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(A - C) (D - G) (H - L) (M - Q) (R - U) (V - Z)

D - G

Damping (02)

Loss of energy of a vibrator, usually through friction.

Damping (04)

Energy loss in a system that slows it down or leads to a decrease in amplitude.

DASH (22)

A digital multi-track recorder with stationary heads used in professional studios.

Day-night level Ldn (30)

Equivalent sound level that adds 10 dB to sounds that occur during the night-time hours of 10:00 P.M. to 7:00 A.M..

Debugger (21)

A computer program designed to assist programmers in diagnosing and correcting the operation of another computer program.

Decibel (06)

A dimensionless unit used to compare the ratio of two quantities (such as sound pressure, power, or intensity), or to express the ration of one such quantity to an appropriate reference.

Delta (01)

The Greek letter delta, denoting change in some quantity.

Delta-sigma modulator (21)

An analog-digital (or digital-analog) conversion system that operates in 1-bit measurements at a very high sampling rate.

Demagnetization (22)

R asing a magnetically recorded signal by applying a rapidly varying magnetic field of large amplitude; in a demagnetized tape, the tiny magnetic "domains are oriented in nearly random directions.

Dendrite (08)

The part of a neuron that receives neural pulses from other neurons.

Diaphragm (17)

The dome-shaped muscle that forms a floor for the chest cavity .

Diatonic scale (09)

A scale of seven whole tones and semitones appropriate to a particular key.

Difference limen (07)

The minimum change in stimulus that can be detected.

Difference tone (08)

When two tones having frequencies ƒ1 and ƒ2 are sounded together a difference tone with frequency ƒ2-ƒ1 is often heard. (Properly this should be called the quadratic difference tone to distinguish it from the cubic and other difference tones).

Diffraction (03)

The spreading out of eaves when they encounter a barrier or pass through a narrow opening.

Diffraction horn (19)

A horn that has one broad dimension and one narrow one, designed to spread sound (by means of diffraction) in the direction of the narrow dimension.

Diffusion (25)

The mixing of sound to make it more homogeneous by scattering off irregular objects.

Digital electronics (26)

Electronic circuits in which the active elements (vacuum tubes and/or transistors) operate in their nonlinear mode, i.e., as switches that are turned either on or off.

Digital music synthesizer (29)

A digital device designed to synthetically create musical sounds.

Digital-analog converter (DAC) (21)

A circuit that converts numbers from a digital to an analog representation.

Digital-to-analog converter (DAC) (24)

A circuit that generates a voltage proportional to a digital number.

Digital-to-analog converter (DAC) (26)

A circuit that converts information-typically a waveform representing a sound from digital representation (such as a sequence of binary numbers representing the waveform) to analog form (such as voltage versus time).

Diode (18)

A device that allows easy current flow in one direction only.

Diphthong (15)

A combination of two or more vowels into one phoneme.

Dipole source (30)

A noise source in which two halves are vibrating in opposite phase (e.g., two loudspeakers connected in opposite polarity, or the air at the leading and trailing edges of a fan blade).

Direct current (dc) (18)

Electric current that flows in one direction only, such as that supplied by a battery.

Direct sound (23)

Sound that reaches the listener without being reflected.

Direct sound (23)

Sound that reaches the listener without being reflected.

Discrete Fourier transform (DFT) (28)

The discrete form of the Fourier transform, which associates with every time domain signal a frequency domain spectrum and vice versa.

Dissonance (08)

Roughness that results when tones with appropriate frequency difference are presented simultaneously.

Distortion (07)

An undesired change in waveform. Two common examples are harmonic distortion and intermodulation distortion. Harmonic distortion means that harmonics are generated by altering the waveform in some way (“clipping” the peaks, for example). Intermodulation distortion refers to the generation of sum and difference tones.

Distortion (18)

A measure of the difference between the output and input signals in an amplifier.

Distortion (20)

Signals that appear in the output of a sound reproduction system that were not present in the original input signal.

Dither (21)

A low-amplitude noise added to an analog signal to ensure that low-amplitude signals are decorrelated from the sampling process, thus improving their distortion and noise characteristics.

Dither (22)

Low-level noise added to the signal to reduce the effect of quantization error.

Dolby system (22)

A widely used noise-reduction system that boosts low-level high-frequency signals when recorded and reduces them in playback.

Domain (magnetic) (22)

A tiny region in which the atomic magnets point in the same direction.

Doppler effect (03)

The shift in apparent frequency when the source or observer is in motion.

Downsampling (21)

The process of lowering the sampling rate of a digital signal by discarding samples: a 1/M downsampler would retain 1 out of every M samples, for example, of a suitably filtered digital signal.

DRAM (dynamic random access memory) (21)

A type of volatile semiconductor memory that stores large amounts of data in a small space. It must be frequently refreshed.

Drawbar (26)

A multi-position control on a Hammond organ that selects the amount of a particular harmonic frequency (or other sound component) that will be used to synthesize a tone.

Drone cone (19)

A passive loudspeaker that has no voice coil or magnet

Dynamic microphone (20)

A microphone that generates an electrical voltage by the movement of a coil of wire in a magnetic field.

Dynamo (26)

A device that generates electrical energy by moving a wire in the presence of a magnetic field, or by moving a magnet near a wire.

Eardrum (tympanum) (05)

The fibrous membrane that terminates the auditory canal and is caused to vibrate by incoming sound waves

Early sound (23)

Sound that reaches the listener within a short time (about 50 ms) after the direct sound.

Early sound (23)

Sound that reaches the listener within a short time (about 50 ms) after the direct sound.

Edgetone (14)

The sound produced when an air jet encounters a sharp edge or wedge and oscillates back and forth, first passing on one side, then the other.

EEPROM (electrically erasable/ programmable read-only memory) (21)

Read-only memory that can be erased and reprogrammed while still in the computer.

Eight-to-fourteen modulation (DFM) (22)

A code used to represent blocks of eight numbers on a compact disc.

Electret-condenser microphone (20)

A condenser microphone that has an electrified foil between the plates of the capacitor, thus eliminating the need for a polarizing voltage as required in an air-dielectric condenser microphone.

Electroencephalogram (EEG) (31)

R ecord of electrical potentials at several points in the brain (sometimes referred to as "brain waves).

Electromagnetic force (04)

The force that results from the interaction of an alternating electric current with a magnetic field.

Electromagnetic induction (19)

Generation of an electrical voltage in a wire that moves across a magnetic field.

Electromagnetic induction (20)

Generation of an electrical voltage in a wire that moves across a magnetic field

Elektronische musik (27)

A type of music based on the control of many electronically generated signals that together form a musical result.

Embouchure (12)

The lip position used in playing a wind instrument. The embouchure hole in a flute is the hole through which the lips blow air.

Energy (18)

The ability to do work. Various units are used to measure energy, such as joules, BTU’s, calories, or foot-pounds .

Enharmonic notes (09)

Two different notes that sound the same on keyboard instruments (e.g., G# and Ab).

Envelope (02)

Time variation of the amplitude (or energy) of a vibration.

Envelope (05)

Time history of the amplitude.

Envelope (07)

The amplitude of a tone as a function of time.

Envelope follower (27)

A circuit that generates a control voltage that duplicates the amplitude envelope of a signal taken from an acoustical musical instrument or other sound source.

Epiglottis (15)

A thin piece of cartilage that protects the glottis during swallowing.

EPROM (erasable/ programmable read-only memory) (21)

Read-only memory that can be erased by ultra-violet light and then reprogrammed.

Equal energy hypothesis (31)

Postulates that risk of hearing loss is determined by the total amount of noise energy to which the ear is exposed each day, irrespective of its distribution in time.

Equal temperament (09)

A system of tuning in which all semitones are the same; namely, a frequency ratio of 2^1/12 = 1.059.

Equal temporary effect (TTS) hypothesis (31)

Postulates that risk of permanent hearing loss increases with average temporary loss (TTS).

Equalization (22)

Boosting some frequencies and attenuating others to meet some prescribed recipe. Equalization is usually applied during both recording and playback.

Equalization (24)

Changing the gain of a sound system at certain frequencies to compensate for room resonances and other peaks in the response curve.

Equivalent level (Leq) (30)

Sound pressure level that would give the same total energy as the noise being described.

Eustachian tube (05)

A tube connecting the middle ear to the oral cavity that allows the average pressure in the middle ear to equal atmospheric pressure.

Exponent (05)

The number expressing the power to which 10 or some other number is raised.

Exponential (27)

A function or characteristic that varies as ex. In a typical exponential control characteristic, an increase of 1 V doubles some parameter such as frequency.

External (inspiratory) intercostals (17)

Intercostal muscles used to breath air into the lungs.

FAR Part 36 (32)

A regulation by the Federal Aviation Administration that sets standards for noise from new aircraft.

Fast Fourier transform (FFT) (28)

A particularly efficient way to compute the discrete Fourier transform (DFT).

Fechner’s (Weber’s) law (05)

An empirical law expressing the way in which sensation varies with stimulus.

Feedback (11)

The addition of a part of the output of a system to the input; positive feedback is used to sustain oscillations in wind instruments, audio generators, etc.

Feedback (12)

Use of an output signal to control or influence the input. Positive feedback, if great enough, can cause a system to oscillate.

ƒ-holes (10)

The openings in the top plate of a string instrument shaped like the letter ƒ.

Filter (15)

A device that allows signals in a certain frequency range to pass and attenuates other.

Filter (18)

An electrical circuit that passes alternating currents of some frequencies and attenuates other. Basic filter types are high-pass, low-pass, band-pass, and band-reject.

Filters (high-pass and band-pass) (11)

Acoustics elements that allow certain frequencies to be transmitted while attenuating others. A high-pass filter allows all components above a cutoff frequency to be transmitted; a band-pass filter allows frequencies within a certain band to pass.

Flip-flop (21)

A digital circuit capable of acting as a memory for a single bit of information by remaining in one state until it is actively placed in a second state.

Floating point (21)

A means of representing numbers using one set of bits for an exponent x and another set for a mantissa m, interpreted as m times b to the power of x (b is typically two).

Flow rate (17)

The volume of air that flows past a point and is measured per second.

Flue (14)

The narrow windway between the languid and lower lip in a flue pipe

Flue pipe (14)

An organ pipe that produces sound by means of a jet of air passing through the flue and striking the upper lip.

Foldover (21)

In a digital signal, the misrepresentation of frequencies above half the sampling rate at incorrect frequencies below half the sampling rate.

Force (01)

An influence that can deform an object or cause it to change it’s motion.

Formant (12)

A range of frequency to which a system responds preferentially or which is emphasized in its output.

Formant (17)

A resonance of the vocal tract.

Formant synthesis (16)

Employs the source-filter theory of speech production to synthesize speech.

Formants (15)

Vocal tract resonances that determine speech sounds.

Fourier analysis (07)

The determination of the component tones that make up a complex tone or waveform.

Fourier synthesis (07)

The creation of a complex tone or waveform by combining its spectral components.

Free field (23)

A reflection-free environment, such as exists outdoors or in an anechoic room, in which sound pressure varies inversely with distance.

Free field (23)

A reflection-free environment, such as exists outdoors or in an anechoic room, in which sound pressure varies inversely with distance.

Free field (24)

That part of the sound field where the sound level decreases by 6 dB for each doubling of distance.

Frequency (02)

The number of vibrations per second; expressed in hertz(Hz); also the inverse of period.

Frequency divider (26)

A circuit that accepts a single frequency as an input and outputs multiple signals at frequencies that are integer divisors of the input frequency.

Frequency domain (28)

The representation of a signal as a function of frequency , such as frequency-dependent amplitude or phase.

Frequency modulation (FM) (20)

The method of radio broadcasting in which the frequency of a carrier wave is modulated (altered slightly) by the audio signal. The FM band, which extends from 88 to 109 MHz, allows stations sufficient bandwidth to transmit high-fidelity stereophonic sound.

Fresnel number (32)

The parameter that determines- the sound diffracted around a barrier.

Fricative consonant (16)

Consonant that is formed by constricting air flow in the vocal tract (e.g., f, v, s, z, th, sh).

Fricatives (15)

Consonants that are formed by constricting air flow in the vocal tract (such as f, v, s, z, th, sh, etc.).

Function generator (18)

A wave generator that provides several different waveforms or functions at the desired frequency.

Functional reserve capacity (FRC) (17)

Volume of air in the lungs at the end of a quiet exhalation.

Fundamental (04)

The mode of vibration (or component of sound) with the lowest frequency.

Fundamental (07)

The lowest common factor in a series of harmonic partials. The fundamental frequency of a periodic waveform is the reciprocal of its period.

Fundamental mode (02)

The mode of the lowest frequency.

Glottis (15)

The V-shaped opening between the vocal folds.

Gramophone (22)

Flat-disk recording system invented by Emile Berliner in 1891.

Gravity (01)

The force exerted by the Earth on all objects on or near it.

Grid (26)

A fine mesh of wires in a vacuum tube that controls the flow of electrons from cathode and anode.

(A - C) (D - G) (H - L) (M - Q) (R - U) (V - Z)

Copyright 2008, by the Contributing Authors. Cite/attribute Resource . admin. (2005, January 25). Glossary. Retrieved January 07, 2011, from Free Online Course Materials — USU OpenCourseWare Web site: http://ocw.usu.edu/Electrical_and_Computer_Engineering/Science_of_Sound/Glossary.htm. This work is licensed under a Creative Commons License Creative Commons License