The document discusses the nature and properties of sound waves. It covers topics such as: - Sound is a mechanical longitudinal wave that consists of compressions and rarefactions, transferring energy through a medium. - The frequency and intensity of sound waves can be measured, and the speed of sound depends on the properties of the transmitting medium. - Sound waves are also discussed in the context of medical applications like hearing, sonar, and ultrasonic imaging techniques.

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Dr. Mohammed I. Raslan
Sound Waves
IN THIS
CHAPTER
NATURE OF SOUND WAVES
PROPERTIES OF SOUND
BEHAVIOR OF SOUND WAVES
HOW DO WE HEAR SOUNDS
APPLICATIONS IN MEDICINE

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SECTION 1
Nature of Sound Waves
A wave is:
A disturbance transporting
energy from one location to
another location.
SOUND IS A
MECHANICAL
WAVE

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Nature of Sound Waves
Sound wave is transported
through a medium via the
mechanism of:
Particle‐to‐particle interaction,
Sound is a mechanical wave.
SOUND IS A
MECHANICAL
WAVE
Nature of Sound Waves
Mechanical waves:
Require a medium
Cannot travel through space or
vacuum.
Electromagnetic waves
Do not require a medium
Capable of traveling through a
vacuum
SOUND IS A
MECHANICAL
WAVE

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Nature of Sound Waves
LongitudinalWaves
The motion of the particles of
the medium is in a direction that
is parallel to the direction of
energy transport.
SOUND IS A
LONGITUDINAL
WAVE
Nature of Sound Waves
The result of such longitudinal
vibrations is the creation of
compressions and rarefactions
SOUND IS A
LONGITUDINAL
WAVE

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Nature of Sound Waves
Compression
Regions in the air where the air
particles are compressed
together (High Pressure)
Rarefaction
Regions where the air particles
are spread apart (Low Pressure)
SOUND IS A
LONGITUDINAL
WAVE
Nature of Sound Waves
Sound wave consists of a repeating
pattern of high‐pressure and low‐
pressure regions.
It is sometimes referred to as a
pressure wave.
The human ear can detect
fluctuations in pressure
SOUND IS A
PRESSURE
WAVES

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Nature of Sound Waves
SOUND IS A
PRESSURE
WAVES
PressureWaves
SECTION 2

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Properties of Sound
It is defined as the number of
complete cycles per second
Refers to how often the particles of
the medium vibrate when a wave
passes through the medium.
The human ear can detect from 20
Hz to 20 000 Hz.
FREQUENCY
Properties of Sound
Infrasound
A frequency below the audible
range of hearing
(i.e., less than 20 Hz)
Ultrasound
A frequency above the audible
range of hearing
(i.e., more than 20 000 Hz)
FREQUENCY

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Properties of Sound
Intensity of sound
The amount of energy that is
transported past a given area of
the medium per unit of time.
Inverse square law
The intensity varies inversely
with the square of the distance
from the source
INTENSITY
Properties of Sound
TheThreshold of Hearing:
The weakest sound that the typical
human ear can detect has an
intensity of 1 x 10‐12 J/m2.sec
The most intense sound that the
ear can safely detect is more than
one billion times more intense
than the threshold of hearing
INTENSITY

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Properties of Sound
The speed of sound in air
The distance travelled by the
wave per unit of time.
Speed (how fast...)
Frequency (how often...)
SPEED
Properties of Sound
Factors Affecting Wave Speed
The speed of any wave depends
upon the properties of the
medium.
Inertial properties
Elastic properties
SPEED

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Properties of Sound
Elastic properties
The tendency of a material to
maintain its shape whenever a
force is applied to it.
V (solid) >V (Liquid) >V (Gas)
SPEED
Properties of Sound
Inertial Properties
Material's resistance to changes in
its state of motion.
The density of a medium is an
example of an inertial property
The greater the density of the
medium, the less responsive it will
be
SPEED

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Properties of Sound
Even though the inertial factor
may favor gases, the elastic
factor has a greater influence on
the speed (v) of a wave
SPEED
SECTION 3

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Behavior of Sound Waves
Doppler effect
Change of frequency observed
whenever the source of waves is
moving with respect to an
observer.
DOPPLER
EFFECT
Behavior of Sound Waves
DOPPLER
EFFECT

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Behavior of Sound Waves
Frequency Increase
Source and observer are
approaching
Frequency Decrease
Source and observer are
receding
DOPPLER
EFFECT
Behavior of Sound Waves
Shockwaves and sonic booms
SHOCKWAVES
AND
SONIC‐BOOMS

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Behavior of Sound Waves
SHOCKWAVES
AND
SONIC‐BOOMS
Behavior of Sound Waves
Shockwaves and sonic booms
A sonic boom occurs as the result
of the piling up of compressions
These compressions pile up and
interfere to produce a very high‐
pressure zone.
SHOCKWAVES
AND
SONIC‐BOOMS

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SECTION 4
Applications of Sound
HEARING
Hearing Sounds andVoices

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Applications of Sound
SOund Navigation And Ranging
Sonar is emitting pulses of
sounds and listening for echoes.
Sonar may be used to determine
distance andVelocity
SONAR
Applications of Sound
ULTRASONIC
IMAGING
Ultrasonic
Imaging
Time of
Flight
(Echography)
Doppler
Effect

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Applications of Sound
ULTRASONIC
IMAGING
ECHOGRAPHY
Echography
Applications of Sound
ULTRASONIC
IMAGING
ECHOGRAPHY
Echography

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Applications of Sound
Doppler Ultrasonography
Employ the Doppler effect to
assess whether structures
(usually blood) are moving
towards or away from the probe,
and its relative velocity
ULTRASONIC
IMAGING
(DOPPLER)
Applications of Sound
ULTRASONIC
IMAGING
(DOPPLER)

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Applications of Sound
ULTRASONIC
IMAGING
(DOPPLER)
Applications of Sound
Maxillofacial Bone Healing
Low‐intensity ultrasound
Creates internal heating of
localized tissue without harmful
effects on nearby tissue
Reduce the healing time of fresh
fractures up to 38%
ULTRASONIC
HEALING

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Quick Quiz …
If you are a genius, answer this:
How to determine the distance
to a lightening cloud?
QUIZ