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Every sound starts with a vibration,
like the quivering of a guitar string.
The vibration squeezes and stretches
the air between the vibrating object
and your ear. This is a sound wave.
Sound
Silent space
Sound can travel through
solids, liquids, and gases,
but it can’t travel where
there is no matter. There is
no sound in space because
there is
no air.
Do all animals hear the same sounds?
Science and technology
Whispering
measures
about 20 decibels.
City traffic
reaches
approximately 85 decibels.
Drums
make a sound of
around 105 decibels.
Rustling leaves
make a
sound of only 10 decibels.
Measuring sound
Loudness is measured
in decibels.
When you blow
across a bottle,
the air inside vibrates. Small
air spaces vibrate more quickly
than large spaces, making higher
notes. So partly empty bottles
produce lower notes than
fuller ones.
H
a
n
d
s
o
n
How hearing works
When a sound reaches your ears,
it makes your eardrums vibrate.
The vibrations are passed to your
inner ear through tiny bones. From
here, nerves send messages to
your brain that allow you to
recognize the sound.
Sound waves travel through air like
a wave along a coiled spring.
Road-drills
measure about
110 decibels.
A lion’s roar
has been
recorded at 114 decibels.
Fireworks
can measure
120 decibels or more.
Jet engines
sometimes hit
140 decibels.
