mode in which a module responds to note messages on only one channel, and plays as many of these notes at a time (polyphonically) as it can. In a guitar-to-MIDI converter, Poly Mode allows multiple strings to share the same channel. Compare with Mono Mode.

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poly pressure : Polyphonic pressure. A type of MIDI Channel Voice message in which each key senses and transmits aftertouch data independently. With poly pressure, if a chord is played, pressing into the top note, only this note will be modulated without affecting the others. Expensive to implement, so rarely seen. Also called poly aftertouch or key pressure. Compare with channel pressure.

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polyphonic : (1) Music which simultaneously has more than one independent melodic line.

(2) Capable of producing more than one note at a time. On most electronic organs, all of the notes can be sounded polyphonically at once, but all synthesizers place a limit on how many voices of polyphony are available. General MIDI-compliant synthesizers are required to provide 24 voices of polyphony. C. Compare with multitimbral.

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pop a track : The act of aligning a two-pop exactly nine feet from the start mark, either on mag film or on a bench, or in a digital audio workstation.

 

pop filter : A device that is used to reduce the "popping", distortion caused by overmodulation of a microphone, usually as a result of placing it too close to the sound source. It commonly occurs with the vocal pop screen, windscreen, or windshield.

 

popcorn noise : Film expression for ambient noise in a theater environment that influence the low end of the dynamic range, and how soft a sound will be heard (or "read") in an actual theater. See Little Old Ladies with Umbrellas.

 

popping : See pop filter.

 

port : (1) An opening in the front surface or baffle of a loudspeaker enclosure, called a ported enclosure.

(2) One or more openings on the body of a unidirectional microphone, either rear-entry or side-entry. Passing through the port(s), sound waves reach the rear side of the diaphragm and, through phase cancellation or reinforcement, contribute to its directional response pick-up pattern. See acoustic labyrinth.

 

portamento : (1) A continuous movement in pitch from one note to another without step. Instruments with notes of fixed pitch, such as the piano, are unable to do this, but the human voice, fretless instruments, e.g., violins, and instruments fitted with slides, e.g., trombones, can. It is a different effect from glissando.

(2) See glide.

(3) One of the defined MIDI Controller Change messages used to switch a synthesizer’s portamento on or off.

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Portamento Time : One of the defined MIDI Controller Change messages assigned to the parameter in a synthesizer which determines the time taken for portamento to occur.

Ported speaker enclosures are vented or ported to allow the speaker to ‘breathe’ and relieve pressure created.

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positional reference : A signal that provides location information that various devices can use to establish synchronization during playback and recording.

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post : (1) Means "after," as opposed to pre. In recording studio parlance, it is used to indicate that the signal has already had the designated effect added, such as post-equalization, post-effects, or post-fader. Also used as an abbreviation for post-production.

(2) Binding post. A connector, consisting of a threaded shaft and nut, used to terminate bare wire. Usually found on loudspeakers and occasionally amplifiers. See pigtail.

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post de-emphasis :  The same as de-emphasis.

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post-fader listen : Also called after-fade listen AFL. Signal routing within a mixing console to allow audio signals to be monitored at the level set by the fader on that input, rather than monitoring the level coming to the input, as in pre-fade listen, Aux sends are usually monitored post-fader. Because of the ambiguity of the abbreviation PFL, be sure to use AFL (after-fade listen) for post-fade listen as PFL is generally taken to denote pre-fade listen.

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post-fader send : See effects send.

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post-production : (1) In audio, a term used for tasks which have to be done after mixing is complete and the master tape has been made. These include further editing, grouping of individual tracks into an album, and for CD, the addition of subcode.

(2) Any work on a recording, film, or video that is done after the main recording session or filming is completed. Typical post-production work can include editing, mixdown, looping, sound cutting, making of titles, etc."

 

post-roll : (1) The number of beats/amount of time a sample ends after the playback-endstop ping marker.

(2) In SMPTE timecode synchronization for videotape post-production, thea number of seconds and/or frames specified which are automatically added to any timecodetime code address subsequently specified as a record-out point. Thus, when inserting dialog or music, on each take master and slave machines will continue to roll for the post-roll duration after recording is stopped. This prevents the type of wow that occurs when a transport is stopped while the electronics are still recording. Some brands of synchronizer add the post-roll to the mark-out rather than the record-out location.

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post-score : To compose and/or produce a musical score or jingle after the film or videotape for the production has been shot, and usually after a fine cut is completed. The composer can then spot cues, take counts, locate hits and really tailor the music to the visuals.

 

post-stripe : To re-lay the mixed soundtrack onto the edited video master, or onto a copy made from it.

 

post-sync : Post-synchronization. (1) ADR recording with M&E made to synchronize with an existing film or video tape, usually for translation of a foreign-language film. This term is used mainly in Europe, while in the U.S., the term ADR is used as a synonym.

(2) The recording of sound tothat be added to the synchronous sound.

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pot : Potentiometer. A device (commonly attached to a knob or slider) used to adjust some aspect of the signal being passed through it, or to send out a control signal corresponding to its position. A variable resistor, usually controlled by a rotary knob, is used extensively as a volume control, tone control, etc. The term is also sometimes used for a step-type attenuator.

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power : (1) Electric power: The time time-rate of doing work or the rate at which energy is used. A watt of electrical power is the use of one joule of energy per second. Watts of electrical energy equals volts times amperes. See Appendix B.

(2) Acoustic power: The number of watts of energy produced by any sound source or transducer. See acoustic intensity.

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power amplifier : A device n amplifier that accepts a low-level audio signal and strengthens, or amplifies, it to a suitable voltage and current level adequate to drive a loudspeaker or similar load. The four key parts of a power amplifier are the input stage (voltage gain), driver stage (phase splitting), output stage (load response), and power supply. See preamplifier, active, differential amplifier, integrated amplifier, combining amplifier.

 

power bandwidth : The bandwidth of an audio device such as a power amplifier, measured while delivering its full rated load. This is limited by the slew rate of the device and is always narrower than the small signal bandwidth.

 

power factor : See also watt, VA.

Power Fader Controls volume relation between front and rear speakers connected to built-in amplifier.

 

power level : See level.

power loaders System loads and ejects CD or Tape automatically.

 

power ratio : See decibel, voltage gain.

 

PPM : Peak Program Meter.

 

ppq : Pulses Per Quarter-note. The usual measure of a sequencer’s clock clock resolution. Sometimes written as ppqn.

 

PQ subcode : These control bytes contain the timing information which allows the CD player to cue instantly to the beginning of each selection, display the selection’s number and running time, and provide a continuous display of elapsed time. See Control and Display signals.

 

Pre-amp : holds controls for volume, bass and treble but has no on-board amplification.

pre-amp fader in cars, adjusts front/rear balance at pre-amp level, used in combination with pre-outs and external amplifiers.

 

pre-amp output : in cars, a preamp output (pre-out) on a head unit allows the addition of an amp or other peripherals when system building.

 

pre-delay : In reverberation, the time between the incident sound delay and the first sound reflection before any reflected sound is heard.

 

pre-echo : (1) Depending upon the width of each frequency band in a transform coding scheme, it is possible for the decoder to produce variable amounts of pre-echo. For example, a sudden transient that has its rising edge contained within a frequency band:. The codec quite correctly detects the transient’sits presence and codes the information within the appropriate band, and also uses that information to re-use bits from surrounding masked envelopes. Upon decoding, the output level is turned on the for complete duration of the coded frequency band, which means that the signal will be heard before the arrival of the actual transient. Such pre-echoes sound very much like analog tape print-through and may produce unacceptable results, particularly on material containing large numbers of sharp level excursions.

(2) In room acoustics, any early reflections of sound that occur within about 40 ms, the shortest time for which the ear can distinguish two non-simultaneous sounds. Some digital reverb devices include simulated pre-echoes as a part of their hall simulation program.