Sound

Question 1

What is sound?

Answer 1

Sound is a form of wave or mechanical energy which is produced by vibration of objects.

Question 2

What is a vibration?

Answer 2

Vibration is the to and fro motion of an object.

Question 3

How is sound produced in humans? what is the structure of it ? How does it work ? Where is it located ?

Answer 3

In humans, the sound is produced by the voice box or the larynx. It is situated at the upper end of the windpipe. Two 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. When the lungs force air through the slit, the vocal cords vibrate, producing sound.

Question 4

What decides the quality of voice produced by humans?

Answer 4

When the vocal cords are tight and thin, the quality of voice is different from that when they are loose and thick.

Question 5

Name the length of vocal cords in men, women and children.

Answer 5

Men - 20 mm
Women - 15 mm
Children - not mentioned but smaller.

Question 6

Why sound can’t travel in vaccum?

Answer 6

Sound can’t travel in a vaccum as there is no air in a vaccum making it not capable of transfer. Moreover a sound needs a medium to travel may it be gas, liquid or solid.

Question 7

Arrange the medium of sound to travel in ascending order in terms of fastness.

Answer 7

Gas<Liquid<Solid

Question 8

What are audible and inaudible sounds? What are their names and what is their range ?

Answer 8

Human ear can only hear sounds that are in the range of 20 Hz to 20 kHz. The sounds which we can hear are audible sounds and those we can’t are inaudible. The sounds which are under 20 Hz are called infrasonic sounds ex: rhinoceros, whales and elephants and those which are above 20 kHz are called ultrasonic sound ex : dogs, whales, bats and dolphins.

Question 9

How does sound travel?

Answer 9

Sound travels in waves which is carried by a medium in all directions.

Question 10

How do we hear ?

Answer 10

The shape of the outer part ( also called pinna ) of the ear is like a funnel. Through it sound travels down a canal called middle ear. At the middle ear there is a eardrum which catches the waves and transforms it to vibrations. These vibrations then get to the inner ear ( cochlea ) and travels through water and hair present there. Then the hearing nerve transports them to the brain. This process is so fast that we are not aware of it.

Question 11

What is a eardrum?

Answer 11

The eardrum is like a thin stretched rubber membrane (sheet) which is present in the middle ear, it transforms the sound waves into vibrations and passes them down to the inner ear.

Question 12

What is oscillatory motion? What is an oscillation?

Answer 12

The to and fro motion of an object is called oscillatory motion. The repeated motion of an object in which it travels from a point and returns to it is called an oscillation.

Question 13

What is frequency?

Answer 13

The number of oscillations per second is called the frequency of oscillation frequency is expressed in hertz its symbol is Hz.

Question 14

What is amplitude?

Answer 14

Complete your is the maximum or highest displacement of air molecules from its mean position in a sound wave.

Question 15

What is loudness and on which property is it depended upon?

Answer 15

Loudness is the characteristic of sound which tells us whether the amplitude of vibration is large or small. It depends upon amplitude of the sound wave.

Question 16

What is shrillness or pitch of a sound?

Answer 16

It is the characteristic of sound which tells us whether the frequency of vibration is higher or lower. It depends upon frequency of a sound wave. For example a drum vibrates with low frequency therefore, it produces a low-pitch sound. On the other hand, a whistle has a high frequency and therefore, produces a sound of higher-pitch. The one who produces big sound is said to be of low-pitch and one who has thinner and small voice is said to be off high- pitch. Man is the lowest pitch as his voice is big and woman is of high pitch as of thin voice.

Question 17

What is difference between noise and music?

Answer 17

Noise are the unpleasant sounds which have irregular frequency and amplitude. Where is music is the sound which we enjoy and are made from musical instruments. Music can become noise if it is played in higher volumes. Example of noise is horns of vehicles construction site works, etc where is example of music is sound of guitar, sitar or any other musical instrument.

Question 18

What is noise pollution what can it do to human health?

Answer 18

Noise pollution is the presence of excessive or unwanted sounds in the environment. Mere sources of noise pollution are from vehicles, explosion including bursting of crackers, machines, loudspeakers, etc. Noise pollution may lead to many health related problems including lack of sleep, hypertension (high blood pressure), anxiety and many more health disorders. A person who is exposed to a loud sound continuously may get temporary or even permanent impairment of hearing.

Question 19

How can we prevent noise pollution?

Answer 19

To control noise, we must control the sources of noise. Silencing devices must be installed in aircraft engines, transport vehicles, industrial machines, and Home appliances. All noisy operations must be conducted away from any residential area, noise producing industries should be set up away from such areas. Use of automobile horns should be minimised. TV and music system should be run at low volumes. Trees must be planted along the roads and around buildings to cut down on the sounds reaching the residents.

Question 20

Write a short note on hearing impairment.

Answer 20

Total hearing impairment is usually from birth itself. Partial hearing is a result of a disease, injury or old-age.By learning sign language, such people can communicate and learn. Technological devices have made living easy for such people.