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Natural Frequency The frequency of vibration or oscillation which a system (anything from a road bridge to an violin string) will inherently adopt according to its structure given a suitable excitation, such as a gale force wind or a bow. Also called the normal mode.

Near Field / Close Field: - The area which is close to the source. If we take a mic and place it right up against a sound source, we will be picking up it's sounds as they are in the near field, and if we take the microphone and place it far away from the sound source, we would be picking up the sounds (so long as it isn't too far away!) as they are in the WIDE field. Most commonly used to describe small loudspeakers which are designed to sound at their best a metre or two away from the listeners ear, hence lessening (but not eliminating the effects) of sound radiation in an acoustically imperfect room. NEAR FIELD: Some people prefer the term 'close field', to describe a loudspeaker system designed to be used close to the listener. The advantage is that the listener hears more of the direct sound from the speakers and less of the reflected sound from the room.

Net Shipments: The amount of manufacturer unit shipments after returns.

Noise A word used to describe signals which humans consider to contain little useful information, or which they actually find unpleasant.

Noise Floor: - Amount of background noise produced by a piece of audio hardware, measured in dB's.

Noise Gating"(cutting the signal for very short periods of time when it falls below a certain level - useful as a form of noise reduction and occaisionally as an effect in itself).

NOISE REDUCTION: System for reducing analogue tape noise or for reducing the level of hiss present in a recording.

NOISE SHAPING: A system for creating digital dither such that any added noise is shifted into those parts of the audio spectrum where the human ear is least sensitive. An audio tool for creating digital dither allowing added noise to be shifted into those parts of the audio spectrum where the human ear is least sensitive. See Dithering.

Non Linear Recording / Editing: - An advantage of the way digital data is stored / retreived (as separate "bits" of information, is that these bits of information can (in theory) be accessed and manipulated in any order (Random Access). In terms of digital audio and video this means that recorded material may be accessed and edited easily in a random, or non linear way, without physical manipulation of a medium such as tape (rewinding, splicing etc).

NON REGISTERED PARAMETER NUMBER: An addition to the basic MIDI spec that allows Controllers 98 and 99 to be used to control non-standard parameters relating to particular models of synthesizer. This is an alternative to using System Exclusive data to achieve the same ends, though NRPNs tend to be used mainly by Yamaha and Roland instruments.

NON-LINEAR RECORDING: Describes digital recording systems that allow any parts of the recording to be played back in any order with no gaps. Conventional tape is referred to as linear, because the material can only play back in the order in which it was recorded. Describes digital recording systems that allow any parts of the recording to be played back in any order with no gaps. Conventional tape is referred to as linear, because the material can only play back in the order in which it was recorded.

Normalise / Normalised / Normalled: - To boost the amplitude of a digital sound so that it is as high as it can be without clipping (0 dB). This is done by taking the highest level, then adjusting the rest of the signal accordingly. A socket is said to be normalised when it is wired such that the original signal path is maintained unless a plug is inserted into the socket. The most common examples of normalised connectors are the insert points on a mixing console.

Normalised / Normalled Connection: - A connection which lets a signal pass through it when no plug is inserted in it, but breaks the connection when a plug IS plugged into it. Most commonly found in "Jack" form (in the U.S. this connection is known as a "break-jack") in mixing desks and patchbays.

Normalization: An automatic process available in most audio software whereby the gain of all program material is adjusted so the peak level will just arrive at 0db. This can sometimes cause noise to enter into the recording if the recording levels are too low. There are many software programs such as BIAS’s Deck for OS X that allow normalization to very quickly correct an audio file that has been recorded at improper levels.

normalizing - the process of making audio files the same volume

Notation Software: A computer program, capable of displaying and printing MIDI information as standard musical notation. Although sequencers can include notation capability, they lack the sophistication of true notation programs which often have scanning capabilities allowing quick input of music for transposing to another key.

NOTE ON COMMANDS - a channel voice message that indicates a note is to begin sounding. Contains two additional data bytes: Note number and Note velocity.

Null Point: - See "Zero Crossing Point".

NUT: Slotted plastic or bone component at the headstock end of a guitar neck used to guide the strings over the fingerboard, and to space the strings above the frets. (Alt: all members of SOS staff!)

NYQUIST FREQUENCY - the highest frequency that any given digital audio system can capture. Defined as one half the sampling rate of that system. The highest frequency that can be reproduced accurately when a signal is digitally encoded at a given sample rate. The theory being, Nyquist frequency is half of the sampling rate. As in, when a digital recording uses a sampling rate of 44.1kHz, the Nyquist frequency is 22.050kHz. If a signal being sampled contains frequency components that are above the Nyquist limit, aliasing will be introduced in the digital representation of the signal unless those frequencies are filtered out prior to digital encoding. Theorem which deals with the digital audio problem of "Aliasing". The Nyquist theorem proves that the highest frequency recordable through digital sampling technology (without the horrible distortion caused by aliasing) will be half that of the sampling rate used. In practice, the sampling rate used should be @10% more than double. This is due to the fact that the Anti Aliasing filters used in the Analogue to Digital conversion process, despite having a very sharp roll off, do not reach their 0dB cutoff points until they are @10% higher also. The rule which states that a digital sampling system must have a sample rate at least twice as high as that of the highest frequency being sampled in order to avoid aliasing. Because anti-aliasing filters aren't perfect, the sampling frequency has usually to be made more than twice that of the maximum input frequency.








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