Glossary

Hair cells (05)

The tiny sensors of sound in the cochlea.

Hair cells (31)

Delicate sound-sensing cells in the organ of Corti that are destroyed by overexposure to noise.

Harmonic (04)

The mode of vibration (or component of sound) whose frequencies are whole-number multiples of the frequency of the fundamental mode.

Harmonic (07)

A partial whose frequency is a multiple of the fundamental.

Harmonic distortion (20)

The creation of harmonics (frequency multiples) of the original signal by some type of nonlinearity in the system (the most common cause is overdriving some component).

Harmonic minor scale (09)

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

Harmonic singing (17)

Tuning vocal tract resonances to a harmonic of the vocal fold vibration frequency to produce single or multiple tones.

Harmonics (02)

Modes of vibration whose frequencies are whole-number multiples of the frequency of the fundamental mode.

Harmonics (13)

A series of partials with frequencies that are simple multiples of a fundamental frequency. (In a harmonic series, the first harmonic would be the fundamental, the second harmonic would be the first overtone).

Harpsichord (14)

A keyboard instrument in which strings are plucked by mechanical plectra.

Head voice (17)

Mode of singing associated with a light mechanism, passive vocalis muscle, and elongated, thin vocal folds.

Head-related transfer function (HRTF) (29)

The name given to the filter transfer function that describes the manner in which sounds from particular positions in space are transmitted to the ear canals of a listener, taking into account the relative positions and frequency-dependent shadowing effects of the head, pinnae, nose, etc.

Heavy mechanism (17)

Mode of vocal fold vibration in which the vocalis muscles are active, and the vocal folds are thick.

Helmholtz resonator (02)

A vibrator consisting of a volume of enclosed are with an open neck or port.

Helmholtz resonator (04)

A vibrator consisting of a volume of enclosed air with an open neck or port.

Helmholtz resonator (10)

A vibrator consisting of a volume of enclosed air with an open neck or port.

High-fidelity sound (25)

Sound that reproduces much of the spectrum, dynamic range, and spatial characteristics of the original sound and adds minimal distortion and noise.

High-level language (21)

A computer language that can be used to program a wide variety of computers rather than accessing register of a specific CPU.

Home theater (25)

A room designed and equipped for viewing movies as well as listening to music.

Horn loudspeaker (19)

A system that uses an acoustic horn to enhance sound radiation from a moving diaphragm.

Humbucking pickup (10)

A magnetic pickup with two coils designed to minimize hum caused by stray magnetic fields.

HVAC (23)

Heating, ventilating, and air-conditioning system.

HVAC (23)

Heating, ventilating, and air-conditioning system.

Hybrid synthesizer (27)

Use of a digital computer to control the analog circuitry in a synthesizer; also a synthesizer that combines analog and digital generators or modules.

Hysteresis (magnetic) (22)

The effect of past history on the magnetic state of a material; when a magnetic field is applied momentarily and removed, the material does not revert to its original state. Magnetic hysteresis may be described by a hysteresis loop, a graph of magnetization versus applied magnetic field.

IIC (impact isolation class) (32)

A number that describes the effectiveness of a ceiling-floor structure in attenuating impact sound.

Impedance (12)

The ration of the pressure to the velocity in a sound wave.

Impedance (18)

A measure of the opposition to the flow of electric current by a circuit element such as a resistor, capacitor, or inductor. Impedance is measured in ohms.

Impedance (19)

The ratio of voltage to current. The relevant current, in the case of source impedance or output impedance, is the current that the device can deliver; in the case of input impedance, it is the current that the device draws from the source.

Impedance (20)

The ratio of voltage to current. The relevant current, in the case of source impedance or output impedance, is the current that the device can deliver; in the case of input impedance, it is the current that the device draws from the source.

Impulsive wave (03)

A brief disturbance or pressure change that travels as a wave.

Inductor (18)

A device that stores energy by creating a magnetic field, usually within a coil of wire.

Infinite baffle (19)

A large baffle or an enclosure that prevents interference between sound radiated from the front and back of the speaker cone.

Infrasonic (32)

Having a frequency below the audible range.

Inharmonic overtones (09)

Overtones whose frequencies are not multiples of the fundamental (i.e., harmonics).

Inharmonic partial (07)

A partial that is not a harmonic of the fundamental.

Inharmonic partials (13)

Overtones or partial that are not harmonics of the fundamental.

Inharmonicity (14)

The departure of the frequencies of partials from those of a harmonic series.

Initial time delay (ITD) (25)

The time difference between the arrival of the direct sound and the first reflected sound at the ear.

Input-output (I/O) (21)

The portion of a computer that deals with transferring information into or out of the computer’s memory.

Intensity (05)

Power per unit area. The intensity of a sound wave is proportional to the square of the sound pressure.

Intensity (06)

Power per unit area; rate of energy flow.

Intensity level (06)

LI=10logI/I0, where I is intensity and I0 = 10^-12 W/m^2.

Intercostal muscles (17)

Muscles joining the ribs that are used for breathing.

Interference (03)

The interaction of two or more identical???? Waves which may support (constructive interference) or cancel (destructive interference) each other.

Interleaving (22)

A means for rearranging recorded data to minimize the loss of information due to playback errors.

Intermodulation (IM) distortion (20)

The creation of sum and difference frequencies from signals of two different frequencies.

Internal (expiratory) intercostals (17)

Intercostal muscles used to breath air out from the lungs.

Interpreter (21)

A computer program that translates statements in a computer language into machine instructions that are carried out one by one as soon as each statement is complete.

Intonation (09)

Refers to the degree of accuracy with which pitches are produced.

Jack (14)

A device in piano and harpsichord actions that moves up and down when a key is pressed. In the piano, the jack sets the hammer in motion; in a harpsichord, it carries the plectrum.

Joule (01)

A unit of energy or work; one joule is equal to one Newton-meter, also one watt-second.

Just intonation (09)

A system of tuning that attempts to make thirds, fourths, and fifths as consonant as possible; it is based on major triads with frequency ratios 4:5:6.

Just noticeable difference (jnd) (07)

The minimum change in stimulus that can be detected.

Kerr magneto-optical effect (22)

Rotation of the plane of polarization of light upon reflection from a magnetic material. The direction of rotation indicates the direction of the magnetization.

Kinetic energy (01)

Energy of motion; the capacity to do work by virtue of that motion; equal to one half mass times velocity squared.

Labial (14)

A flue pipe.

Laminar flow (14)

Fluid flow in which entire layers have the same velocity.

Languid (14)

A plate that partially blocks an organ pipe and forms one side of the flue.

Larynx (15)

The section of the vocal tract, composed mainly of cartilage, that contains the vocal folds.

Larynx (17)

The source of sound for speaking or singing.

Lay (12)

The slightly curved portion of a clarinet or saxophone mouthpiece that faces the reed.

Light mechanism (17)

Mode of vocal fold vibration in which the vocalis muscles are relaxed, and the vocal folds elongated and thin.

Linear (27)

A function or characteristic that varies in direct proportion to a control signal. In a typical linear control characteristic, an increase of 1 V adds a fixed amount to some parameter such as frequency.

Linear prediction (29)

A set of mathematical techniques designed to predict how a digital signal will behave based on a weighted sum of its most recent N values. The weights used in forming this sum are called prediction coefficients.

Linear predictive coding (LPC) (16)

Describing a speech waveform in terms of a set of time-varying parameters derived from speech samples.

Linear scale (05)

A scale in which moving a given distance right or left adds or subtracts a given increment.

Linear superposition (08)

Addition of two waves applied simultaneously to a linear system.

Linewidth (04)

The width delta ƒ of a resonance curve, usually measured at 71% of its maximum height; a measure of the sharpness of a resonance (a sharp resonance is characterized by a small linewidth).

Lingual (14)

A reed pipe.

Live-end, dead-end (LEDE) (25)

A control-room design philosophy that makes the front half of a control room absorptive and the back half diffusive.

Localization (05)

The ability to determine the location or direction of a sound source.

Logarithm (of a number) (05)

The power to which 10 (or some other base) must be raised to give the desired number.

Logarithmic scale (05)

A scale on which moving a given distance right or left respectively multiplies or divides by a given factor.

Logic gate (26)

A digital electronic circuit that has one or more binary (i.e., two-valued) inputs and one or more binary outputs. Output values are determined by logical operations such as AND, OR, and NOT.

Longitudinal vibration (02)

Vibration in which the principal motion is in the direction of the longest dimension.

Longitudinal wave (03)

A wave in which the vibrations are in the direction of the propagation of the wave; example: sound waves in air.

Looping (29)

The process of extending the duration of a digitally recorded sound by repeatedly outputting a portion of it.

Loudness (06)

Subjective assessment of the “strength” of a sound, which depends on its pressure, frequency, and timbre; loudness may be expressed in sones.

Loudness level (06)

Sound pressure of a 1000 Hz tone that sounds equally loud when compared to the tone in question; loudness level is expressed in phons.

Low-level language (21)

A computer language, such as assembly, designed to access the individual registers of a CPU.