Digital music, indeed most computer stuff these days, attracts it's share of abbreviations and acronyms... so many in fact that, as much as I've tried to make this site accessible to all users - including speech-enabled browsers, this area is the most time-consuming to code.

Therefore, these glossary pages are the best place for "decrypting".

Music glossary pages:

Digital Audio Dictionary: N-R

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Any background noise, hissing, or interference caused by other computer components such as hard disks.

(Noise reduction in our Mastering the Mix tutorial)

Non-destructive editing

Audio data on the hard disk remains in its original state, meaning that it is not physically changed during the editing.


What goes into a system comes out changed by its passage through that system-in other words, distorted. The ideal of an audio component and an audio system is to be linear, or nondistorting, with the image on one side of the mirror identical to the image on the other side.


A process by which the volume of an audio file is boosted to peak level.



An octave is a doubling or halving of frequency. 20Hz-40Hz is often considered the bottom octave. Each octave you add on the bottom requires that your speakers move four times as much air!


A unit of electrical resistance or impedance.

Ohm's Law

The basic law of electric circuits. It states that the current [I] in amperes in a circuit is equal to the voltage [E] in volts divided by the resistance [R] in ohms; thus, I = E/R.

OMS (Open Music System)

System expansion for Mac OS that allows MIDI devices and Apple computers to communicate.

Out of Phase

When speakers are mounted in reverse polarity, i.e... one speaker is wired +/+ and -/- from the amp and the other is wired +/- and -/+. Bass response will be very thin due to cancellation.


The sound level produced by a loudspeaker.


A condition in which a system is given too high of an input level. A common cause of distortion or product failure.


See Harmonics.



Pulse Code Modulation. A means of digital encoding.


Subdivisions of the data area on a hard disk. Every partition has its own disk drive ID.


Individual sections of a MIDI or audio track.

Passive Radiator

A device that looks just like an ordinary driver, except it has no magnet or voice coil. A passive radiator is usually a highly compliant device, with a similar cone material and surround found on regular active drivers. The radiator must usually be at least as large (or larger) than the driver it is aligned with. The passive radiator is tuned to Fb and used in place of a port.

Patch editor

Software application that provides the means to process and exchange the instrument sounds of an audio card's MIDI sound generator.

PC Card (formerly PCMCIA)

Standardized slot designed to connect hardware accessories to mobile computers.

PCI bus (Peripheral Component Interface)

Slot in the PC or Mac (bus) designed to take internal expansion cards.

Phase Cancellation

Where two oscillating frequencies move in and out of phase with each other. Chorus effects attempt to emulate this behaviour. Imagine two people playing a guitar riff. It would be very rare indeed for them to play exactly in time with each other. Where they don't, phase cancellation occurs.

Phase Coherence

The relationship and timing of sounds that come from different drivers (subs, mids, tweets) mounted in different locations.

Phase Distortion

A type of audible distortion caused by time delay between various parts of the signal.

Planar Source

Most electrostatics and magnetic planars have a large surface area. Think of a wide board dropped flat onto the water surface. The sound can be extremely coherent, but the listening window is effectively limited to being directly on-axis of both the left and right planar speaker.


Unable to run on their own, these software modules plug into a sequencer, adding new sound generators or effects to it.


Most multi-unit loudspeakers try to approximate a point-source. Think of a pebble dropped into the water and the expanding wave pattern away from impact. Obviously it is difficult to integrate multiple point-sources into a truly coherent expanding wave. The best designs do quite well with careful driver engineering and crossover development.


A speaker, for example, has a positive and a negative input terminal. Connecting a battery directly to the speaker will result in the diaphragm moving outward. If you reverse the battery leads, the diaphragm will move inward.

Caution: Too high of a voltage battery will also burn out the speaker!

Ported Enclosure:  

A type of speaker enclosure that uses a duct or port to improve efficiency at low frequencies.

Power (P)

The time rate of doing work or the rate at which energy is used. One equation for Power:

P = Volts^2 / Impedance


Product name for mobile Apple computers.



Highly complex arithmetic unit built into a chip - the brain of a computer, so to speak.

Push-Pull Configuration

One driver is mounted normally, the second is mounted so that it faces into the enclosure, both sharing the same internal volume and wired out of phase with one another. Although electrically out of phase with one another, the drivers are acoustically in phase since they move in the same direction. This alignment theoretically reduces second order harmonic distortion. 


Most common type of amplification that amplifies the negative and positive sides of the waveform separately. Allows for much higher power output than single-ended.


Or Pre-amp is a device that takes a source signal, such as from a turntable, tape-deck or CD player, and passes this signal on to a power-amplifier(s). The pre-amp may have a number of controls such as source selector switches, balance, volume and possibly tone-controls. 


Q or Quality Factor

Is a measure of damping. Modern home speaker systems have Q values ranging from < 0.5 to approx. 2.0.  Q values < .7  have no peak in the response. Q values around 0.5 are considered to be optimally damped, having a Bessel response. A Q of 1.0 is a Butterworth response. The lower the Q value, the better the transient response of the system, (less or no ringing), but the tradeoff is a larger required box size and the response begins to rolloff at a higher frequency. Another way to consider it is that the lower the Q, the more gradual the rolloff but the rolloff begins at a higher frequency.


An editing function of the sequencer. Out-of-time notes that don't fall into the desired rhythmic pattern are automatically shifted so they are in time.


RAM (Random Access Memory)

Term for the main memory of a computer.

RCA Connector

"Phono" plugs, used primarily as low-level connections between Phonographs/CD players/Tuners/Recievers/Amplifiers

Real time

In this context, real time means that an event - changes in pitch, sound or volume - is rendered as it occurs.

Recording Level

Volume setting of the recorded audio signal.


Software tool for adjusting the tempo of drum loops and other sampled phrases, distributed by Steinberg.

Red Book

Specification developed by Sony and Philips that sets forth the format of an audio CD.

Refrain (Chorus)

A musical phrase normally based on a single-note melody line. A key component of an arrangement, it is a song's central motif that ups its recognition factor.

Resonant frequency

Any system has a resonance at some particular frequency. At that frequency, even a slight amount of energy can cause the system to vibrate. A stretched piano string, when plucked, will vibrate for a while at a certain fundamental frequency. Plucked again, it will again vibrate at that same frequency. This is its natural or resonant frequency. While this is the basis of musical instruments, it is undesirable in music-reproducing instruments like audio equipment.

Ribbon Speaker

A type of speaker that uses a pleated conductor suspended between magnets. Most true ribbons are tweeters only. Sometimes confused with magnetic-planar speakers.

RMS (root-mean-square)

The square root of the mean of the sum of the squares. Commonly used as the effective value of measuring a sine wave's electrical power. A standard in amplifier measurements.

Roll-off (cut-off)

The attenuation that occurs at the lower or upper frequency range of a driver, network, or system. The roll-off frequency is usually defined as the frequency where response is reduced by -3 dB.