What is a decibel (dB) ?

Answer 1

The decibel is derived from the bel, a unit of sound power measurement. It is actually a ratio, and has no meaning for absolute value:

bel = log(P1/P2)

decibel = 10*log(P1/P2)

For actual sound measurement, an arbitrary reference P2 is chosen (approximately equal to the sound power at the threshold of human hearing), so actual meaning can be ascribed to decibel readings.

The definition has been extended to other measurements. In particular, if sound pressure level (p1, p2) are measured, then

db = 20*log(p2/p1)

The unit is also used to indicate variations in voltage and current levels and amplifier power output. For voltage and current, the 20 factor is used, for power levels, 10.

Answer 2

It is the unit in which sound is measured. A whisper is of about 15 decibels, a restaurant maybe from 50 to 80. A jet plane tae off produces 150 decibels minimum sound.

Answer 3

The decibel is a logarithmic unit which is used in a number of
scientific disciplines. In all cases it is used to compare some
quantity with some reference value. Usually the reference value is the
smallest likely value of the quantity. Sometimes it can be an
approximate average value.

In acoustics the decibel is most often used to compare sound pressure,
in air, with a reference pressure. References for sound intensity,
sound power and sound pressure in water are amongst others which are
also commonly in use.

Reference sound pressure (in air) = 0.00002 = 2E-5 Pa (rms)
" " intensity = 0.000000000001 = 1E-12 W/m^2
" " power = 0.000000000001 = 1E-12 W
" " pressure (water) = 0.000001 = 1E-6 Pa

Acousticians use the dB scale for the following reasons:

1) Quantities of interest often exhibit such huge ranges of
variation that a dB scale is more convenient than a linear
scale. For example, sound pressure radiated by a submarine may
vary by eight orders of magnitude depending on direction.

2) The human ear interprets loudness on a scale much closer to
a logarithmic scale than a linear scale.

Answer 4

It is the unit in which sound is measured. A whisper is of about 15 decibels, a restaurant maybe from 50 to 80. A jet plane tae off produces 150 decibels minimum sound.

Answer 5

The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity relative to a specified or implied reference level

Answer 6

The decibel(one tenth) is a unit used in comparison of power levels in electrical communication or intensities of sound.
It is named after Alexander Graham Bell.

Answer 7

decibel is wave going time calculating

Answer 8

It's a measurement of sound. If you want more information on this subject, see the Wikipedia link below...

H a p p y
H o m e
T h e a t e r i n g !

Xe♫

Answer 9

Check out any dictionary or an encyclopedia.The best reference is any standard algorith manuel.
And dont be under the misconception that a point [.] is that simple as it appears.

Answer 10

The best option is to google it, but here is my answer: In our school, we use Vernier software and instruments. It has a microphone, magnetic field sensor, and others.