HOPE THIS IS HELPFUL TO YOU !!!!!!

1. SCIENCE - SOUND
Bhavishya Gaur – 8th H

2. WHAT IS SOUND?
Sound is
 A form of energy made by vibrations.
 When an object vibrates it causes the air
particles around it to move.
 These particles bump into particles close to
them and this continues until they run out of
energy.

3. TRY THIS:
 Put your finger on your
neck and say “aah” as loud
as you can.
 Now say it as soft as you
can.
 You can not only hear the
sound, but youcan feel the
vibration inside your throat.

4. HOW SOUND TRAVELS?
 Sound passes through
the medium as
longitudinal waves.
 When the vibrations
are fast you hear a
high pitch. When
they’re slow, you
hear a low pitch.

5. HOW SOUND TRAVELS?
 Sound is produced due to the vibration of objects.
 Vibration is the rapid to and fro motion of an object.
 Eg :- The sound of human voice is produced due to the
vibration of the vocal cords.
 A stretched rubber band when plucked vibrates and
produces sound.

6. HOW SOUND TRAVELS?
 Activity :- Strike the prongs of
a tuning fork on a rubber pad
and bring it near the ear.
 We can hear a sound. If a
suspended table tennis ball is
touched with the vibrating
prong, the ball is pushed away
repeatedly. This shows that the
prong is vibrating and vibrating
objects produces sound

7.  The pitch of sound (shrillness or flatness)
depends on the frequency of vibration.
 If the frequency is high, the sound has high
pitch and if the frequency is low, the sound
has low pitch.
LOW SOUND AND HIGH SOUND

8.  High pitch = High frequency
 Low pitch = low frequency
LOW SOUND AND HIGH SOUND

9.  Sound is a mechanical wave and
needs a medium for propagation.
 Sound travels through solids, liquids
and gases. Sound does not travel in
vacuum
SOUND NEEDS MEDIUM TO TRAVEL

10. Activity:-
 Suspend an electric bell in an air tight
bell jar.
 Connect the bell jar to a vacuum pump. If
the switch is pressed, we can hear the
sound of the bell.
 If air is pumped out through the vacuum
pump, we cannot hear the sound of the
bell.
 This shows that sound needs a medium
to travel and sound cannot travel in
SOUND NEEDS MEDIUM TO TRAVEL

11.  Volume control
 Loudness
 Strength of the wave ( measured in db
“decibels”) Energy of the wave
AMPLITUDE OF SOUND

12.  It depends on the
type of instrument.
There are four
types.
 Woodwind
 String
 Percussion
 Brass
DO YOU KNOW HOW DOES
MUSICAL INSTRUMENT CREATE SOUND

13. BRASS INSTRUMENT
 Brass instruments
make music by
buzzing lips while
blowing.

14. HOW DOES VIOLIN PRODUSES
SOUND?
Sound is
 The body of the violin is a large
hollow chamber that functions as a
speaker or amplifier for vibration.
 The strings are suspended above
the body of the instrument by a
bridge, a small maple piece of
wood secured to the top of the
instrument by the tension of the
strings.
 The vibration from the strings is
transferred through the bridge to
the body of the instrument where

15. HOW DOLPHINS COMMUNICATE
EACH OTHER
 One way they do it is by making sounds. They don’t have
vocal chords like we do, but they can control muscles in their
blowholes to make different noises.
 Some of the noises they make sound like whistles and
squeaks. Some of their sounds are ultrasonic, which means
they are too high in pitch for people to even hear!
 By making all these sounds, dolphins can identify themselves
to each other.

16. NOISE POLLUTION
 Sound that is unwanted or disrupts one’s quality of life is called
as noise.
 When there is lot of noise in the environment, it is termed as
noise pollution.
 Sound becomes undesirable when it disturbs the normal
activities such as working, sleeping, and during conversations.
 It is an underrated environmental problem because of the fact
that we can’t see, smell, or taste it.
 World Health Organization stated that “Noise must be
recognized as a major threat to human well-being”

17. HEALTH EFFECTS
 According to the USEPA, there are
direct links between noise `and
health. Also, noise pollution
adversely affects the lives of
millions of people. Noise pollution
can damage physiological and
psychological health.
 High blood pressure, stress
related illness, sleep disruption,
hearing loss, and productivity loss
are the problems related to noise
pollution.
 It can also cause memory loss,
severe depression, and panic

18. SOURCES OF NOISE POLLUTION
 Transportation systems are the main source of
noise pollution in urban areas.
 Construction of buildings, highways, and streets
cause a lot of noise, due to the usage of air
compressors, bulldozers, loaders, dump trucks,
and pavement breakers.
 Industrial noise also adds to the already
unfavorable state of noise pollution.

19. SOLUTION FOR NOISE POLLUTION
 Planting bushes and trees in and around sound
generating sources is an effective solution for
noise pollution.
 Regular servicing and tuning of automobiles can
effectively reduce the noise pollution.
 Buildings can be designed with suitable noise
absorbing material for the walls, windows, and
ceilings.
 Workers should be provided with equipments
such as ear plugs and earmuffs for hearing
protection

20. HUMAN VOICE BOX
 In humans sound is produced by the voice box
or the larynx.
 The voice box is at the upper part end of the
windpipe.
 Tow vocal cords, are stretched across the
voice box or larynx in such a way that it leaves
a narrow slit between them for the passage of
air

21. VOICE BOX OF HUMAN

22. THANK-YOU!
Bhavishya Gaur – 8th H