Sound
Sound is a kind of Energy
• It travels from one place to another in waves
• Sound waves are created when something
vibrates
– Vibrations travel through the air to your ears
Sound needs matter to travel through
• Can travel through
SOLIDS, LIQUIDS, and
GASES
• Travels at different rates
of speed through
different matter
• Sound travels the FASTEST
through SOLIDS
– The particles are packed
more tightly together
• Sound travels MEDIUM
through LIQUIDS
• Sound travels SLOWEST
through GASES
– The particles have more
space between them
Sound does not travel through
empty space
• Air contains particles
• Outer space does not – it is a “vacuum”
Pitch
• A sound's pitch is
determined by the speed
of its vibrations
– Faster vibrations result in a
higher pitch
– Slower vibrations result in
a lower pitch
– Different musical notes
have different pitches.
The tightness, or tension, of a string
can affect pitch
• If you have two strings
of the same length:
– one string is pulled
tightly and the other
string is loose
– The tight string will
produce a higherpitched sound than the
loose string because the
tight string will vibrate
faster.
Length and thickness of a string can
affect pitch
Length
• If two strings are pulled to
the same tightness
• the shorter string will make
the higher pitched sound
because it will make faster
vibrations.
Thickness
• Thicker strings will make
lower pitched sounds than
thinner strings of the same
length with the same
tension
Sound Reflection
• Sounds tend to reflect off of hard, rigid surfaces
• Called ECHO
• Places that reflect sounds over and over instead
of letting them spread out or be absorbed tend to
be very noisy
Sounds are absorbed by soft materials