SCIENCE OF SOUND239 100 dB
The blast of a car horn. 110 dB
The sound of a
thunderstorm overhead. 120 dB
The roar of a jet
aircraft taking off.PITCH AND TONE
The way we hear a sound depends on the
shape of the sound waves. The spacing of
waves affects the frequency or pitch of the
sound. Closely packed waves indicate high
pitch, while stretched out waves are low-
pitched. A clear-toned sound like a bell
creates smooth waves, while harsh tones such
as drumbeats make jagged-looking waves.
Sonogram
A sound diagramBat calls The echolocation
calls produced by bats are
loud but so high pitched
that most people cannot
hear them at all. Bats have
incredibly sharp hearing
and use faint echoes from
nearby surfaces to pinpoint
prey or detect obstacles. SCIENCEBreaking the sound barrier
When a supersonic aircraft breaks the speed of
sound, it overtakes its own sound waves, pushing
them closer together to create a “sonic boom”.
A whipcrack is a type of sonic boom, caused when
the whip tip breaks the sound barrier.The “sonic shock” caused by a
supersonic aircraft causes water in
the atmosphere to condense, forming
a visible cone, or collar, of vapor.Seeing with sound Sound waves bounce
off objects in the same way light waves do.
Dolphins and bats are able to use these
echoes to picture objects around them.
With the aid of computer-imaging
software that converts sound waves into
pictures, we can do the same.
FIRST PHOTO
Advanced ultrasound
scanners can produce
amazingly detailed
images such as this
unborn baby. ULTRASOUND SCANNERS
send out high-pitched waves and
pick up the echoes to create an image.Echolocation
Seeing with sound(c) 2012 Dorling Kindersley. All Rights Reserved.(c) 2012 Dorling Kindersley. All Rights Reserved.