An increase of three decibels is approximately a doubling of power. One decibel (0.1 bel) equals 10 times the common logarithm of the power ratio. One bel is a power ratio of 10:1, and is divided into ten decibels. decibel (dB), unit for expressing the ratio between two physical quantities, usually amounts of acoustic or electric power, or for measuring the relative loudness of sounds. It expresses them as an exponential function. Throughout the 20th century, the Bell name was ubiquitous. A decibel (or dB) measures ratios of power or intensity. Quite a lot was named after Alexander Graham Bell. INCREASE IN POWER LEVELS (WATTS) Formula is dB=10*log(P1/P2) DeciBels Output Signal StrengthĪTTENUATION OF AMPLITUDE (VOLTS or AMPS) Formula is dB=20*log(A1/A2) DeciBels Output Signal Strength A hundred miles away, the sound level reached more than 170 dB, deafening everyone who survived. In 1883, the volcano on the Indonesian island of Krakatoa erupted. Loud thunder is approximately 110 dB, and 120 dB borders on the threshold of pain.

A decibel is one tenth of a bel (B), a unit named after Graham. A normal conversation is typically from 60 to 70 dB, and a noisy factory from 90 to 100 dB. The decibel (dB) is a unit used to measure sound intensity and other physical quantities. One Bel is when the output signal is 10x that of the input, and one deciBel is 1/10th of a Bel.Ī whisper is about 20 dB. A deciBel is the logarithm of the ratio of the two levels. Created in the early days of telephony as a way to measure cable and equipment performance and named after Alexander Graham Bell, deciBels (dBs) are a relative measurement derived from two signal levels: a reference input level and an observed output level. One deciBel is considered the smallest difference in sound level that the human ear can discern. Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005 deciBelA unit of measurement of the loudness or strength of a signal.

Decibel unit