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Dictionary of Audio Terminology - N

N (newton) - The International System unit of force. It is equal to the force required to accelerate a mass of one kilogram one meter per second per second.

NAB (National Association of Broadcasters) A professional trade organization for people working in the radio and television industry.

NACFM (National Association of Church Facility Managers) "A non-profit organization established in 1995 to promote networking and educational advancement opportunities for Facilities Management Professionals. NACFM provides an informational resource for church and religious facility management professionals by discussion groups, forums, panels, lectures, seminars, or similar programs or activities (such as this web site) designed to fulfill the purposes of the organization."

NAG (needed acoustic gain) - The gain in decibels required by sound reinforcement to achieve an equivalent acoustic level at the farthest listener equal to what the nearest listener would hear without sound reinforcement.

Nagra - Famous Swiss company whose field tape recorders became the standard for all professionals.

NAH (nearfield acoustic holography) - A sound radiation measurement system developed by Professors J. D. Maynard, E. G. Williams, and Y. Lee at the Pennsylvania State University, Department of Physics in 1985.

NAMA - Native American Music Awards.

NAMM (National Association of Music Merchants) - A professional trade organization for people working in the music business -- primarily in retailing and manufacturing of music making products.

NAMMYS - The name of the award given yearly by NAMA (Native American Music Awards).

nano- Abbr. N - A prefix for one billionth (10-9).

nanosecond - Abbr. Ns - One billionth (10-9) of a second.

nanotechnology - The science and technology of building electronic circuits and devices from single atoms and molecules.

nanoweber - Abbr. nWb - A unit of magnetic flux equal to one billionth (10-9) of a weber.

Napier, John - (1550-1617) Scottish mathematician who invented logarithms and introduced the use of the decimal point in writing numbers. [AHD]

Napier's bones - A set of graduated rods used to perform multiplication quickly. Lord Napier is credited with creating them to expedite arithmetical calculations. [Kacirk]

NAPRS (Nashville Association of Professional Recording Services) - Established in 1995 to promote Nashville's finest recording studios, services and engineers worldwide; dissolved in 2009.

NARAS - National Academy of Recording Arts & Science.

NARM (National Association of Recording Merchandisers) - An industry organization made up primarily of music retailers acting as an advocate body for the common interests of merchandisers and distributors of music to industry and public policy makers.

narrow-band filter - Term popularized by equalizer pioneer C.P. Boner to describe his patented (tapped toroidal inductor) passive notch filters.

National Electrical Code - The name for the United States electrical safety standard (NFPA-70).

National Music Museum - Located in Vermillion, S. Dakota on the Campus of The University of South Dakota, it has more than 13,500 items in its collection (largest in the world) with some 800 on display at any one time.

National Recording Registry - Set up by Congress in 2002 to preserve historical recordings.

natural logarithm - A logarithm based on the powers of e (aka Base-e).

N curve (normal curve) - The name of the standard mono optical track that has been around since the beginning of sound for film.

NC (noise criterion) curves - A unit of measurement for the ambient or background noise level of occupied indoor spaces, i.e., a measure of its noisiness -- true story; real word.

near-end crosstalk - Crosstalk that is propagated in a disturbed channel in the direction opposite to the direction of propagation of the signal in the disturbing channel. The terminals of the disturbed channel, at which the near-end crosstalk is present, and the energized terminal of the disturbing channel, are usually near each other. [IEEE Std 802.5]

near field or near sound field - The sound field very close to the sound source, between the source and the far field.

near-field monitor - A loudspeaker used at a distance of 3-4 feet (1-1½ meters) in recording studios.

NEC (National Electrical Code) - The name for the United States electrical safety standard (NFPA-70).

negative - An excess of electrons in a conductor or semiconductor.

negative feedback - The act of comparing a fraction of the output signal to the input signal at the input to an amplifier in such a way that the amplifier will keep this fraction of the output signal always exactly the same as the input signal.

negative logic - An electronic logic system where the voltage representing one, active, or true has a more negative value than the voltage representing zero, inactive, or false. [IEEE Std 1451.2]

negative resistor (aka negistor) - A resistor having the opposite characteristics of Ohm's Law, i.e., the current goes down if the voltage goes up and vice versa.

Negistor - A resistor having the opposite characteristics of Ohm's Law, i.e., the current goes down if the voltage goes up and vice versa.

neodymium - Abbr. Nd - Popular rare-earth metal used to make superior magnets for loudspeakers and microphones. Neodymium iron boron magnets have a more linear frequency response, are more powerful and smaller, with higher output levels than conventional iron magnets.

neodymium motors - Generic name for a new class of ironless electric motors that do not use iron or ferrite permanent magnets in their construction. Instead they use anisotropic NdFeB (neodymium-iron-boran) bonded magnets (aka neodymium magnets). Of interest to pro audio users since experimental loudspeakers based on bonded magnets are being researched as not only lighter and more eco-friendly but produce audio with lower distortion.

nephew node - A node with one port in standby and all other ports (if any) disabled, disconnected, or suspended. The peer uncle node proxies for the nephew node during bus resets. [IEEE Std 1394b]

network Generally used to mean a multi-computer system (as opposed to a single computer bus-type system) where multiple access is allowed from more than one computer at a time. Characterized by full two-way (duplex) communications between all equipment and computers on the network.

Neumann, Georg - (1891-1976) German inventor, entrepreneur and audio industry pioneer of high-quality microphones.

neutral - (1) Having no electrical charge. (2) Common point of a star-connected generator or transformer winding. [IEEE Std 1020]

Neve 1073 Console Module - Designed by Rubert Neve in 1970, this mic-preamp with 3-band EQ set the standard for all mic channels to follow.

Neville Thiele MethodTM Crossover Filter - Trademarked term for the patented technology developed by Neville Thiele for Whise Acoustics in Australia. Two choices are offered, a 4th-order with rolloff slopes of 36 dB/octave and an 8th-order with 52 dB/octave slopes. The published curves resemble 4th- and 8th-order cascaded elliptic filters.

newton - Abbr. N - The International System unit of force. It is equal to the force required to accelerate a mass of one kilogram one meter per second per second.

Newton, Sir Isaac - (1642-1727) English mathematician and scientist who invented differential calculus and formulated the theory of universal gravitation, a theory about the nature of light, and three laws of motion. The sight of a falling apple supposedly inspired his treatise on gravitation, presented in Principia Mathematica (1687). [AHD]

NEXT (near-end crosstalk) - Category wiring. Interference between signals on twisted pair cable caused by damage (usually a loosening of the tight twist required for high speed transmission) occurring close to the connector.

ney Musical - A Turkish end-blown flute.

ngoni - A West African stringed instrument.

nibble - A group of four bits or half a byte (8-bits). Also called a quartet.

NIC (network interface card) - The PC expansion board that connects a device to a LAN, usually Ethernet-based.

Nichols, Roger - (b. 1944-2011) American recording engineer most famous for his innovative and Grammy Award-winning work with Steely Dan.

nickelodeon - (1) An early movie theater charging an admission price of five cents. (2) A player piano. (3) A jukebox. [AHD]

NIME (New Interfaces for Musical Expression) - International organization for the development of new musical interface design.

Nipper - The famous "His Master's Voice" RCA dog. A bull terrier and fox terrier mix born in 1884 and named for his propensity to nip at peoples' legs.

NIST (National Institute of Standards and Technology) Government organization who produces (among vastly other things) Special Publication 811: Guide for the Use of the International System of Units (SI), the authority on this subject.

Nixie tube - A numerical read-out cold-cathode tube first developed by Haydu Brothers Laboratories in 1955, later purchased by Burroughs Corporation who registered the name. The name Nixie was derived by Burroughs from "NIX I", an abbreviation of "Numeric Indicator eXperimental No. 1."

No also Noh - The classical drama of Japan, with music and dance performed in a highly stylized manner by elaborately dressed performers on an almost bare stage. [AHD]

node - A point of minimum amplitude in a one-dimensional standing wave field. A nodal line is a line of minimum amplitude in a two-dimensional filed, and a nodal surface is a surface of minimum amplitude in a three-dimensional field. [Morfey]

node - In reference to electronics, a point of interconnection between two or more components. In reference to physics, a point or region of virtually zero amplitude in a periodic system.

noise - Sound or a sound that is loud, unpleasant, unexpected, or undesired. In reference to physics, a disturbance, especially a random and persistent disturbance, that obscures or reduces the clarity of a signal. In reference to computer science Irrelevant or meaningless data. From Latin meaning nausea, discomfort and seasickness. [AHD]

noise cancelling headphones - Special headphones incorporating a microphone built into the headset that samples the ambient sound and adds it back out-of-phase to the headphone signal.

noise cancelling microphone - A special dynamic microphone designed so both sides of the diaphragm are exposed to the sound field. Close direct sound strikes primarily one side of the diaphragm causing it to move while sounds from far away tend to be canceled because they strike the diaphragm from all sides with no net force.

noise color - People working in pro audio know the terms white noise and pink noise, but few recognize the terms "azure noise" or "red noise," but they are real terms. Noise that is not white is called colored noise and will have more energy at some frequencies than others, analogous to colored light. White noise and pink noise are well defined and known; much less so are the others. White noise is so named because it is analogous to white light in that it contains all audible frequencies distributed uniformly throughout the spectrum. Passing white light through a prism (a form of filtering) breaks it down into a range of colors. Examination shows that red light is characterized by the longer wavelengths of light, i.e., the lower frequency region. Similarly, "pink noise" has higher energy in the low frequencies, hence the somewhat tongue-in-cheek term. The Federal Standard 1037C Telecommunications: Glossary of Telecommunication Terms defines four noise colors (white, pink, blue & black) and is considered the official source. No official standard could be found for the others.

The following list of noise colors is loosely based on a rainbow-prism light analogy, where a prism creates a rainbow effect by separating white light passed through it into a visible spectrum labeled red, orange, yellow, green, blue, indigo, and violet from lowest to highest frequencies. Also shown is the approximate slope of the power density spectrum relative to white noise used as the reference:

red noise also called brown noise or Brownian noise after Robert Brown: -6 dB/oct decreasing density (most amount of low frequency energy or power; used in oceanography; power proportional to 1/frequency-squared); popcorn noise.

pink noise: -3 dB/oct decreasing noise density (but, equal power per octave; 1/f noise or flicker noise; power proportional to 1/frequency).

white noise: 0 dB/oct reference noise with equal power density (equal power per hertz; Johnson noise).

grey noise: A random pink noise within the audible frequency range subjected to inverted A-weighting loudness curve per IEC 61672. It gives the listener the perception that it is equally loud at all frequencies.

blue (or azure) noise: +3 dB/oct increasing noise density (power proportional to frequency).

purple (or violet) noise: +6 dB/oct increasing noise density (power proportional to frequency-squared; most amount of high frequency energy or power).

black noise: silence (zero power density with a few random spikes allowed).

Other noise colors exist for specialized fields like video/photographic/image processing, communications, mathematical chaos theory, etc., but are not found in pro audio circles.

noise criterion (NC) curves - A unit of measurement for the ambient or background noise level of occupied indoor spaces, i.e., a measure of its noisiness -- true story; real word.

noise dose or noise exposure - Limits of noise exposure published by OSHA (US Department of Labor, Occupational Safety and Health Administration). It is a expressed as A-weighted SPL (dBA) term.

noise figure - The ratio between the Johnson noise (or thermal noise) of the equivalent input resistance of a circuit and its measured noise, expressed in decibels. It is the ratio of the output noise to the input noise, so the answer is always positive, with a theoretically noise-free device having a noise figure of 0 dB.

noise floor - Normally the lowest threshold of useful signal level, i.e., the residual noise with no signal present (although sometimes audible signals below the noise floor can be recovered).

noise gate - An expander with a fixed "infinite" downward expansion ratio. Used extensively for controlling unwanted noise, such as preventing "open" microphones and "hot" instrument pick-ups from introducing extraneous sounds into the system. When the incoming audio signal drops below the user set-point (the threshold point) the expander prevents any further output by reducing the gain to "zero."

NoiseMap™ - Trademark of Serato Audio Research for their proprietary technology used in the Scratch Live vinyl emulation system.

noise masking - The practice of adding white noise to an audio system to make background sounds unintelligible or less distracting; makes use of the human hearing masking phenomenon.

noise measurement filters - Special filters used in measuring loudness levels, and consequently carried over into audio noise measurements of equipment.

noise reduction Abbr. NR - A signal processing function used to reduce the amount of background noise.

noise shaping - A technique used in oversampling low-bit converters and other quantizers to shift (shape) the frequency range of quantizing error (noise and distortion).

NOM (number of open mics) - An acronym believed first created in 1967, or 1968, by Bill Snow after he retired from Bell Labs and went to work at Altec Lansing Research.

nominal - Insignificantly small; trifling: a nominal amount. It can also mean "according to plan or design." [AHD]

NOMM (number of open mics & mixers) - A term created by Rane Corporation extending the concept of NOM (above) to include multiple mixers as well as microphones.

nomogram – (1) A graph consisting of three coplanar curves, each graduated for a different variable so that a straight line cutting all three curves intersects the related values of each variable. (2) A chart representing numerical relationships. [AHD]

non-acoustic voice sensor - A device that can detect a person's voice without the person actually speaking out loud.

nonlinear - The amplitude of the output is not linearly proportional to the input. If a true sine wave were transmitted through a nonlinear device, its shape would be changed. [IEEE] Contrast with linear.

nonlinear distortion - Introduction of frequency components not present in the original signal. Contrast with linear distortion.

nonvolatile - Refers to a memory device that does not lose its data when power is removed from the system.

noratorA two-terminal circuit element with a voltage-current (V-I) characteristic curve consisting of all points on the V-I plane (except zero/zero because that is a nullator). The device does not define either the voltage or the current. Used to model complex circuits for analysis.

normal distribution - A theoretical frequency distribution for a set of variable data, usually represented by a bell-shaped curve symmetrical about the mean. [AHD]

normalize - The process of linearly increasing all digital samples by the same amount so that the largest original sample reaches a given level.

normalling jacks – Normalling, in reference to patchbay wiring design, is a wiring scheme where a signal path is established from one audio device to another without the use of a patch cord rather through the wiring of the “normalled jacks”.

Norteño - A genre of Mexican music.

Norton's Theorem - In simple terms, states that a complex linear circuit (i.e., no exponents or roots in its defining equations) can be replaced by a single current source and a parallel resistor.

Norton, Edward Lawry - (b. 1898-1983) American engineer who formulated Norton's Theorem while working at Bell Labs.

notch filter - A special type of cut-only equalizer used to attenuate a narrow band of frequencies.

note value - Indicates the relative duration of a note, using the color or shape of the note head, the presence or absence of a stem, and the presence or absence of flags/beams/hooks/tails. [Wikipedia]

NOTS (NATO off-the-shelf or niche off-the-shelf) - Government procurement term. Most often referencing software but general use is found. Compare with COTS, MOTS and GOTS.

Novachord - The name for Hammond's first commercially available synthesizer released in 1938.

noy - A subjective unit of noisiness.

NPO - Temperature coefficient designator meaning negative-positive-zero, i.e., the capacitance drifts negative and positive averaging zero. A marking meaning stable with temperature.

NR (noise reduction) - A signal processing function used to reduce the amount of background noise.

NRE (non-recurring engineering charge) - A one-time engineering charge for product development, separate from royalty or licensing fees.

NRZ (non-return to zero) - A system of binary code where one's are usually represented by a positive voltage and zeroes by a negative number, i.e., neither is ever zero volts.

NSCA (National Systems Contractors Association) - "Founded in 1980 as the National Sound Contractors Association, the NSCA underwent a name change in 1994 to better reflect the diversification found within the hi-tech industry of electronic systems.

NSP (native signal processing) - Intel-designed method of using a powerful microprocessor (like their Pentium CPU) for signal processing functions normally done by separate DSP chips.

NSSP (National Standards Systems Network) - A Web-based service launched by ANSI, along with government and industry partners. A full search & sales service provides for locating and buying virtually any standard.

NTMTM Crossover Filter (Neville Thiele MethodTM Crossover Filter) - Trademarked term for the patented technology developed by Neville Thiele for Whise Acoustics in Australia.

NTSC (National Television Standards Committee) - The United States and Japan standard for color formatting for television transmission developed in the 1950s. Compare with PAL/SECAM.

null - In reference to mathematics, of or relating to a set having no members or to zero magnitude. In reference to Instrumentation, a reading of zero. [AHD

] nullator - A two-terminal circuit element with a voltage-current (V-I) characteristic curve consisting of only the origin point on the V-I plane, i.e., it always has a value of 0-0. Used to model complex circuits for analysis.

null modem cable - Special wiring of an RS-232 cable such that a computer can talk to another computer without a modem (thus "null" modem).

nullor - A four-terminal circuit element consisting of a norator and a nullator; together they model an ideal op amp, i.e., one whose input voltage and current equal zero and whose output voltage and current can be any value.

numerator - The top part of a common fraction.

nu metal - A very diverse category that is somewhat based on heavy metal genre.

Nusselt number (Nu) - The coefficient of heat transfer.

nWb (nanoweber) - A unit of magnetic flux equal to one billionth (10-9) of a weber.

nyckelharpa - A Swedish keyed stringed instrument.

Nyquist diagram - For feedback circuits, the plot, in rectangular coordinates, of the real and imaginary parts of the open loop transfer function.

Nyquist frequency - The highest frequency that may be accurately sampled. The Nyquist frequency is one-half the sampling frequency.

Nyquist, Harry - (b. 1889-1976) Swedish born American physicist most famous in pro audio for his diagram and frequency developments.

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HistoryOfRecording.com acknowledges the Elsevier, Inc. publication, Audio Engineering know it all, the University of Washington Press publication, The Audio Dictionary, second edition, the Howard W. Sames & Co., Inc. publication, Audio cyclopedia, the Cambridge University Press publication, The Art of Electronics, Rane Corporation (Dennis A. Bohn, CTO), Houghton Mifflin Company publication, The American Heritage Dictionary of the English Language, Fourth Edition, the IEEE publication, IEEE 100: The Authoritative Dictionary of IEEE Standards Terms, Seventh Edition and Wikipedia in the preparation of this Dictionary of Audio Terminology.

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