Properties of Sound
They are three fundamental
properties of sound :
Speed
Frequency
Loudness
 Speed
The speed of sound is 330 metres per second in dry air in room
temperature. Sound moves faster through liquids and solids than air, since
liquids and solids can be pushed together more. Sound cannot travel through
a vacuum, which is a space without any air or matter. The speed of sound is
affected by temperature. It travels slower at low temperatures, for example in
the stratosphere
 Frequency
An important measurement of sound is the frequency.
This is how fast the sound wave is oscillating.
Frequency is measured in hertz.
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Audible sound has frequencies between 20 Hz to 20 kHz.
Human beings can hear audible sound.
Sound waves with frequency above 20 kHz are called ultrasound waves.
Sound waves with frequency below 20 Hz are called infrasound waves.
Human beings cannot hear ultrasound waves and infrasound waves, but
some animals, like bats and dolphins, use them. Older people have an
even smaller hearing range.
• People are best at hearing sounds between 1000 Hz and 6000 Hz.
 Loudness
Loudness refers to how loud or soft a sound seems to a listener.
The loudness of sound is determined, in turn, by the intensity of
the sound waves. Intensity is a measure of the amount of energy
in sound waves. The unit of intensity is the decibel (dB).
Characteristic of Sound
#1 Sound travel
Sound waves travel through
air, water, and solid objects as
vibrations.
#2 Sound can be reflected (bounced)
Sound waves can reflect off surfaces.
We hear sound reflections as echoes. Hard smooth surfaces are
really good at reflecting sounds – this is why empty rooms
produce lots of echoes.
#3 Sound can be absorbed
Sound absorption is the loss of sound energy when sound waves
comes into contact with an absorbent material such as Fibrous materials
and other objects, as a result of which, the sound is not reflected back
into the space.
#4 Sound can be modified
Sound can be changed to alter the pitch of a sound. To be able to
modified what sound looks like when we change the pitch or
loudness.
#5 Sound is caused by vibrations
Sound is a type of energy made by vibrations. When any object
vibrates, it causes movement in the air particles. These particles
bump into the particles close to them, which makes them vibrate too
causing them to bump into more air particles.
Trivia Questions
1.Can sound travel under the water?
Yes sound can travel under the water. It moves four times faster
through water than through the air. It can travel such long
distances that whales can hear each other when they are nearly a
hundred miles apart.
2.Is there sound on the moon?
No, there is no sound in space. Sound needs something to travel
through like air or water.
3.What is the speed of Sound?
Sound travels through air at 1,120 feet (340 meters) per second.
Thank you