Sound is a form of energy that propagates as mechanical waves, requiring a medium such as air, water or solid material to transmit energy. It is caused by vibrations which create pressure variations that propagate outward as a wave at the speed of sound. The speed of sound depends on factors like the density, elasticity and temperature of the medium, being fastest in solids and slowest in gases. Sound exhibits properties like reflection, refraction, diffraction and interference as it travels and interacts with surfaces and other sounds.

1. SOUND

3. Objectives:
● Determine the propagation of sound in different
mediums.
● Differentiate of the different properties of sound
waves: refraction, reflection, diffraction and
interference.

4. What is Sound?
Sound is a form of ENERGY that behaves in a predictable way
What Causes Sound?
Sound is made because of VIBRATIONS.
What are Vibrations?
These are the back-and-forth motions as a WAVE.
Waves
In physics, a wave travels through matter transferring energy from one place to
another.
Therefore…

5. SOUND is a form of energy caused by
vibration that is passed from one
point to another as a wave.
● Sound is an example of a mechanical wave and of a
longitudinal wave.
● It simply follow an orderly pattern or coherence of
motion.

6. ● It is composed of waves of compression and rarefaction in
which the human ear is sensitive. the size of a compression
indicates how much energy the sound wave has.

7. Human Hearing
sound wave
vibrates ear drum
amplified by bones
(malleus, incus,
staples)
converted to nerve
impulses in cochlea

8. Human voice uses several types of sound
production and modification of mechanisms
The vocal cords located in the in the throat
primarily produces the sound for singing and for
spoken vowels.
Sounds produced differ because of the
differences in SHAPE of the air cavities in the throat,
mouth and nasal region

9. Speed of Sound
The speed of sound is defined as the dynamic
propagation of sound waves. This depends on
the characteristics of the medium through
which the propagation takes place. Speed of
sound is used for describing the speed of
sound waves in an elastic medium.

10. Speed of Sound
1. Type of Medium -travels through liquids, solids and gas
but can’t travel through a vacuum.
2. Temperature of Medium - can also travel in lower or
higher temperature.
3. Density -sound moves well through dense materials.
4. Elasticity -sound waves move fast through elastic
materials.

11. DOPPLER EFFECT
change in wave frequency caused by a moving
wave source moving toward you - pitch sounds
higher moving away from you - pitch sounds
lower

12. Speed of Sound
Medium
In which medium does
SOUND travels the fastest?

13. Sound travels:
Fast: Gas
Faster: Liquid
Fastest: Solid

14. Solids are significantly denser than liquids or
gases. This means that the molecules are closer
to each other in solids than in liquids and in
liquids than in gases. This closeness due to
density means that they can collide very quickly.
Due to this advantage, the speed of sound in a
solid is larger than in a gas.
Speed of Sound in Solid

15. The density of a liquid is greater than of a
gas. Therefore the distances between molecules
are more in liquids than in solids but are less
than in gases. Hence the speed of sound in
liquids lies in between the speed of sound in
solids and gases.
Speed of Sound in Liquid

16. We should remember that the speed of sound
is independent of the density of the medium when
it enters a liquid or solid. Since gases expand to
fill the given space, density is quite uniform
irrespective of the type of gas. This clearly isn’t
the case with solids and liquids.
Speed of Sound in Gas

17. Speed of Sound in Vacuum
The speed of sound in a vacuum is zero meters per
second, as there are no particles present in the vacuum.
The sound waves travel in a medium when there are
particles for the propagation of these sound waves. Since
the vacuum is an empty space, there is no propagation of
sound waves.

18. Speed of Sound
Temperature
In what Temperature
does sound travel
faster?

19. Molecules at higher
temperatures have more
energy and can vibrate
faster and allow sound
waves to travel more
quickly

20. Sounds possess the
properties and the
characteristics that
are common to all
waves.

21. Properties
of Sound
A. Refraction of Sound
- change in direction, as
the wave moves from one
medium to another. It
bends or refracts as they
move through air.

22. B. Reflection of
Sound
- when a sound
wave strikes a
hard surface, it
changes its
direction and goes
back to the same
medium. Echo is
an example.

23. C. Diffraction of Sound
- sound waves bend or diffract around
corners or barriers like doors and walls.

24. D. INTERFERENCE
- the result of two or more sound
waves overlapping

25. ● Constructive
interference -the sound
waves arrive at the same
time and phase
● Destructive
interference -waves
arrive at interval and are
out of phase
Types of
Interference

26. Characteristics of Sound
1. PITCH
-highness or lowness of a sound.
a. Frequency
- number of sound waves that passes
through a point in a certain amount of
time, such as one second. -the greater
the frequency, the higher the pitch.

27. Hertz (Hz)- unit to measure frequency
and pitch
Audio frequency range -Frequency
ranging 20 Hz to 20 000 Hz -Sounds
that human ear can hear is an
example.
INFRASONICS -Frequency below 20 Hz.

28. 1. Pure tone- simplest waveform, it has
a soft, pleasant tone quality and
sinusoidal
2. Complex tone- nearly sinusoidal
Different waveforms

29. 2. LOUDNESS or INTENSITY
- description of how high or low the sound seems
to a person -determined mainly by the
amplitude of the sound wave
a. Decibel (dB)- unit used to measure sound intensity or
loudness. LOUDNESS OF SOUND IN DECIBEL

30. LOUDNESS OF
SOUND IN
DECIBELS
Sound Loudness
(dbs)
Hearing
Damage
Average
Home
40-50 - - - - - -
Loud
Music
90-100 After long
exposure
Rock
Concert
115-120 Progressiv
e
Jet
Engine
120-170 Pain

31. 3. TIMBRE
- tone color or tone quality
- used to distinguished between
two different sounds that have
the same pitch and loudness
- It helps to identify what
produced the sound

32. Basic element of music
1. Pitch- highness or lowness of the note
2. Intensity- loudness of the note
3. Rhythm- repeating pattern of beats and it keeps the
time to the music
4. Melody- series of pitches 5. Harmony- three or more
notes played together.
Characteristics of Musical Sounds Note

33. Noise
unwanted sound and a
subtle pollutant which
can threaten the Health
or well being of an
individual

34. Sound Energy Vibrations Waves
Speed of Sound
➢ Medium - Solid, Liquid, Gas,
Vacuum
➢ Temperature - Hot and Cold
Properties of
Sound Energy
➢ Refraction
➢ Reflection
➢ Diffraction
➢ Interference
Doppler Effect Hertz (Hz)- unit to measure frequency
and pitch
Decibel (dB)- unit used to measure
sound intensity or loudness
NOISE - unwanted sound