One tenth of a bel (named after Alexander Graham Bell), a unit used in electronics and other fields to measure the strength of a sound or signal. Decibel measurements fall on a logarithmic scale and compare the measured quantity against a known reference. The following formula gives the number of decibels between two values: dB = n log (x/r) where x is the measured quantity, r is the reference quantity, and n is 10 for voltage and current measurements and 20 for power measurements.Abbreviation: dB.
A logarithmic unit of sound intensity; 10 times the logarithm of the ratio of the sound intensity to some reference intensity; SYN. dB, db.
A unit (dB) for measuring the relative strength of signal power. The number of decibels equals ten times the logarithm (base 10) of the ratio of the measured signal power to a reference power. One tenth of a bell.
Unit (symbol dB) of measure used originally to compare sound intensities and subsequently electrical or electronic power outputs; now also used to compare voltages. An increase of 10 dB is equivalent to a 10-fold increase in intensity or power, and a 20-fold increase in voltage. A whisper has an intensity of 20 dB; 140 dB (a jet aircraft taking off nearby) is the threshold of pain.
The difference in decibels between two levels of intensity (or power) L1 and L2 is 10 log10(L1/L2); a difference of 1 dB thus corresponds to a change of about 25%. For two voltages V1 and V2, the difference in decibels is 20 log10(V1/V2); 1 dB corresponding in this case to a change of about 12%. Commonly such differences are given now not as ratios but as absolute values; for example, 10 dBV corresponds to the voltage level V1 with V2 set equal to 1 volt. In acoustics, the absolute reference used in the power ratio is 10-16 watt per sq cm.
Decibel measurements of noise are often “A-weighted” to take into account the fact that some sound wavelengths are perceived as being particularly loud. + prikaži više