SOUND WAVES
are the result of
VIBRATIONS
A SOUND WAVE is a
LONGITUDINAL WAVE but it
is drawn as a transverse wave
Since a sound
wave consists of a
repeating pattern
of high pressure
and low pressure
regions moving
through a
medium, it is
sometimes
referred to as a
pressure wave
Sound is a
MECHANICAL WAVE

Sound requires a medium
 Sound can travel in a solid, liquid, or gas
The Speed of SOUND in AIR
The speed of sound 331 m/s at 00C
 The speed of sound increases about 0.6 m/s for
each 0C rise in temperature

vT = v0 + 0.6T

Sound travels faster in liquids and fastest in solids
than in air (a gas) because the molecules are closer
together
The Frequency
of a SOUND WAVE

Represents the PITCH or a NOTE on
a MUSICAL SCALE
Frequencies of Sound
The human ear is capable of detecting sound waves
between 20 Hz to 20 000 Hz.
 Any sound with a frequency below the audible range of
hearing is an infrasound and any sound with a
frequency above the audible range of hearing is known
as an ultrasound.
 Dogs can detect frequencies between 50 Hz and 45 000
Hz.
 Bats, who must rely on sound echolocation for
navigation and hunting, can detect frequencies as high
as 120 000 Hz.
 Dolphins can detect frequencies as high as 200 000 Hz.
 An elephant possesses the unusual ability to detect
infrasound, having an audible range from
approximately 5 Hz to approximately 10 000 Hz.

The AMPLITUDE
of a SOUND WAVE

Represents the LOUDNESS of the
sound
LOUDNESS in Decibels
0
10
20
30
50
60
80
90
110
120
170
Silence
Heartbeat
Whisper
Soft piano
Soft talking
Conversation
Street traffic
Food blender
Thunder
Painful sounds
Jet engine
Resonance

Resonance occurs when
two interconnected objects
share the same frequency.

Resonance occurs when
one object vibrating at the
same natural frequency of
a second object forces that
second object to vibrate.
The Doppler Effect
The Doppler Effect