What is a decibel, and how is it measured?

The decibel unit is used to measure the intensity of a sounds. Check out our HowStuffWorks article to learn more about the decibel scale.

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Episode Transcript

Speaker 1 (00:00):
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(00:22):
Brain with today's question. What is a decibel and how
is it measured? The decibel, abbreviated dB, is the unit
used to measure the intensity of a sound. The decibel
scale is a little odd because the human ear is
incredibly sensitive. Your ears can hear everything from your fingertip

(00:43):
lightly brushing over your skin to a loud jet engine.
In terms of power, the sound of the jet engine
is about one trillion times more powerful than the smallest
audible sound. That's a huge difference on the decibel scale.
The smallest audible sound near total silence is zero dB.

(01:03):
A sound ten times more powerful as ten dB. A
sound a hundred times more powerful is twenty d B.
A sound a thousand times more powerful than total silence
is thirty d B. Here are some common sounds and
their decibel ratings. A whisper is about fiften dB. Normal
conversation is around sixty d B. A lawnmower is up

(01:26):
near ninety. A car horn is a hundred dB, a
rock concert or a jet engine is a hundred and
twenty d B, and a gunshot or a firecracker is
around a hundred and forty d B. These are the
levels when standing near the source of the sound. You
know from your own experience that distance affects the intensity

(01:46):
of sound. If you're far away, the power is greatly diminished.
Any sound above eight five dB can cause hearing loss,
and the loss is related both to the power of
the sound as well as the length of exposure. Sure
you know that you're listening to an eight five dB
sound If you have to raise your voice to be
heard by somebody else, eight hours of nine d dB

(02:09):
sound can cause damage to your ears. Any exposure to
a hundred and forty dB sound causes immediate damage and
may cause actual pain. Do you have any ideas or
suggestions for this podcast? If so, please send me an
email at podcast at how stuff works dot com. For
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(02:30):
how stuff works dot com.