# decibel

decibel
/des"euh bel', -beuhl/, n. Physics.
1. a unit used to express the intensity of a sound wave, equal to 20 times the common logarithm of the ratio of the pressure produced by the sound wave to a reference pressure, usually 0.0002 microbar.
2. a unit of power ratio, the number of units being equal to a constant times the logarithm to the base 10 of the intensities of two sources.
3. a unit used to compare two voltages or currents, equal to 20 times the common logarithm of the ratio of the voltages or currents measured across equal resistances. Abbr.: dB, db
[1925-30; DECI- + BEL]

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▪ unit of measurement
(dB), unit for expressing the ratio between two amounts of electric or acoustic power or for measuring the relative loudness of sounds. One decibel (0.1 bel) equals 10 times the common logarithm of the power ratio—i.e., doubling the intensity of a sound means an increase of a little more than three dB. In ordinary usage, specification of the intensity of a sound implies a comparison of the intensity of the sound with that of a sound just perceptible to the human ear. For example, a 90-dB, or 9-bel, sound is nine powers of 10 (i.e., 109, or 1,000,000,000) times more intense than a barely detectable sound. Decibels are also used to express the ratio of the magnitudes of two electric voltages or currents (or analogous acoustic quantities); in this usage one dB equals 20 times the common logarithm of the ratio.

The term bel is derived from the name of Alexander Graham Bell (Bell, Alexander Graham), inventor of the telephone.

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Universalium. 2010.

### Look at other dictionaries:

• Decibel — Décibel Pour les articles homonymes, voir Décibel (homonymie). Le décibel (dB) est une unité logarithmique de mesure du rapport entre deux puissances. C’est une grandeur sans dimension en dehors du système international. Elle est utilisée… …   Wikipédia en Français

• Decibel — Basisdaten Entwickler KDE / supported by NLNet and basysKom Aktuelle Version …   Deutsch Wikipedia

• décibel — [ desibɛl ] n. m. • 1932; de déci et 2. bel 1 ♦ Métrol. Unité, égale au dixième du bel, servant à exprimer le rapport de deux puissances (acoustiques, électriques, etc.), notamment d une puissance donnée par rapport à une puissance de référence… …   Encyclopédie Universelle

• decibel — DECIBÉL, decibeli, s.m. Unitate de măsură a intensităţii sonore, egală cu o zecime dintr un bel. – Din fr. décibel. Trimis de dante, 13.09.2007. Sursa: DEX 98 ﻿ decibél s. m., pl. decibéli; simb. dB Trimis de siveco, 10.08.2004. Sursa: Dicţionar… …   Dicționar Român

• Decibel — Saltar a navegación, búsqueda Decibel puede referirse a: decibelio en inglés, nombre de la unidad de comparación de magnitudes; a la rock progresivo y del rock en oposición, a Decibel, el framework de comunicaciones en tiempo real de KDE 4.… …   Wikipedia Español

• dècibel — m 1. {{001f}}fiz. jedinica za mjerenje razlika u snazi (simbol dB), najčešće u elektronici; u akustici mjeri razlike u pritiscima u mediju koji prenosi zvuk (jedan decibel je približno najmanja razlika intenziteta zvuka koju može zamijetiti… …   Veliki rječnik hrvatskoga jezika

• decibel — 1928, from DECI (Cf. deci ) + BEL (Cf. bel) (n.) …   Etymology dictionary

• decibel — s. m. Décima parte do bel, unidade de medida que serve, em acústica, para definir uma escala de intensidade sonora (símbolo: dB). [A voz média tem por intensidade 55 dB.] …   Dicionário da Língua Portuguesa

• decibel — o decibelio sustantivo masculino 1. Área: física Unidad que se utiliza para medir la intensidad de un sonido …   Diccionario Salamanca de la Lengua Española

• decibel — m. Fís. decibelio …   Diccionario de la lengua española

• decibel — ► NOUN ▪ a unit of measurement expressing the intensity of a sound or the power of an electrical signal. ORIGIN from DECI (Cf. ↑deci ) + bel, a unit (= 10 decibels) named after Alexander Graham Bell (1847 1922), inventor of the telephone …   English terms dictionary