P2P (peer-to-peer) - A network term popularly used to mean an equal access network where every node can send/receive data at any time without waiting for permission, i.e., each node can act as a client or server.
p - The symbol for pico, one trillionth (10-12)
PA - public address.
PA-232 - An RS-232-based variant of the PA-422 AES standard.
PA-422 - A pro audio implementation of Electronics Industries Association EIA-422 interconnection standard, defined and adopted by the Audio Engineering Society as AES Recommended practice for sound-reinforcement systems - Communications interface (PA-422) AES 15-1991 (ANSI S4.49-1991).
PAC (Perceptual Audio Coder) - Proprietary bit reduction scheme originally developed by Elemedia, a subsidiary of Bell Labs.
packet - An Ethernet packet consists of two kinds of data: control information and user data (also known as payload). [Wikipedia]
pad - A passive network that reduces the voltage (or power) level of a signal with negligible distortion, but with insertion loss. Often a purely resistive network, although any combination of inductors, resistors and capacitors are possible, a pad may also provide impedance matching.
PAL® (programmable array logic) - Original registered trademark of Monolithic Memories Inc. (now owned by Advanced Micro Devices, Inc.) for their fuse-link once-programmable logic parts that have a programmable AND array, but a predefined OR array.
PAL/SECAM (phase alternated line/sequential couleur avec memoire or sequential color with memory) - The European and Australian standard for color formatting for television transmission developed in the 1960s and used most everywhere in the world except the U.S.A. and Japan, which use NTSC.
PALM Expo (Pro Audio Lighting Music) - China's Largest International Exhibition on Pro Audio, Light, Music & Technology.
PALME Conferences (Professional Audio, Light, Music and Entertainment) - International exhibitions held in Middle East, Asia and Vietnam.
PAMA (Professional Audio Manufacturers Alliance) - The voice of the professional audio manufacturing community, managed by InfoComm.
pan (panoramic) control - A control found on mixers, used to "move," or pan the apparent position of a single sound channel between two outputs, usually "left," and "right," for stereo outputs.
Panatrope - Designed by RCA and sold by Brunswick in 1925, this was their name for the first phonograph player to use electricity to reproduce the sound stored on the record.
PANS (personal area network system) - Interconnection of IT (information technology) devices within the range of an individual person.
PAQRAT® - A registered trademark of Rane Corporation for their recording converter devices, RC 24T & RC 24A, that converted AES/EBU stereo 18-24 bit digital audio two track data into 16-bit compatible four tracks for recording and playback on 1st-generation 16-bit modular digital multitrack tape machines such as Alesis ADAT and Tascam DTRS (DA-88) models.
parabolic reflector - Shape and mathematics behind antennas and special purpose microphones and sound mirrors.
paragraphic - Parametric equalizers which allow control of center frequency but not bandwidth and fitted with slide controls.
parallel circuit - Two-terminal elements are connected in parallel when they are connected between the same pair of nodes. [IEEE]
parallel interface - The printer port in the PC world. A parallel port conforming to the quasi-standard called the Centronics Parallel Standard (there is no EIA standard). Originally a 36-pin connector, now more often a D-25 type connector. A parallel (as opposed to serial) interface transfers all bits in a word simultaneously.
parametric audio coding - An audio coding technology originally developed for speech. Basis of MPEG-4 standard.
parametric equalizer - First designed and named by George Massenburg in 1969, a multi-band variable equalizer offering control of all the "parameters" of the internal bandpass filter sections. These parameters being amplitude, center frequency and bandwidth. This allows the user not only to control the amplitude of each band, but also to shift the center frequency and to widen or narrow the affected area. Available with rotary and slide controls.
parity - A redundant error detection method in which the total number of binary 1's (or 0's) is always made even or odd by appending one or more bits.
Parkinson's Law - "Work expands so as to fill the time available for its completion."
partial or partial tone - A tone produced on a stringed instrument by lightly touching an open or stopped vibrating string at a given fraction of its length so that both segments vibrate.
pascal - Abbr. Pa. The International System unit of pressure equal to one newton per square meter.
Pascal, Blaise - (b. 1623-1662) French philosopher and mathematician. Among his achievements are the invention of an adding machine and the development of the modern theory of probability.
passband - The range of frequencies passed by an audio low-pass, high-pass or bandpass filter. Normally measured at the -3 dB point: the frequency point where the amplitude response is attenuated 3 dB (decibels) relative to the level of the main passband. For a bandpass filter two points are referenced: the upper and lower -3 dB points. The -3 dB point represents the frequency where the output power has been reduced by one-half.
passive component - A component that does not require power to operate, e.g., a resistor.
passive crossover - A loudspeaker crossover not requiring a power supply for operation.
passive equalizer - A variable equalizer requiring no power supply to operate. Consisting only of passive components (inductors, capacitors and resistors) passive equalizers have no AC line cord.
PASTI (public address speech transmission index) - Chiefly British term for STIpa.
patchbay or patch panel - A flat panel, or enclosure, usually rack-mounted, that contains at least two rows of 1/4" TRS connectors used to "patch in" or insert into the signal path a piece of external equipment (really dense configurations use 4.4 mm miniature or "bantam" jacks).
Paul, Les - (b. 1915-2009) [Birth name: Lester William Polsfuss] American musician legend who was also a gifted songwriter and inventor. His pioneering work on the solid-body electric guitar and multitrack recordings changed the pro audio industry forever.
payload - An Ethernet packet consisting of two kinds of data: control information and user data [Wikipedia]
PBX (private branch exchange) - Term referring to hardware allowing several telephones to be connected to a smaller number of lines.
PC (personal computer) - Original term coined by IBM to describe their first personal computers; now used to mean all IBM-compatible personal computers, or any personal computer.
PCB (printed circuit board) - An electric circuit in which the conducting connections have been printed or otherwise deposited in predetermined patterns on an insulating base. [AHD]
PC-DOS® (personal computer disk operating system) - IBM's trademarked acronym for their PC operating system. If PC-DOS runs on an IBM compatible, it is then called MS-DOS.
PCI (peripheral component interconnect) - Intel-designed high performance CPU interconnect strategy for "glueless" I/O subsystems. A 32- or 64-bit local-bus specification, characterized by being self-configuring, open, high-bandwidth and processor-independent -- allowing for modular hardware design.
PCM (pulse code modulation) - A conversion method in which digital words in a bit stream represent samples of analog information. The basis of most digital audio systems, first invented by Alec H. Reeves in 1937.
PCMCIA (Personal Computer Memory Card International Association) - The association and first name given to the standardized credit-card size packages (aka smart cards) for memory and I/O (modems, LAN cards, etc.) for computers, laptops, palmtops, etc. Nicknamed PC-Card, which is now the preferred term.
PDA (personal digital assistant) - A small palmtop-like computer designed for specific tasks such as a pocket calculator. Other examples include personal electronic diaries, memo takers, communicators, web browsers, dictionary-translators, etc. Apple's Newton is a PDA. IBM named theirs personal communicators.
pdf (probability density function) - The name given to a mathematical function that defines a continuous interval (i.e., one without gaps), or curve, such that the area under the curve (and above the x-axis, i.e., the probability is always positive) described by the function is unity, or equals one, or 100%. All possibilities are represented. PDF files (portable document format) Suffix letters used (.pdf) to indicate an Adobe Acrobat document.
peaking response - Term used to describe a bandpass shape when applied to program equalization.
peak program meter (PPM) - An audio meter originally developed in Europe to accurately measure and display peak audio signals (as opposed to average audio signals).
peak PSD (power spectral density) - PSD measured in a time interval less than one second.
PEAQ (perceptual evaluation of audio quality) - Term for the ITU-R recommendations for the objective measurement of perceived audio quality for perceptually coded digital audio signals. Popularly called the new "electronic ear" to provide yardstick values for digitally coded audio quality, there are a series of recommendations covering various aspects of this method (e.g., ITU-R Rec. BS.1387, ITU-R Rec. BS.1116 and ITU-R Rec. BS.562-3).
Pearson, Donald ("Dr. Don") Michael - (b.1942-2006) American live sound engineer who pioneered high-fidelity large-scale sound reinforcement systems.
Pease, Bob - (b. 1940-2011) Famous American engineer known for his innovative analog IC designs, popular for his "Pease Porridge" column in Electronic Design magazine, and writing about hiking and biking in exotic places like Tibet.
PEC (parallel earth conductor) - Modern best practices for EMC in installations (per IEC 61000-5-2:1998) require the use of trays, conduits and heavy-gauge earth conductors, known as "parallel earth conductors" (PEC) to divert power currents away from cables and their shields.
PEC (protective earth conductor) - Conductor to be connected between the protective earth terminal and an external protective earthing system.
peer-to-peer (abbreviated P2P) - A network term popularly used to mean an equal access network where every node can send/receive data at any time without waiting for permission, i.e., each node can act as a client or server. An example would be a group of computers that communicate directly with each other, rather than through a central server.
pennywhistle - An inexpensive fipple flute, usually having a plastic mouthpiece and a tin body.
pentode - A vacuum tube consisting of five elements: cathode, control grid, screen grid, suppressor grid and plate.
Percentage Articulation Loss of Consonants (%ALCONS) - A term first published in the paper by V. M. A. Peutz. "Articulation Loss of Consonants as a Criteria for Speech Transmission in a Room," J. Audio Eng. Soc., Vol. 19, Dec 1971. It is a measure of room speech intelligibility based on the measured RT60 time and dimensions of the room, combined and expressed as a percent, where 0% (no loss of consonants) is perfect, 10% is poor, and 15% is intolerable. Popularized by Syn-Aud-Con's Pat Brown who teaches how to use it to direct loudspeaker line arrays.
perceptual coding - A lossy digital audio data compression technique based on the human hearing mechanisms of masking and critical bands. AC-3 and AAC are examples of digital audio data compression schemes based on perceptual coding.
perfect pitch - The ability to name the pitch of a note, or to sing a named note, without reference to a previously sounded one. It is sometimes called 'perfect pitch.
Perfect-QTM graphic equalizer - Rane Corporation's trademark term for their true response graphic equalizer technology.
period - Abbr. T, t (1) The period of a periodic function is the smallest time interval over which the function repeats itself. (For example, the period of a sine wave is the amount of time, T, it takes for the waveform to pass through 360 degrees. Also, it is the reciprocal of the frequency itself: i.e., T = 1/f.) (2) a. The least interval in the range of the independent variable of a periodic function of a real variable in which all possible values of the dependent variable are assumed. b. A group of digits separated by commas in a written number. c. The number of digits that repeat in a repeating decimal. For example, 1/7 = 0.142857142857... has a six-digit period. [AHD]
periodic motion - Motion that repeats itself at regular or predictable intervals.
peripheral - Equipment physically independent of, but which may interface to a computer or a controller.
Perkins EQTM - - Trademark of Mackie for their mixing board EQ designed by the legendary Cal Perkins of Marantz, JBL & Fender fame.
permeability - A general term used to express various relationships between magnetic induction and magnetizing force. [IEEE]
permeance - A measure of the ability of a magnetic circuit to conduct magnetic flux; the reciprocal of reluctance. [AHD]
permittivity - Abbr. ε A measure of the ability of a material to resist the formation of an electric field within it.
personal monitors - A special earpiece or earplug containing high quality miniature loudspeaker systems, similar to hearing aids, used for on-stage and recording studio purposes in lieu of traditional floor foldback monitors.
PET (protective earth terminal) - Terminal connected to conductive parts of Class I equipment for safety purposes. This terminal is intended to be connected to an external earthing system by a PEC (protective earth conductor).
PFC (power-factor-corrected) - Power factor correction reduces phase error and improves wave shape in electrical sources and power supplies. The PFC circuitry acts to make the load appear more resistive. Power factor varies between zero and one in value. It is unity, or one, when it is purely restive. This is when the input current wave shape and phase exactly match the input voltage wave shape and phase. AC mains voltage is supposed to be sinusoidal, so a power factor of unity requires in-phase, sinusoidal current. Power factor correction is any passive or active measure taken to improve the phase relationship and/or harmonic content (shape) of current so that it matches the input voltage.
PFL (pre-fade listen) - A term used on recording consoles and mixers, referring to a signal taken before the main channel fader. The significance is this signal is not affected by the fader position. Normally used to monitor (via headphones) to an individual input (or a small group of inputs) without affecting the main outputs, particularly useful in that it allows listening to an input with its fader all the way down (off). In broadcast this function is often called cueing, while recording or live-sound users may also refer to it as soloing.
phantom power - Invented by Georg Neumann in 1966, the term given to the standardized scheme of providing power supply voltage to certain microphones using the same two lines as the balanced audio path. The international standard is IEC 60268-15, derived from the original German standard DIN 45 596.
phase - Audio signals are complex AC (alternating current) periodic phenomena expressed mathematically as phasors, or vectors. Phase refers to a particular value of t (time) for any periodic function, i.e. it is the relationship between a reference point and the fractional part of the period through which the signal has advanced relative to an arbitrary origin.
phase cancellation - When two signals have the same exact time relationship to each other, they are said to be "in-phase;" if they do not, they are said to be "out-of-phase." If two out-of-phase signals add together, since this is vector arithmetic, they will, in fact, subtract from one another. This is called phase cancellation.
phase delay - A phase-shifted sine wave appears displaced in time from the input waveform. This displacement is called phase delay and is usually constant for all frequencies of interest. Used as another name for group delay; however there are instances where they are not the same, for example systems exhibiting ripple in their phase vs. frequency characteristics.
phase lag and phase lead - Phase shift caused by reactive elements (capacitors and inductors) that either subtracts (lag) or adds (lead) degrees of shift.
phase linear - (1) Chiefly a European phrase meaning "linear phase." Any system which accurately preserves phase relationships between frequencies, i.e., that exhibits pure delay. (2) Consumer hi-fi company where the Rane owners worked before starting Rane Corporation.
phase lock loop - Abbr. PLL - A circuit for synchronizing a variable local oscillator with the phase of a transmitted signal. The circuit acts as a phase detector by comparing the frequency of a known oscillator with an incoming signal and then feeds back the output of the detector to keep the oscillator in phase with the incoming frequency. Commonly used for bit-synchronization.
phase plug - A device and technique that extends high frequency response by preventing cancellation of high frequency waves.
phaser - Also called a "phase shifter," this is an electronic device creating an effect similar to flanging, but not as pronounced.
phasor - (1) A complex number expressing the magnitude and phase of a time-varying quantity. It is math shorthand for complex numbers. Unless otherwise specified, it is used only within the context of steady-state alternating linear systems. [Example: 1.5 /27° is a phasor representing a vector with a magnitude of 1.5 and a phase angle of 27 degrees.]
phi - The symbol for the "Golden Rectangle" or "Golden Ratio." It is a never-ending, never-repeating number.
Phoenix-blocks (or -connectors or -strips) - A term, becoming generic, meaning disconnectable, or plugable terminal blocks, after Phoenix Contact connector company, although dozens of companies make them. Also called Euroblocks.
phon - A unit of apparent loudness, equal in number to the intensity in decibels of a 1,000 Hz tone judged to be as loud as the sound being measured.
phonautogram or phonautograph - An apparatus for automatically recording sound vibrations in the form of a tracing on a revolving cylinder. [OED]
phonetic - Representing the sounds of speech with a set of distinct symbols, each designating a single sound: phonetic spelling.
phonograph - (1) Literally means "writing sound", a term coined from Greek roots. (2) A machine that reproduces sound by means of a stylus in contact with a grooved rotating disk. [AHD]
phonograph cartridge (categories) - Piezoelectric (crystal/ceramic) cartridges, Magnetic cartridges, Strain-Gauge cartridges and Optical readout.
phonography - Literally "sound-writing," this term refers to field audio recordings used in music compositions. (1) The science or practice of transcribing speech by means of symbols representing elements of sound; phonetic transcription. (2) A system of shorthand based on phonetic transcription. [AHD]
phonology - (1) The study of speech sounds in language or a language with reference to their distribution and patterning and to tacit rules governing pronunciation. (2) The sound system of a language: the phonology of English. [AHD]
physics - A natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves. [Wikipedia]
pi - Symbol π (Greek lower-case pi) - (1) In reference to mathematics, a transcendental number, approximately 3.14159, represented by the Greek lower-case pi symbol, that expresses the ratio of the circumference to the diameter of a circle and appears as a constant in many mathematical expressions. [AHD] (2) In reference to Filters, equal to 180 degrees or integral multiples thereof.
pianoforte - Original Italian-derived name for the musical instrument now shortened to "piano."
picket fencing - The experience, in car audio FM systems, of static and signal weakening heard while slowing down and stopping; the signal comes and goes, weakens and distorts then clears.
pickup - A device that "picks up" sound and converts it into an electrical signal. Many technologies exist, from the most popular electromagnetic models (magnetic pickups) found on electric guitars to piezoelectric models seen on acoustic instruments and used in early phonograph cartridges (soon replaced with electromagnetic models using either moving magnet or moving coil technologies).
pickup patterns - A microphone's directionality or polar pattern indicates how sensitive it is to sounds arriving at different angles about its central axis.
pico- Prefix for one trillionth (10-12), abbreviated p
PICO (Program In, Chip Out) - Hewlett-Packard technology that use computers to design computers.
picofarad Abbr. pF - One trillionth (10-12) of a farad.
piezo - derived from the Greek piezein, which means to squeeze or press.
piezoelectric - the name given to a class of materials (dielectric crystals) that produce electricity or become polarized when mechanically strained or stressed. In pro audio used to create pickups, microphones and loudspeakers or buzzers, and in digital circuits quartz crystals for stable timing references.
pin-1 problem - Phrase created by Neil A. Muncy (Canadian electroacoustic system consultant; also see PSW Live Chat With Neil Muncy) to describe the improper connection of the "pin-1" terminal of XLR connectors found on analog pro audio equipment. The correct way to terminate pin-1 of XLR connectors is to bond it to the chassis immediately at the entry and exit points. It should not be connected to circuit signal ground. Equipment with pin-1 left open, or connected to circuit signal ground is said to suffer from a "pin-1 problem."
pinging - A technique for determining whether a specific IP address is accessible.
pin jack - (aka phono jack or pin jack) The Radio Corporation of America (RCA) originally developed this type of unbalanced pin connector for internal chassis connections in radios and televisions during the '30s.
pink noise - Pink noise is a random noise source characterized by a flat amplitude response per octave band of frequency (or any constant percentage bandwidth), i.e., it has equal energy, or constant power, per octave.
pinna - The outer portion of the ear; acts like an audio filter or equalizer and separates sounds coming from the front and rear. Also called auricle.
pipa - Chinese 4-string lute with 31 frets and a pear-shaped body.
pipe organ - An instrument consisting of a number of pipes that sound tones when supplied with air and a keyboard that operates a mechanism controlling the flow of air to the pipes.
pistonphone - A calibration device consisting of a chamber and moving diaphragm (piston) that creates a precise pressure at a specific frequency. The frequency is typically 250 Hz with a standard pressure of 120-125 dB SPL.
pitch - Frequency or tone of a sound.
pitch ribbon - A touch-sensitive strip used to vary pitch. The most popular design is a variable resistor shaped into a linear controller where the resistance is continuously variable from one end to another.
pitch-shifting or pitch-transposing - An effect that changes the pitch (frequency or tone) of musical notes without changing their length, or timing.
pivot and jewel - Consisting of a hardened pivot between two polished bearing surfaces.
pixel (picture element) - The smallest element on a display surface, like a video screen, that can be assigned independent characteristics.
PLA (programmable logic array) - A programmable logic device in which both the AND & OR arrays are programmable.
placement equalization or placement EQ - Term coined by Tomlinson Holman (of THX fame) to mean moving around the loudspeaker and listener until the room response (at the listener) is smoothest.
planar - (1) Of, relating to, or situated in a plane. (2) Flat: a planar surface. (3) Having a two-dimensional characteristic. [AHD]
PLASA - The lead body for those working in the live events, entertainment and communication industries worldwide; now merged with ESTA.
PLD (programmable logic device) - The generic name for an integrated circuit offering a vast array of logic function building blocks that the circuit designer defines (programs) to interconnect for specific applications.
plenum - (1) A ductwork system in which air is at a pressure greater than that of the outside atmosphere. (2) Such a system located in the space above a suspended ceiling, used to circulate air back to a building's HVAC.
plenum cable - The type of cable used when smoke retardant properties are required. Plenum cable is specifically designed for use in a plenum area (see above) which is typically used as the distribution system in buildings.
PLL (phase lock loop) - Abbr. PLL - A circuit for synchronizing a variable local oscillator with the phase of a transmitted signal. The circuit acts as a phase detector by comparing the frequency of a known oscillator with an incoming signal and then feeds back the output of the detector to keep the oscillator in phase with the incoming frequency. Commonly used for bit-synchronization.
plug - Common name for audio connectors, where plug = male is the standard convention for 1/4" and RCA only.
plugging - In reference to motors, the act of reversing the motor connections to develop a strong counter torque to decelerate.
plugin or plug-in - An accessory program that extends the capabilities of an existing application. Also called add-in or add-on. [AHD]
Plunkett, Donald J. - (b. 1924-2005) American recording engineer who was a founding member of the AES and its Executive Director for 20 years.
PM (personal monitors) - A special earpiece or earplug containing high quality miniature loudspeaker systems, similar to hearing aids, used for on-stage and recording studio purposes in lieu of traditional floor foldback monitors.
PMPO (peak music power output or peak momentary performance output) - An arbitrary made-up specification (marketing gimmick) that supposedly measures the total maximum power output from an amplifier at a given THD+N level during a brief transient. Also used to express dubious loudspeaker power ratings. Typically there is a 12-to-1 difference between PMPO and real apparent power (67:1 is the record).
PnP (plug 'n play) - (1) The technology that lets certain operation systems (Windows 95, others) automatically detect and configure most of the adapters and peripherals connected to or sitting inside a PC. (2) Any system with automatic detection and configuration of auxiliary devices.
PoE (Power over Ethernet) The name for the technology defined by IEEE 802.3afthat allows Ethernet appliances to receive power as well as data over existing LAN CAT 5 cabling.
polarity - A signal's electromechanical potential with respect to a reference potential.
polar response - microphone polar patterns (also called microphone directivity response):
· omnidirectional - A response pattern that is as close to a perfect sphere as possible, i.e., it is not directional at all, or is a non-directional microphone.
· cardioid - An on-axis response shaped like a cardioid with essentially no pickup to the rear.
· supercardioid - cardioid-shaped response that includes small pickup directly to the rear.
· hypercardioid - A cardioid-shaped response that includes greater rear pickup than the supercardioid design.
· subcardioid - A cardioid-shaped response that does not tuck-in or null at the rear, instead has a smooth flat response to the rear.
· figure-of-eight or bidirectional microphone - one that responds equally front and rear and not at all to side sounds.
· shotgun - The most directional response pattern, characterized by small sensitivity lobes on the left, right, and rear, with extreme sensitivity to the front.
poles - The roots of the denominator of a circuit transfer function, i.e., the values that make the denominator equal zero. Compare with zeros.
polyphonic - Two or more independent melodic parts sounded together. [AHD]
popcorn noise - Noise primarily found in integrated circuit audio amplifiers that exhibit a sizzling, frying hot-grease kind of sound, similar to popcorn popping. Found to be due to manufacturing defects in the form of metallic impurities in the junctions, often caused by dirty fabrication lines. The frequency spectrum typically conforms to 1/frequency-squared.
pop filter or popshield - A filter, usually made of acoustic foam material, put over a microphone to reduce wind noises and "pop" sounds from users.
poppysmic - Word for the sound made by smacking of the lips. Hit the link for more.
portamento - A smooth uninterrupted glide in passing from one tone to another, especially with the voice or a bowed stringed instrument. [AHD]
Portastudio® - Registered trademark name for TEAC's Model 144, the world's first 4-track cassette recorder introduced at the 1979 New York AES show.
Porter, Bill - (b. 1931-2010) American recording engineer who created hits with Chet Atkins, Roy Orbison, Everly Brothers and Elvis Presley to name only a few.
pot (lowercase) - Shortened form of potentiometer.
potential difference - The amount of energy per unit charge needed to move a charged particle from a reference point to a designated point in a static electric field; voltage. Also called potential. [AHD]
potentiometer - A three-terminal variable resistor. Two terminals connect to the ends of the resistor, while the third terminal is attached to a movable device that makes contact with the resistive element. The movable terminal, or slider, is capable of being positioned from one end of the element to the other. Many physical arrangements exist, with the rotary design being the most common, followed by linear motion (used in graphic equalizers, for example), all the way to tiny SMT devices. Often used as voltage dividers in electronic circuits, the input voltage is applied to the top of the resistive element, while the other end is tied to ground or a common reference and the output is taken from the slider. When the slider is positioned to the top extreme, the output equals the input, or the entire voltage; moving it to the bottom extreme gives an output of zero volts; and every possible level between is available as the slider is moved from one end to the other. The most common application uses this arrangement to control the volume of an audio device. In this manner the voltage, or electrical potential is varied, hence, a potentiometer. The taper of the pot controls the rate at which the voltage changes as the slider is moved. The taper defines the amount of resistive change as a function of travel. Several popular examples follow:
· audio taper (aka A-taper): Usually 15% resistance at the 50% rotation point.
· E-taper: Similar to a reversed audio taper but with 25% resistance at the 50% rotation point.
· linear taper (aka B-taper): Always 50% resistance at the 50% travel point.
· log taper (aka D-taper): Often used as an audio taper since its 50% rotation point has 10% resistance.
· MN taper (aka balance pot) Special taper developed for home stereo "Balance" controls. Consists of two sections (one for each channel) operating opposite each other. Exactly one-half of each section is a zero resistance surface (i.e., solid-copper or equivalent), the next 50% of travel is linear taper. Therefore for one channel rotating the slider through the first 50% of travel does not change the level at all, while the other channel is reduce from full to zero, and vice versa, with the middle position (usually featuring a center-detent) always passing full signal to each channel. See balance control.
· RD-taper: A reversed D-taper (see log taper above).
POTS (uppercase) (plain old telephone system). - The normal single line basic telephone service. Often used in reference to modems associated with regular telephone lines.
power - (1) a. In reference to Electronics, the product of applied voltage (potential difference) and current in a direct-current circuit (or the voltage squared divided by the resistance, or the current squared times the resistance). b. The product of the effective values of the voltage and current with the cosine of the phase angle (between current and voltage) in an alternating-current circuit. (2) In reference to Physics, rate at which work is done, expressed as the amount of work per unit time, and measured in units such as the watt (1 joule per second, which equals the power dissipated (as heat) by 1 ohm of resistance when 1 ampere of current passes through it) and horsepower (equal to 745.7 watts). [AHD]
power amplifier - An electronic device used to increase an electrical signal. The signal may be voltage, current or both (power).
power amplifier dummy load - Modeling a real world loudspeaker for power amplifier testing purposes has been studied for years, resulting in many circuit possibilities.
power amplifier sensitivity - The input level required to produce one watt output into a specified load impedance, usually 4 or 8 ohms. [EIA-490]
power compression - The phenomena where the power transfer from the amplifier to the loudspeaker decreases as the loudspeaker voice coil heats up. As the voice coil heats its resistance increases reducing the resulting power for the same applied voltage. Typical compression numbers run from 3 dB to 6 dB.
power equations - It was James Prescott Joule who came up with (and published in 1841) the basic power equations P = I2R; P = IE; & P = E2/R, NOT Georg Simon Ohm as is commonly believed. Contrast with Ohm's Law.
power factor - Abbr. PF The ratio of the total (or real) power in watts (resistive load; aka real power) to the total apparent power in voltamperes (VA) (reactive load).
power-factor-corrected (PFC) - Power factor correction reduces phase error and improves wave shape in electrical sources and power supplies. The PFC circuitry acts to make the load appear more resistive. Power factor varies between zero and one in value. It is unity, or one, when it is purely restive. This is when the input current wave shape and phase exactly match the input voltage wave shape and phase. AC mains voltage is supposed to be sinusoidal, so a power factor of unity requires in-phase, sinusoidal current. Power factor correction is any passive or active measure taken to improve the phase relationship and/or harmonic content (shape) of current so that it matches the input voltage.
Power over Ethernet (PoE) - The name for the technology defined by IEEE 802.3af that allows Ethernet appliances to receive power as well as data over existing LAN CAT 5 cabling.
PowerPC - A super powerful RISC processor PC jointly developed by IBM, Apple and Motorola, designed to run any PC operating system (MS-DOS, UNIX, Windows, OS/2, Mac OS. etc.). Featured in Apple's line of "PowerMac" computers.
power spectral density - measured in a time interval less than one second. Term used to specify UWB radios.
power supply rejection ratio - A measure of a circuit's immunity to power supply noise and variations.
ppm (lowercase) (parts per million) - Indicates one part in 106, with a value of 1 × 10-6.
PPM (uppercase) (peak program meter) - An audio meter originally developed in Europe to accurately measure and display peak audio signals (as opposed to average audio signals).
Pramanik stylus - A ultra-lightweight 4-channel phono cartridge with a Beryllium cantilever and a multifaceted stylus invented by Subir "Pram" Pramanik of Bang & Olufsen in 1973.
Prandtl number (Pr) - the ratio of the molecular diffusion coefficients of momentum in terms of heat, i.e., a property of air.
preamplifier - name applied to the first amplifier in the audio chain, accepting inputs from microphones, or other transducers, and low output sources (CD players, tape recorders, turntables, etc.). The preamplifier increases the input signals from mic-level, for instance, to line-level.
pre-preamplifier - (1) A very low noise, high gain audio preamp used to boost signal levels from very low sources such as moving coil phono cartridges, some acoustic pick-ups, etc.
precedence effect - describes the human psychoacoustic phenomena of correctly identifying the direction of a sound source heard in both ears but arriving at different times.
pre-emphasis - A high-frequency boost used during recording, followed by de-emphasis during playback, designed to improve signal-to-noise performance.
presence control - A control often seen on guitar amplifiers (and occasionally on hi-fi preamplifiers) used to boost high frequencies to make the sound brighter.
pressure gradient microphone - If both the front and rear of a diaphragm are exposed to a sound field, then the force that vibrates the diaphragm results from the difference between the sound pressures in front and to the rear of the diaphragm (called the pressure gradient). The magnitude of the driving force depends on the distance between the front and rear sound entries, the frequency, and the angle of incidence and is therefore a directional variable which can be utilized to design directional microphones. Cardioid, figure 8, or hypercardioid polar patterns can be achieved by incorporating appropriate sound paths. [From AKG Acoustics Glossary]
pressure zone microphone (PZM) - Patented by Ed Long & Ron Wickersham in 1982, a technique and design where the microphone is mounted on a flat plate which acts as a reflective surface directing sound into the mic capsule. The PZM principle uses the compression and decompression of air between the plate and the membrane in parallel with the plate (the gap is very narrow, typically only a millimeter or less. This arrangement gives about 6 dB extra amplification of the signal, which means 6 dB less inherent electronic noise.
pretzel - A French horn. [Decharne]
print-through - The name for the magnetic tape recording phenomena where the act of layering, or winding layer upon layer of tape causes the flux from one layer to magnetize the adjacent layer, thus printing through from one layer onto another layer. Also called crosstalk or interlayer transfer.
printed circuit board (PCB) - An electric circuit in which the conducting connections have been printed or otherwise deposited in predetermined patterns on an insulating base. [AHD]
Pritts, Roy - (b. 1937-2007) American musician and recording engineer who founded the Music Technology/Recording Arts program at the University of Colorado in 1971.
probability density function, or pdf, or p.d.f. - The name given to a mathematical function that defines a continuous interval (i.e., one without gaps), or curve, such that the area under the curve (and above the x-axis, i.e., the probability is always positive) described by the function is unity, or equals one, or 100%.
proceleration "The acceleration of acceleration." [A Dictionary of the Near Future by Douglas Coupland, NY Times, September 12, 2010.]
Programming, Law of - The law states that every program contains at least one bug. The law further states that every program can be shortened by at least one instruction. Therefore, the law concludes, every program can be reduced to one instruction that does not work.
progressive array - a straight flat line array that gradually creates an arc at the lower end, forming the letter "J" like shape.
PROM (programmable read-only memory) - A memory device whose contents can be electrically programmed (once) by the designer.
propagation - The motion of waves through or along a medium. For electromagnetic waves, propagation may occur in a vacuum as well as in material media.
propagation delay - The initial delay through a signal processing box, i.e., the time it takes for a signal to pass once through a device.
proportional-Q graphic equalizer (also variable-Q) - Term applied to graphic and rotary equalizers describing bandwidth behavior as a function of boost/cut levels. The term "proportional-Q" is preferred as being more accurate and less ambiguous than "variable-Q." If nothing else, "variable-Q" suggests the unit allows the user to vary (set) the Q, when no such controls exist. The bandwidth varies inversely proportional to boost (or cut) amounts, being very wide for small boost/cut levels and becoming very narrow for large boost/cut levels. The skirts, however, remain constant for all boost/cut levels.
prosumer - Shortened form of professional + consumer, often used to refer to home recording studio equipment.
protocol - A specific set of rules, procedures or conventions relating to format and timing of data transmission between two devices. A standard procedure that two data devices must accept and use to be able to understand each other.
proximity effect - Term for the increase in low frequency response (bass boost), or sensitivity, of most directional microphones when the sound source is within a few inches.
PSD (power spectral density) - A measure of how the power in a signal changes over frequency. It is the total power in a specified bandwidth divided by the specified bandwidth expressed in watts per hertz or dBm per hertz.
pseudo-balanced output - A two-wire (with overall shield) interfacing technique for an unbalanced output where a resistor equal to the output resistor is placed in series with the return leg (either pin-3 for an XLR connector or the ring lead for an 1/4" TRS connector). This makes both lines measure the same impedance when looking back from the receiver and allows the common-mode rejection feature of the input differential amplifier to function.
PSPICE (Personal SPICE) - Developed in 1984 by Wolfram Blume (first doing business as Blume Engineering, then MicroSim, acquired by OrCAD, now owned by Cadence), the first version of SPICE for personal computers, is now the industry standard for circuit-simulation.
Psophometric weighting - refers to any weighting curve used in the measurement of noise. In the field of audio engineering it has a more specific meaning, referring to noise weightings used especially in measuring noise on telecommunications circuits. [Wikipedia]
PSRR (power supply rejection ratio) - In the most general sense, a measure of a circuit's immunity to power supply noise and variations.
psychoacoustics - The scientific study of the perception of sound.
public address (PA) - an electronic amplification system with a mixer, amplifier and loudspeakers, used to reinforce a sound source.
PUFF - Popular microwave circuit simulation program for laying out and analyzing microstrip and stripline circuits on IBM-compatible personal computers.
pumping - Loud level variations caused by quick noticeable variations of level associated by use of heavy compression or limiting.
punch-in/punch-out - To engage/disengage record mode on a track previously recorded, usually for purposes of correcting unwanted segments.
Pupin, Michael I. - (b. 1858-1935) Serbian-American physicist who invented the Pupin coil (a special inductor) that greatly extended the range of long-distance telephone communication by adding inductance. These coils were placed at predetermined intervals along the transmitting wire (a process known as pupinization).
PURLnet - A low-cost, low-power, two-way, wireless communications standard between compliant devices anywhere in and around the home (automation, toys, PC peripherals, etc.), developed by Philips and others. Claiming lower cost, lower power consumption, higher density of nodes per network and simplicity of protocols, it is an alternative to Bluetooth.
purple (or violet) noise - +6 dB/oct increasing noise density (power proportional to frequency-squared; most amount of high frequency energy or power).
PVC cable (polyvinyl chloride) - The most common type of cable used when smoke retardant properties are not required. PVC is a tough water and flame retardant material, but is not smoke retardant. If PVC catches fire, it emits noxious gases, and if the cable is run in a plenum area, the deadly gases can be dispersed throughout the building.
PVDF (polyvinylidene fluoride) - A type of plastic exhibiting piezo-electric properties, used by Dr. Koh Seok-keun, P&I (Plasma & Ionbeam) Corporation, to produce a thin-membrane midrange/tweeter driver. The result is claimed to produce a near perfect vertical or horizontal radiation pattern.
PWM (pulse width modulation) - A conversion method in which the widths of pulses in a pulse train represent the analog information.
Pythagorean temperament -The mathematical principles of musical harmony according to the Greek philosopher Pythagoras.
PZM (pressure zone microphone) - Patented by Ed Long & Ron Wickersham in 1982, a technique and design where the microphone is mounted on a flat plate which acts as a reflective surface directing sound into the mic capsule. The PZM principle uses the compression and decompression of air between the plate and the membrane in parallel with the plate (the gap is very narrow, typically only a millimeter or less. This arrangement gives about 6 dB extra amplification of the signal, which means 6 dB less inherent electronic noise. Now owned by Crown International, a Harman International Company.
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