.
The Intensity Of Sound
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 brushing lightly over your skin to
a loud jet engine.
In
terms of power, the sound of the jet engine is about 1,000,000,000,000 times
more powerful than the smallest audible sound. That's a big difference!
On
the decibel scale, the smallest audible sound (near total silence)
is 0 dB.
A
sound 10 times more powerful is 10 dB. A sound 100 times more powerful than
near total silence is 20 dB.
A
sound 1,000 times more powerful than near total silence is 30 dB. Here are some
common sounds and their decibel ratings:
·
Near total silence - 0 dB
·
A whisper - 15 dB
·
Normal conversation - 60 dB
·
A lawnmower - 90 dB
·
A car horn - 110 dB
·
A rock concert or a jet engine -
120 dB
·
A gunshot or firecracker - 140 dB
You
know from your own experience that distance affects the intensity of sound --
if you are far away, the power is greatly diminished.
All
of the ratings above are taken while standing near the sound.
Any
sound above 85 dB can cause hearing loss, and the loss is related
both to the power of the sound as well as the length of exposure.
You
know that you are listening to an 85-dB sound if you have to raise your voice
to be heard by somebody else.
Eight
hours of 90-dB sound can cause damage to your ears; any exposure to 140-dB
sound causes immediate damage (and causes actual pain).
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