1. Properties of Sound Wave
By: Group 4
IV-St.Angela

2. properties of Sound Waves
• Reflection
• Refraction
• Diffraction
• Interference

3. •
REFLECTION

4. Reflection
* The return of sound waves from surfaces on
which they are incident.
* Reflection of sound waves off of surfaces can
lead to a phenomena called ECHOES
*When sound reflects off a special curved surface
called a parabola, it will bounce out in a straight line
no matter where it originally hits.

5. Echoes

6. • Echoes are the sound of your own voice
reflecting back to your ears.
• A sound wave will continue to bounce around
a room, or reverberate, until it has lost all its
energy.
• A wave has some of its energy absorbed by
the objects it hits.

7. Parabola

8. • Smooth walls have a tendency to direct sound
waves in a specific direction.
• Rough walls tend to diffuse sound, reflecting it
in a variety of directions.

9. Refraction

10. Refraction
Refraction is the bending of waves
when they enter a medium where
their speed is different.

11. Refraction of sound waves is most
evident in situations in which the sound
wave passes through a medium with
gradually varying properties.

12. • Sound propagates in all directions from a
point source. Normally, only that which is
initially directed toward the listener can be
heard, but refraction can bend sound
downward. Normally, only the direct
sound is received. But refraction can add
some additional sound, effectively
amplifying the sound. Natural amplifiers
can occur over cool lakes.

13. Diffraction

14. Diffraction
• The BENDING of waves around small obstacles
– The sound with longer wavelength compared to
the obstacle will sound loudest
– The amount of diffraction that occurs depends on
both the size of the obstacle and the wavelength
of the sound.
The SPREADING OUT of waves beyond small
openings
- the smaller the gap size then Maximum diffraction
occurs and the sounds spreads out greatly

16. Spreading Out of Waves
• Bigger Gap size Smaller Gap size

17. Interference

18. • Is the phenomenon that occurs when two
waves meet while traveling along the same
medium.
• The interference of waves causes the medium
to take on a shape that results from the net
effect of the two individual waves upon the
particles of the medium.

19. Constructive Interferene
• Occurs at any location along the medium where the two
interfering waves have a displacement in the same
direction.
• Both waves have an upward displacement;
consequently, the medium has an upward displacement
that is greater than the displacement of the two
interfering pulses.
• Observed at any location where the two interfering
waves are displaced upward. But it is also observed when
both interfering waves are displaced downward.

22. Principle of superposition
• When two waves interfere, the resulting
displacement of the medium at any
location is the algebraic sum of the
displacements of the individual waves at
that same location.

23. RESONANCE

24. • when one object vibrating at the same natural frequency
of a second object forces that second object into
vibrational motion.
• The word resonance comes from Latin and means to
"resound" - to sound out together with a loud sound.
• It is a common cause of sound production in musical
instruments
• .

25. • *Another example are the woodwind instruments
When air is blown through the reed, the reed
vibrates producing turbulence with a range of
vibrational frequencies , the result of resonance is a
big vibration, the reed and air column sound out
together to produce a loud sound.
• *Brass instruments involve the blowing of air into a
mouthpiece. The vibrations of the lips against the
mouthpiece produce a range of frequencies. One of
the frequencies in the range of frequencies matches
one of the natural frequencies of the air column
inside of the brass instrument. This forces the air
inside of the column into resonance vibrations. The
result of resonance is always a big vibration - that
is, a loud sound.

26. Doppler Effect

27. • It is an effect produced by a moving source
of sound wave
• There is an upward shift in the frequency
for the observer being approached by the
source
• There is a downward shift for the observer
from whom the source is receding

28. • The Man
• - Hears the
sound of the
shorter
wavelengths
• - Higher
frequency
• - Higher pitch
• The Woman
• - Hears the
sound of the
longer
wavelengths
• - Lower
frequency
• - Lower pitch

29. END