Glossary

Magnetic field (B-field) (19)

A map of the magnetic force around a current-carrying wire or magnet.

Magnetic flux (19)

A magnetic “current” that flows from a north pole to a south pole. The product of B-field and area.

Magnetic induction (19)

An electrical voltage appears on a conductor that moves in a magnetic field.

Magneto-resistive reading head (22)

Tape-reading head with a material whose resistance changes in a magnetic field. A magneto-resistive head senses magnetic flux (field), whereas the more common inductive head senses rate of change of flux (field). Magneto-resistive heads can be made very thin.

Major diatonic scale (09)

A scale of seven notes with the following sequence of intervals: two whole tones, one semitone, three whole tones, and one semitone.

Major triad (08)

A chord of three notes having intervals of a major third and a minor third, respectively (as C: E: G).

Masking (06)

The obscuring of one sound by another.

Masking (16)

Obscuring of one sound by another.

Mass (01)

A measure of resistance to change in motion; equal to force divided by acceleration.

Meantone temperament (09)

A system of tuning which raises or lowers various notes from their Pythagorean values by quarters of the syntonic comma.

Mel (07)

The unit of subjective pitch; doubling the number of mels doubles the subjective pitch for most listeners. The critical band is about 100 mels wide.

Melodic minor scale (09)

A scale with a flatted third while ascending, and a flatted third, sixth, and seventh while descending. Example, in the key of C: Ascending: C, D, Eb, F, G, A, B, C. Descending: C, D, Eb, F, G, Ab, Bb, C.

Memory, nonvolatile (21)

A type of computer memory that does not disappear when the power is turned off, such as a disk or tape memory.

Memory, volatile (21)

A type of computer memory that disappears more or less immediately when the power is turned off, such as random-access memory (RAM).

Memory, working (21)

The (typically volatile) memory in a computer used temporarily while a program is running.

Microcontroller (21)

A single integrated circuit chip containing a CPU, memory, and I/O used for small control applications.

Microprocessor (21)

The central processing unit of a computer constructed on a single integrated circuit chip.

Microtone (09)

Any interval smaller than a semitone.

Middle register (17)

A combination of light and heavy mechanism that lies between the chest and head registers.

MIDI (29)

Musical instrument digital interface communications standard adopted widely in the music synthesizer industry in the early 1980s.

MIDI (musical instrument digital interface) (21)

An interface that allows a synthesizer or other electronic instrument to be controlled by a computer or another electronic instrument (see Section 29.8).

MiniDisc (MD) (22)

A miniature version of a Compact Disc for digital sound recording.

Minor scale (09)

A scale with one to three notes lowered a semitone from the corresponding major scale. The three minor scales are natural minor, harmonic minor, and melodic minor.

Minor triad (08)

A chord of three notes having intervals of a minor third and a major third, respectively (as C: Eb: G).

Mobility (mechanical admittance) (10)

The ratio of velocity to force (called input admittance or driving point mobility if velocity and force are measured at the same point).

Modulate (08)

To change some parameter (usually amplitude or frequency) of one signal in proportion to a second signal.

Modulator (27)

A device that controls (modulates) a characteristic of one signal (amplitude, frequency, etc.) with another signal.

Modulus of elasticity (13)

The ration of stress to strain; also called modulus of elasticity.

Monaural (25)

Sound reproduction using one microphone to feed a single headphone, such as is used in telephone communication.

Monophonic (25)

Sound reproduction using one microphone to feed one or more loudspeakers with one signal.

Monopole source (30)

A noise in which the entire radiating surface vibrates in phase.

Mouthpiece (11)

The part of a brass instrument that couples the vibrating lips to the air column.

Mouthpipe (11)

Tapered tubing that connects the mouthpiece to the main section of a brass instrument.

MP3 (29)

The common name given to digital audio that is encoded according to a particular standard known as the motion picture expert's group (MPEG)-1, Layer III. The perception-based encoding process compresses the digital representation greatly, allowing it to be readily transmitted or stored.

Multiprocessing (21)

The simultaneous use of more than one processor (CPU) to run one or more programs.

Multitasking (21)

A computer technique of rapidly switching from one task to another in order to simulate the execution of many tasks at once.

Music synthesis (29)

Either computer-based composition of music or the synthesis of musical sounds based on computer or electronics technology.

Musical staff (08)

A five-line graph on which musical notes are written. A clef sign shows the exact location of a particular note.

Musique concrete (27)

sounds of nature (rather than the "abstract sounds of traditional musical instruments).

Mute (11)

An acoustics device that alter the timbre and loudness of a musical instrument.

Nasals (15)

Consonants that make us of resonance of the nasal cavity (m, n, ng).

Natural minor scale (09)

A scale with a flatted third, sixth, and seventh. Example: in the key of C: C, D, Eb, F, G, Ab, Bb, C.

Near field (24)

That part of the sound field where the sound level varies from point to point because of the radiation pattern of the source.

Neuron, or nerve cell (08)

Building block of the nervous system that both transmits and processes neural pulses.

Newton (01)

A unit of force.

Nibble (21)

An ordered collection of 4 bits of computer memory.

Node, or nodal line (02)

A point or line where minimal motion takes place.

Nodes (13)

Points or lines that do not move when a body vibrates in one of its modes.

Noise criteria (NC) curves (23)

A family of curves defining levels of room noise in several octave bands.

Noise criteria (NC) curves (23)

A family of curves defining levels of room noise in several octave bands.

Nonlinear synthesis (29)

The process of synthesizing sounds through mathematically nonlinear processes that generate output frequencies different from those used as input, such as frequency modulation (FM).

NOR gate (not-or-gate) (21)

NOT-OR circuit, which outputs 0 if either (or both) inputs are 1 (i.e. the output is opposite of an OR gate).

Normal modes (02)

Independent ways in which a system can vibrate.

Nut (10)

The strip of hard material that supports the strings at the head end.

Nyquist frequency (21)

Half the sampling frequency. Frequencies above the Nyquist frequency, if not filtered out before sampling, will appear at other frequencies less than the Nyquist frequency (aliasing or foldover).

Octave (07)

The basic unit in most musical scales. Notes judged an octave apart have frequencies nearly in the ratio 2:1.

Ohm’s law (18)

A fundamental law that relates electric current I, voltage V, and resistance R; written , or V=IR.

Operating system (21)

A “master” computer program residing permanently in a computer that controls the execution of other programs.

Operational amplifier (op amp) (18)

A high-gain amplifier with a large amount of negative feedback and high input impedance.

Organ of Corti (05)

The part of the cochlea containing the hair cells; the “seat of hearing”.

Oscillator (26)

A circuit that outputs a signal with a specific waveform at a controllable frequency, amplitude, and phase.

OSHA (Occupational Safety and Health Agency) (32)

The agency that publishes industrial safety standards set by the Occupational Safety and Health Act.

Ossicles (05)

Three small bones of the middle ear that transmit vibrations from the eardrum to the cochlea.

Oversampling (21)

(1) Increasing the sampling rate by some factor L (see upsampling); (2) Any frequency that is sampled more then twice per period is said to be undersampled.

Oversampling (22)

A method for increasing the rate of digital samples to the DAC in order to avoid the need for an analog filter with a sharp cutoff.

Overtone (04)

A component of a sound with a frequency greater than the fundamental frequency.

Overtones (13)

Upper partials or all components of a tone except the fundamental.

Palate (15)

The roof of the mouth.

Panning (27)

Applying a set of output signals to a series of loudspeakers sequentially so that the sound seems to move in space.

Partial (04)

A component of sound; includes the fundamental plus the overtones.

Partial tone (07)

One of the components in a complex tone (it may or may not be a harmonic of the fundamental).

Patch (27)

(Verb) to interconnect; or (noun) a set of interconnections that causes a synthesizer to produce certain types of sounds.

Peak clipping (16)

Limiting the amplitude of a waveform do that peaks in the waveform are eliminated; this distorts the waveform.

Pentatonic scale (09)

A scale of five notes used in several musical cultures, such as Chinese, Native American, and Celtic.

Period (02)

The time duration of one vibration; the minimum time necessary for the motion to repeat; also the inverse of frequency.

Period (07)

The smallest increment of time over which a waveform repeats itself.

Periodic quantity (07)

One that repeats itself at regular time intervals.

Periodicity pitch (07)

Pitch determination on the basis of the period of the waveform of a tone.

Permanent threshold shift (NIPTS) (31)

The amount that the threshold of hearing is raised irreversibly by exposure to noise.

Pharynx (15)

Lower part of the vocal tract which connects the mouth to the trachea.

Pharynx (17)

The lower part of the vocal tract connecting the larynx and the oral cavity.

Phase (07)

The fractional part of a period through which a waveform has passed, measured from a reference.

Phase (08)

The fractional part of a period through which a waveform has passed. Phase is often expressed as an angle that is an appropriate fraction of 360°.

Phase difference (04)

A measure of the relative positions of two vibrating objects at a given time; also the relative positions, in a vibration cycle, of a vibrating object and a driving force.

Phase difference (08)

The difference in phase angle between two simple harmonic motions or waves. (If the phase difference is zero, they are in phase; if it is 180°, they are in opposite phase).

Phase vocoder (29)

A sound analysis-synthesis system based on measuring the time-varying amplitude and frequency characteristics of a complex sound. The intermediate data can be manipulated to independently shift the pitch and/or duration of the synthesized sound as compared to the original.

Phon (06)

A dimensionless unit used to measure loudness level; for a tone of 1000 Hz, the loudness level in phons equals the sound pressure level in decibels.

Phonemes (15)

Individual units of sound that make up speech.

Phonemes (16)

Individual units of sound that make up speech.

Phonetics (15)

The study of speech sounds.

Physical modeling synthesis (29)

The process of synthesizing sounds by deriving and operating mathematical models that describe the physical operation of real or imaginary sound sources.

Piezoelectric crystal (19)

A crystal that generates an electric voltage when it is bent or otherwise distorted in shape or, conversely, distorts in response to a voltage.

Piezoelectric crystal (20)

A crystal that generates an electric voltage when it is bent or otherwise distorted in shape.

Pink noise (25)

Random noise that has the same power in each octave or octave band.

Pink noise (27)

Low-pass-filtered random noise for which the energy contained in each octave band is the same.

Pinna (05)

The external part of the ear.

Pitch (07)

An attribute of auditory sensation by which sounds may be ordered from high to low.

Pitch bend (27)

A control that lowers or raises an otherwise fixed pitch (such as one specified by a note on a keyboard).

Pitch shifting (29)

The process of accurately resampling a digitally recorded sound at a new sampling rate, thus shifting the pitch when the resampled signal is played back at the same rate as the original recording.

Pixel (21)

A picture element on a monitor.

Place theory of pitch (07)

A view of the basilar membrane as a frequency analyzer of high resolution; pitch is determined by sensing the place on the basilar membrane that has maximum excitation.

Plectrum (14)

The small tongue of quill, leather, or plastic that plucks the string of a harpsichord.

Plosives (15)

Consonants that are produced by suddenly removing a constriction in the vocal tract (p, b, t, d, k, g).

Poles and zeros (28)

Maximum and minimum values of a transfer function, associated with resonances and anti-resonances, respectively.

Popping frequency (11)

The lowest resonance of a brass instrument mouthpiece.

Potential (18)

A measure of the electrical force, or pressure, that causes a current to flow; typically supplied by a generator or a battery and measured in volts.

Potential energy (01)

Stored energy; the capacity to do work by virtue of position.

Power (01)

The rate of doing work; equal to work or energy divided by time.

Power (18)

The rate at which energy is supplied or the rate at which work is done. It is measured in watts; one watt equals one joule per second.

Power gain (18)

The ration of output power to input power.

Precedence effect (05)

If similar sounds arrive within about 35 ms of each other, the apparent direction is the direction from which the first arriving sound comes.

Precedence effect (23)

The ability of the ear to determine the direction of a sound source from the direct sound without being confused by the early sound that follows.

Presbycusis (31)

Gradual loss of hearing with age, especially at high frequency.

Pressure (01)

Force divided by area.

Pressure zone microphone (PZM) (20)

A microphone that responds to the pressure build-up on a particular solid surface, caused by the pressure from the sound source.

Prosodic feature (15)

A characteristic of speech, such as pitch, rhythm, and accent, that is used to convey meaning, emphasis, and emotion

Psychoacoustics (05)

The study of the relationship between sound and the sensation it produces. The psychophysics of sound.

Psychophysics (05)

The study of the relationship between stimuli and the sensations they produce.

Pulse-code modulation (22)

A means for representing a sequence of binary numbers by a series of electrical pulses.

Pulse-code modulation (PCM) (21)

A particular type of digital signal that encodes a corresponding analog signal as an ordered collection of evenly spaced samples of its amplitude, with each sample linearly encoded as a certain number of bits.

Punch in/punch out (22)

Editing a recording by substituting a new section.

Purfling (10)

The thin wood strip near the edge of the top or back plate of a string instrument.

Push-pull (20)

An arrangement sued in power amplifiers; a positive voltage in the input causes the current to rise in one transistor, whereas a negative voltage does the same for another transistor. Push-pull amplifiers usually have an output transformer but do not require complementary transistors.

Pythagorean comma (09)

The small difference between two kinds of semitones (chromatic and diatonic) in the Pythagorean tuning; a frequency ration of 1.0136 corresponding to 23.5 cents.

Pythagorean tuning (09)

A system of pitches based on perfect fifths and fourths.

Q (27)

A filter parameter that specifies the sharpness of a resonance (technically, ratio of energy stored to energy dissipated per cycle).

Q (directivity factor) (24)

Comparison of the sound power radiated directly ahead of a sound source to that radiated in all directions.

Q factor (19)

Ratio of stored energy to the energy dissipated during each cycle of oscillation. Measure of the sharpness of a resonance.

Quadraphonic (25)

Sound reproduction using four microphones to feed four loudspeakers; usually two are in front of the listener and two are behind or to the sides.

Quadrupole source (30)

A noise source in which four parts vibrate alternately in phase.

Quantization error (21)

The difference between the quantized value and the “true” value of the sample.

Quantizing (21)

The process of assigning a discrete digital value to a theoretically continuous analog amplitude.