SOUND DONE BY;

R.MANSHI AND LOGANAYAKI

8th ‘A’

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.

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.

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.

High Pitch Low Pitch

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.

Vibratingtuning fork

Table tennis ball

Thread

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.

• High pitch = high frequency

• Low pitch = low frequency

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

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

DO YOU KNOW HOW DOES MUSICAL INSTRUMENT CREATE SOUND

• It depends on the type of instrument. There are four types.

– Woodwind– String– Percussion– Brass

WOODWIN INSTRUMENTS

• Woodwinds make music by blowing on the top of the instrument or on a reed.

Flute

Oboe

Clarinet

Bassoon

Piccolo

STRING INSTRUMENTS• Strings make music by plucking or

strumming the strings.

Violin

Cello Guitar

ElectricGuitar

Harp

PERCUSSION INSTRUMENTS

• Percussion instruments make music by striking, shaking or scraping them.

Drum

Tambourine Piano

Cymbals Xylophone Maracas

BRASS INSTRUMENT• Brass instruments make music by buzzing

lips while blowing.

French Horn

Trombone

Tuba

Trumpet

HOW DOES VIOLIN PRODUSES SOUND?

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 the sound is then amplified.

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.

Whales sing to each other.

Sound travels through water

NOISE POLLUTIONSound 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”

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.

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.

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.

• 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.

• 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.

HUMAN VOICE BOXIn 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

VOICE BOX OF HUMAN

Sound travels to your ear

Sound

The air vibrates but does not travel from the alarm to the ear.

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.

HUMAN EAR

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

TELEPHONES

The message travels through miles of wires as an electrical signal.

microphone

loudspeaker

electrical signal

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 INTRUSTING FACTS

THE END