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- 1. 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 you can feel the vibration inside your throat.
- 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. HOW SOUND TRAVELS? Sound passes through the medium as
longitudinal waves. When the vibrations are fast you hear a high
pitch. When theyre slow, you hear a low pitch. High Pitch Low
Pitch
- 4. PRODUCTION OF SOUND 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. 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. Vibrating tuning
fork Table tennis ball Thread
- 5. LOW SOUND AND HIGH SOUND 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.
- 6. High pitch = high frequency Low pitch = low frequency
- 7. SOUND NEEDS MEDIUM TO TRAVEL Sound is a mechanical wave and
needs a medium for propagation. Sound travels through solids,
liquids and gases. Sound does not travel in vacuum. 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 vacuum. Cork Bell jar
Electric bell
- 8. AMPLITUDE OF SOUND Volume control Loudness Strength of the
wave ( measured in db decibels) Energy of the wave
- 9. DO YOU KNOW HOW DOES MUSICAL INSTRUMENT CREATE SOUND It
depends on the type of instrument. There are four types. Woodwind
String Percussion Brass
- 10. WOODWIN INSTRUMENTS Woodwinds make music by blowing on the
top of the instrument or on a reed.
- 11. STRING INSTRUMENTS Strings make music by plucking or
strumming the strings.
- 12. PERCUSSION INSTRUMENTS Percussion instruments make music by
striking, shaking or scraping them.
- 13. BRASS INSTRUMENT Brass instruments make music by buzzing
lips while blowing.
- 14. HOW DOES VIOLEIN PRODUSES SOUND? The body of the violein 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 the sound is then amplified.
- 15. HOW DOLPHINS COMMUNICATE EACH OTHER One way they do it is
by making sounds. They dont 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. Whales sing to each other. Sound travels through water
- 17. NOISE POLLUTION Sound that is unwanted or disrupts ones
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 cant see, smell,
or taste it. World Health Organization stated that Noise must be
recognized as a major threat to human well-being
- 18. 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 attacks.
- 19. 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. Loud speakers, plumbing,
boilers, generators, air conditioners, fans, and vacuum cleaners
add to the existing noise pollution.
- 20. 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.
- 21. SOLUTION FOR NOISE POLLUTION Similar to automobiles,
lubrication of the machinery and servicing should be done to
minimize noise generation. Soundproof doors and windows can be
installed to block unwanted noise from outside. Regulations should
be imposed to restrict the usage of play loudspeakers in crowded
areas and public places. Factories and industries should be located
far from the residential areas.
- 22. SOLUTION FOR NOISE POLLUTION Community development or urban
management should be done with long- term planning, along with an
aim to reduce noise pollution. Social awareness programs should be
taken up to educate the public about the causes and effects of
noise pollution.
- 23. 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
- 24. VOICE BOX OF HUMAN
- 25. Sound travels to your ear Sound The air vibrates but does
not travel from the alarm to the ear.
- 26. HUMAN EAR The outer ear called pinna collects the sound
waves. The sound waves passes through the ear canal to a thin
membrane called eardrum. The eardrum vibrates. The vibrations are
amplified by the three bones of the middle ear called hammer, anvil
and stirrup. The middle ear then transmits the sound waves to the
inner ear. In the inner ear the sound waves are converted into
electrical signals by the cochlea and sent to the brain through the
auditory nerves. The brain then interprets the signals as
sound.
- 27. Mobile phones use radio Sound - electrical signal - radio
signal - electrical signal - sound Radio signal Mobile phone
beacons In the second phone the radio signal is changed into an
electrical signal then into sound. In one phone the sound is
changed into an electrical signal then into a radio signal. Sound -
electrical signal - radio signal - electrical signal - sound
- 28. TELEPHONES The message travels through miles of wires as an
electrical signal. microphone loudspeaker electrical signal
- 29. Sound travels 4 times faster through water than through
air. There is no sound in space. Geologists use their knowledge of
how sound travels through rocks to help them find oil fields.
Whales in the ocean "sing" to each other. The sound of their song
can travel a distance of 800km. Sound moves through the air at 340m
per second. SOME INTRESTINGFACTS