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Sound CBSE Class 8 Science Revision Notes Chapter 13

What is sound.

A sound is a form of energy that is produced when air molecules vibrate in a particular pattern called waves. Hence, the sound is a wave.

Vibration can be described as a back and forth motion of an object.

Depending upon the vibrations, a sound is produced. Sound cannot be produced without any vibration.

Figure 1 Production of Sound through Vibrations

Figure 2 Different instruments produce different sounds

How do humans produce sound?

Human beings have a voice box or larynx which is present in their throat on the upper side of the windpipe.

The larynx has two vocal cords which have a narrow slit between them so that air can pass through it.

As the lungs throw the air out of the windpipe, it passes through the slit and hence allows the production of sound as the vocal cords start vibrating.

The vocal cord muscles also play a role in the production of sound.

Their thickness and tightness describe the quality or type of the voice a person has.

The vocal cords in males are of length 20 mm and females have 15mm long vocal cords. Children, on the other hand, have very short length vocal cords. Hence, the voices, their quality and their type are always different in women, men and children.

Figure 3 Larynx or Voice box

Propagation of sound through a medium

Sound always requires a medium to travel from the source of its production to the receiver end. Different mediums of propagation of sound are air, liquid and solids.

Sound cannot travel through a vacuum as it lacks any medium of transmission.

Figure 4 Sound Waves

How sound travels in a medium?

Sound needs some vibration of molecules to travel.

Solids, liquids and gases all have molecules present in them which allow the propagation of sound.

These molecules or particles in solids, liquids and gases are packed in varied ways.

Solids have tightly packed particles in them and hence they allow fast propagation of sound through them as the vibrations can be carried easily from one particle to another.

Liquids have slightly loosely packed particles and hence it takes a little time for sound to travel in water or through a liquid.

Gases have completely loosely packed particles and hence sound takes the most time in travelling through the air.

How do we hear?

We know that sounds are produced as waves in the air or any other medium.

As these sound waves travel to our ears they convert them into electrical signals or messages that our brain can understand.

Our ears have a special structure that allows this function.

There are three major parts of the human ear:

Figure 5 The Human Ear

The outer ear (Pinna): It catches the sound waves and forwards them to the next part of the ear, that is, the middle ear.

The middle ear : It converts the sound waves into vibrations that then travel to the inner ear. It can do this with the help of the eardrum. The eardrum is a thin rubber-like sheet present in the Middle ear. As the sound waves reach the eardrum, it vibrates and these vibrations propagate to the inner ear.

The inner ear (cochlea): It receives the vibrations sent by the eardrum. It contains a liquid substance and the vibrations that enter the inner ear moves through this liquid. There are tiny hairs present inside the inner ear that turn these vibrations into signals for the brain and pass them to the brain through the hearing nerve. As the brain receives the signal it interprets the sound. However, this whole process is so quick that we cannot notice it.

Frequency, Time Period and Amplitude of a Sound

Figure 6 Displacement of Particles by Production of Sound and Representation of A Sound Wave

The loudness of a sound

The loudness of a sound depends upon the amplitude of the sound.

The higher the amplitude, the higher is the displacement of the particles and the higher is the loudness of the sound.

The loudness of the sound is directly proportional to the square of its amplitude.

The SI unit for measuring the loudness of a sound in decibels (dB).

Pitch of the sound

Every person has a different sound quality.

Also, every musical instrument vibrates to produce a different kind of sound. This quality of sound is characterized by its Different quality of sounds may have same pitch and loudness.

The pitch of a sound depends upon the frequency of the sound wave.

The pitch would be higher if the frequency of the sound is high.

Different organisms and objects have different type of sound because of varied pitch:

Figure 12 Loudness and Pitch of a Sound

How Loudness and Pitch are different from each other?

Audible and inaudible sounds.

Sounds that can be heard by human ears are called audible sounds . The range of audible sounds is from 20 Hz to 20 KHz.

Sounds that cannot be heard by human ears are called inaudible sound . Any sounds having a frequency less than 20 Hz or greater than 20 KHz are categorized as inaudible sounds.

Figure 15 Loudness of Sound from various Sources

The inaudible sounds can be divided into two categories as infrasound and ultrasound.

Figure 16 Infrasound and Ultrasound

Noise and Music

Noise can be regarded as an unpleasant sound. Noise consists of sound waves of varied frequencies which have no particular periodic pattern of repetition. Therefore, noise is regarded as a mixture of sound waves with irregular frequencies.

Music , on the other hand, is a pleasant sound that has a clear pitch. Musical sound can be created by arranging and combining different sounds in a particular order. The frequencies of a musical sound are harmonious in nature.

Figure 17 Noise And Music

Noise pollution

Noise pollution can be defined as the presence of undesirable and unpleasant sounds in the earth's environment.

Human beings can bear sounds ranging up to 85 decibels only. Above that, any noise can damage our hearing power.

Generally, any sound that has a frequency of more than 30 dB is considered noise.

The unwanted noise causes an adverse effect on the health of the organisms present on the earth.

According to the World Health Organization, the maximum sound limit that is ideal for cities is 45 dB only.

However, it has been found that the sound range in many big cities of the world lies up to 90 dB.

Hence noise pollution is common in many cities today and even rural areas to a great extent.

Figure 18 Noise Pollution

Causes of noise pollution

Transport noise: The sound of the traffic on roads, railways and aircraft leads to noise pollution. As the number of vehicles such as cars, motorcycles, buses and trucks is increasing in the cities, especially the Metropolitans, noise pollution is extremely high there.

Industrial noise: Industries, factories and other commercial businesses cause high-intensity sounds that pollute the environment.

Neighbourhood noise : The noise from the radios, televisions, air conditioners, coolers, kitchen applications and other electrical appliances used in houses lead to noise. Not only this, commercialization around the residential areas often leads to unwanted sounds due to small-scale industries such as printing, car repairing etc.

Construction noise: Construction of houses, industries and various architectures also lead to sound pollution.

Political activities: Noise pollution is also created due to the rallies and demonstrations conducted by various political parties in cities and rural areas.

Bursting of crackers and fireworks: People burst crackers on several occasions such as festivals and ceremonies that lead to sound pollution in the neighbourhoods.

Natural sounds: The environment of the earth also sometimes leads to unpleasant sounds due to lightning, thunderstorms, earthquakes, volcanic eruptions, sounds of various animals etc.

Figure 19 The Noise Thermometer

Effects of Noise Pollution

Excessive noise in the surroundings can lead to serious health problems such as hypertension, lack of sleep or insomnia, anxiety, lack of memory, stress, irritation and even nervous breakdown.

It can lead to temporary or permanent hearing loss in human beings as well as animals.

Excessive noise leads to increased blood pressure. It increases cholesterol levels in the blood and therefore increases the chances of cardiovascular diseases in a person.

If sound intensity is more than 180 dB it can lead to the death of a person.

Noise pollution also leads to a decrease in the production of digestive juices by our body.

It can affect animals as well and can lead to their death and loss of habitats. Excessive noise decreases a person's ability to concentrate especially on children and they are unable to concentrate well on their studies due to neighbourhood noises.

Unwanted sounds in the environment can hinder the animals from finding their prey or their direction of motion.

Prevention of Noise Pollution

Factories and other industries should be set up at a distance from residential areas.

Silencing devices should be incorporated into heavy vehicles such as aircraft, industrial equipment, machinery and other home appliances.

We should always play television, radio and other music systems at a low sound so that it does not harm the neighbourhood.

Use of horns should be minimized especially near public places such as hospitals, religious places and schools.

Soundproofing systems should be installed in industries, party halls and other buildings that produce a high amount of unwanted sounds.

Trees should be planted in huge numbers as they can absorb unwanted noise from the environment.

People who work in noisy conditions such as industries and mines should be provided earplugs to protect their ears.

People should be made aware of noise pollution its adverse effects so that they can take an active involvement in preventing it.

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Chapter 13 Class 8 - Sound

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Get NCERT Solutions, Extra Questions, Worksheets, and Notes of Chapter 13 Class 8 Sound. Teachoo also provides solutions of all Maths and Science  NCERT Questions with explanation of Concepts.

In this chapter, we will study

What is Sound ?

How is sound produced ?

Different Musical Instruments and how sound is produced in them

What is Medium of Sound? In which medium does sound travel?

Amplitude, Frequency and Time Period of Sound

Difference between Frequency and Amplitude

How is sound produced by Humans

How do we hear sounds ?

What do you mean by Noise and Music?  

What is the difference between Noise and Music

What is Noise Pollution ?

What are the c auses and effects of Noise Pollution

How to reduce Noise Pollution ?

What is Hearing Impairment?

What are Audible and Inaudible Sounds

What are Ultrasonic Sounds ?

What are the different methods of producing sound ?

When we hear a sound, does any part of our body vibrate ? Name the part.

Does any part of the body vibrate when we speak ? Name the part.

Why is the voice of men, women and children different ?

In which medium sound travels more faster - Water, Glass, Air, Vacuum. Why?

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NCERT Solutions for Class 8 Science Chapter 13 Sound

Chapter 13 Sound Class 8 Science NCERT Solutions

Class 8 science chapter 12 friction ncert questions and answers - topics, chapter 13 sound ncert solutions for class 8 science  - notes, chapter 13 sound class 8 science questions and answers - mcq questions with answers, contact form.

Living Science 2019 2020 Solutions for Class 8 Science Chapter 13 - Sound

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Living Science 2019 2020 Solutions for Class 8 Science Chapter 13 Sound are provided here with simple step-by-step explanations. These solutions for Sound are extremely popular among class 8 students for Science Sound Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Living Science 2019 2020 Book of class 8 Science Chapter 13 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Living Science 2019 2020 Solutions. All Living Science 2019 2020 Solutions for class 8 Science are prepared by experts and are 100% accurate.

Page No 174:

Question 1:.

Can sound produced on the moon travel to the earth? Give reasons.

Sound waves are longitudinal waves which require medium to travel from one place to another. As the moon does not have any kind of atmosphere, so without any medium the sound waves produced will not be able to travel anywhere. Hence, they will never reach the earth. 

Question 2:

Sound is produced when a body undergoes to-and-fro movement. However, no sound is produced when a person waves his/her hand. Why?

The minimum frequency required to hear a sound by humans is 20 Hz. Which means 20 vibrations per second. By waving his hand, a person can not produce 20 vibrations in a single second. Hence, no sound is produced when a person waves his/her hand.

Question 3:

Sound is produced by vibration. To detect sound, some part in our ear should also vibrate when sound strikes it. Which part of the ear is this?

It is called Eardrum. When a sound with a certain frequency strikes our eardrum present inside our ear, it starts vibrating with the same frequency as of the sound wave. That's how we are able to listen to any sound. 

Question 4:

What travels faster- sound or light? Which observation in daily life supports this?

Speed of the light is much higher than the speed of the sound. In normal conditions, the speed of the sound in air is just 332 m/s, but the speed of the light is 3 × 10 8 m/s. We can also observe this difference in our daily life during the phenomenon of lightning. When lightning occurs in the sky, the sound of the lightning comes after, but before we are able to see it in the sky. This proves that light waves travel faster and reach to us first and sound waves are slow, so we hear the sound of lightning later.

Question 5:

In which medium is the speed of sound maximum- air, water or steel?

When a sound wave travels in a medium, it creates a disturbance in the particles of the medium. Every particle passes this disturbance to the adjacent particle and that's how a sound wave moves through a medium. Speed of the sound is maximum in solids as the molecules in the solid medium are tightly packed together as compared to liquids or gases, allowing sound waves to travel faster. Hence, in the given case, the speed of the sound would be maximum in steel. 

Page No 177:

Sound is produced in our vocal cords. What is the difference in the vocal cords of men and women?

Vocal cords of women are shorter than the vocal cords of men, that's why the frequency of the sound produced by women is higher and have a high pitch.

What is the difference between the sound produced by regular and irregular vibrations?

When a sound is produced by regular vibrations, it is more uniform and melody in nature. e.g. Music generated by a muscial instrument is produced due to regular vibrations. On the other hand, when a sound is produced by irregular vibrations, it is unpleasant and mostly noisy in nature. e.g. Sound produced due to racing of a motorbike is due to irregular vibrations. 

Name two of each of the following. a. Musical instruments that produce sound by vibration of a stretched string b. Musical instruments that produce sound by vibration of a stretched skin c. Musical instruments that produce sound by vibration of an air column

(a) The musical instrument which produces sound by the vibration of a stretched string is Guitar. (b) A tabla is a musical instrument in which sound is produced due to vibrations of a stretched skin. (c) In a flute, Sound is produced by vibrations of an air column.

Only noise produces noise pollution. Do you agree? Give reasons.

Not just the noise but sometimes even loud music is disturbing and causes noise pollution. 

Page No 178:

Which of the following is true for an oscillating pendulum of fixed length? (a) Frequency depends on amplitude of oscillation. (b) Frequency and time-period are not related. (c) Time-period depends on amplitude of oscillation. (d) Frequency and time-period do not depend on amplitude of oscillation.

(d) Frequency and time-period do not depend on amplitude of oscillation. Frequency is inversely related to time-period and time-period does not depend on amplitude.

The quality of sound produced by a tuning fork is different from that produced by a musical instrument because of difference in (a) amplitude (b) frequency (c) harmonics (d) none of these

(c) harmonics Tuning fork and musical instruments will produce sounds of different harmonics and loudness.

Page No 179:

Sound can travel through (a) solids only (b) liquids only (c) gases only (d) all of these

(d) all of these Sound travels through the vibrations of molecules and molecules are present in all solids, liquids and gases.

An object vibrates with a frequency of 15 hertz. Which of the following is true? (a) It produces sound that we can hear. (b) It does not produce sound. (c) It produces sound that we cannot hear. (d) It produces sound that we can hear if we strain our ears.

(c) It produces sound that we cannot hear. Humans can hear sounds in the frequency range 20Hz - 20000Hz.

In which medium does sound travel fastest? (a) air (b) water (c) steel (d) vacuum

(c) steel The molecules of steel are much more closely packed compared to that of air, water and vacuum. So, molecular vibrations pass quite quickly in steel. Consequently, sound travels fastest in steel.

Question 6:

Which of the following characteristics of sound depends on the amplitude of vibrations? (a) speed (b) pitch (c) loudness (d) quality

(c) loudness Loudness of sound depends on the amplitude of vibrations.

Question 7:

Sound of frequency 320 Hz is of lower pitch than sound of frequency (a) 10 Hz (b) 180 Hz (c) 256 Hz (d) 512 Hz

(d) 512 Hz Higher the frequency, higher is the pitch of sound.

Question 8:

Which of the following frequencies produces sound that is audible? (a) 5 Hz (b) 15 Hz (c) 500 Hz (d) 50,000 Hz

(c) 500 Hz We can hear sound in the frequency range of 20 - 20000 Hz.

Question 9:

Which of these is expected to be the best absorber of sound? (a) iron (b) wood (c) wool (d) cemented wall

Wool is the best absorber of sound among the given options.

Sound is produced by __________.

Sound is produced by vibrations .

Name the instrument used in the laboratory to produce sound of a fixed frequency.

Tuning fork is used in the laboratory to produce sound of a fixed frequency.

What does loudness of sound depend on?

Loudness of sound depends on the amplitude of vibration. Higher the amplitude of vibration, louder is the sound produced.

Give the term for 'number of vibrations per second'.

'Frequency' is the term for 'number of vibrations per second'.

Frequency is measured in __________.

Frequency is measured in hertz (Hz) .

The pitch of sound depends on the time period of vibration. Is it true or false?

Yes, the pitch of sound depends on the time period of vibration.

In general, which sound has greater frequency−a bird singing or a man singing?

The sound of a singing bird has higher frequency than that of a singing man due to higher pitch of  the bird's song.

Most vibrating objects generate sound of several frequencies simultaneously. Is it true or false?

It's true that most vibrating objects generate sound of several frequencies simultaneously.

The quality of two sounds with the same fundamental frequency differs because of the number and relative loudness of the __________

The quality of two sounds with the same fundamental frequency differs because of the number and relative loudness of the harmonics produced .

Question 10:

The sound produced by a tuning fork has no harmonics. Is it true or false?

False, a tuning fork produces harmonics that are very soft and so, barely audible.

Question 11:

Flute is a __________ instrument.

Flute is a wind instrument.

Question 12:

The pitch of the sound produced by a guitar can be altered by reducing the vibrating length of the guitar string. Is it true or false?

It's true that the pitch of the sound produced by a guitar can be altered by reducing the vibrating length of the guitar string.

Question 13:

What is the name given to the sound produced by irregular vibrations?

The sound produced by irregular vibrations is called noise.

Question 14:

The vibrations in air are picked up by the __________ ear.

The vibrations in air are picked up by the outer ear.

Question 15:

What travels faster−light or sound?

Light travels faster than sound.

Question 16:

The two kinds of sound that we cannot hear are __________ and __________.

The two kinds of sound that we cannot hear are infrasonic and ultrasonic .

Question 17:

A soft board will ___________ (reflect/absorb) most of the sound falling on it.

A soft board will absorb most of the sound falling on it.

Question 18:

What is the unit in which loudness of sound is measured?

Loudness of sound is measured in decibel (dB).

Question 19:

Prolonged exposure to noise louder than __________ dB can lead to permanent hearing damage.

Prolonged exposure to noise louder than 70 dB can lead to permanent hearing damage.

Question 20:

Which surfaces reflect sound better−hard or soft?

Hard surfaces reflect sound better than soft surfaces.

Page No 180:

How is sound produced?

Sound is produced by vibration. For example, when a guitar string is plucked, sound is produced due to vibrations produced in the string.

Distinguish between infrasonics and ultrasonics.

What do you mean by time period of a vibrating object?

The time taken by an object to complete one oscillation is called time period of the vibrating object.

What is the 'amplitude' of a vibrating object?

Amplitude is the distance covered by a vibrating object from its mean/zero position.

What is the 'frequency' of a vibrating object? How is it related to shrillness of sound?

Number of oscillations completed by a vibrating object per second is called frequency. Shrillness of sound is directly dependent on frequency. Higher the frequency of vibration more is the shrillness of sound.

Why do women have shriller voices than men?

Women have shriller voices than men because the sound produced by women is of higher frequency than that produced by men.

How does loudness of sound depend on amplitude? If the amplitude is tripled, by how much does loudness increase?

Loudness of sound is proportional to the square of amplitude. If the amplitude is tripled, the loudness increases by nine times.

Ramesh measured the time gap between lightning and thunder to be 3 seconds. Assuming light covers the distance instantly, what is the distance of the clouds from Ramesh?

As light covers the distance instantly, the time gap is the time taken by sound to reach Ramesh from its point of origin. Now, speed of sound in air = 340 m/s Time gap = time taken to travel = 3 s Distance between Ramesh and the clouds = (340 m/s)  × (3 s)                                                               = 1020 m .

Why can an echo not be heard if you stand 10 m away from a wall and shout facing it?

We cannot hear the echo because the time difference between the original sound and reflected sound will be less than 1/10 th of a second. So, we are not able to distinguish between the two sounds.

How is sound produced in our throat?

Sound, in our throat is produced in the larynx by the vibration of two vocal cords when air passes through the opening between the vocal cords.

Name the three types of musical instruments. How is sound produced in each type?

The three types of musical instruments are:

• Stringed instruments: They produce sounds using vibrations generated in metal wires fixed at both ends. For example: guitar.
• Wind instruments: They produce sounds using vibrations in an air column trapped in a hollow structure. For example: flute.
• Percussion instruments: They produce sounds using vibrations in a stretched membrane to produce sound. For example: drum.

What do you mean by noise pollution? What are the main causes of noise pollution?

Any sound produced by irregular vibrations is called noise. Too much noise in our surroundings is harmful to us and is called noise pollution. Loud music, traffic on roads, machines in factories, mixers and grinders, etc. are major causes of noise pollution.

List four ill effects of noise pollution.

Four ill effects of noise pollution are:

• Exposure to sudden high noise level (e.g. explosion) can cause permanent hearing loss due to rupture of the ear drum.
• Prolonged exposure to noise of volume higher than 70 dB can cause permanent hearing loss.
• High noise can lead to nervous tension and increase in blood pressure.
• Noise pollution can lead to sleep deprivation and headaches.

List three methods of controlling noise pollution.

Three methods of controlling noise pollution are:

• Reducing noise emissions by developing low-noise products, such as better silencers for automobiles.
• Controlling recreational noise, such as those of loudspeakers.
• Making screens or enclosures around machinery to obstruct the path of noise.

Explain quality of sound. How is it determined?

Quality of sound is the characteristic that allows us to distinguish sounds from two different sources even though the sound produced by them has same frequency and loudness. This happens because with every single frequency, called fundamental frequency, many other frequencies, known as harmonics, are also generated with differing loudness. The quality of sound is determined by the frequencies present in it and their relative loudness.

Explain how sound produced by a vibrating object reaches your ears. What happens after it enters the ears?

A vibrating object causes air molecules to vibrate. When these vibrations reach our ears, they are collected by the pinnae and funnelled into the ear tube. These vibrations strike the eardrum, which starts to vibrate at the same frequency. This causes the delicate bones of the middle ear to vibrate. This stimulates tiny hair in the hearing organ that sends a signal to the auditory nerve of our nervous system. The auditory nerve takes the signal to the brain and we can hear the sound.

Describe an experiment to show that sound can travel through liquids.

Hold a bell in one hand and dip it in water. Now bend till your ear touches the surface of water (caution: water should not enter the ear). On ringing the bell you will hear a clear sound. This shows that sound can travel in liquids.

Describe an experiment to show that sound cannot travel through vacuum.

Take a container with a tightly held lid. Make a hole at the bottom of the container. Now, connect a vacuum pump to this hole with a rubber tube. Make sure that there is no gap between hole and tube. The vacuum pump is used to extract air from the container. Put a cell phone inside the container and close it with the lid. Now call the number of the cell phone so that it rings. We can hear the sound clearly. Extract the air from the container by switching on the vacuum pump. Again, call the number of the cell phone. This time no sound is heard because there is no air (medium) to help the propagation of sound. This experiment shows that sound cannot travel through vacuum.

An explosion occurs on moon. Will it be (a) seen (b) heard on earth instantly or after some time?

(a) It will be seen instantly on earth, as light travels at a great speed of 300000000 m/s. (b) It will not be heard on earth, as sound needs a medium to travel and there is no medium between the moon and earth.

In a game of hide-and-seek, how can the blindfolded person guess which player is closest to him?

In a game of hide-and-seek, the blindfolded person guesses the player closest to him by following the sound generated by the movement and speech of the closest player.

Page No 181:

Maninder and his friends are having a party with loud music. Sheila who lives in the neighbourhood has an exam the next day and is getting disturbed by the music. She requests Maninder to tone down the music but he refuses. Do you think this is correct? ​Mention some considerations you show towards your neighbours.

This is totally not correct. Having party, having fun is okay but too loud music is annoying as well as dangerous for us. This does not only disturbs the neighbors but it harms our ears too. In my daily life, I always keep the sound at an optimum level, when I organize a party at my house. I never disturb my neighbors by too loud music.

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• Important Questions for CBSE Class 8 Science Chapter 13 - Sound

CBSE Class 8 Science Chapter-13 Important Questions - Free PDF Download

The CBSE important questions of Chapter Sound Class 8 have been set, keeping in mind the board’s syllabus and question pattern. Professionals set Class 8 Science Sound important questions after thorough and careful evaluation of the chapter. There are MCQ-type questions along with concise type, short type, and long type. NCERT Class 8 Science Chapter 13 essential questions are also included here making sure that our students get the best possible preparation before examinations.

The crucial questions of chapter Sound Class 8 help the students clearly understand the lesson, focus on the important questions, gather knowledge, and boost their confidence before appearing in the final examinations. Vedantu is a platform that provides free CBSE Solutions (NCERT). You can also download Class 8 Maths NCERT Solutions and Class 8 Science NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations.

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Study Important Questions for Class 8 Science Chapter 13 – Sound

Very Short Answer Questions:

1. Which one the following acts as a medium for propagation of sound.

B. Gas 

C. Liquid 

D. All of These

Ans: D. All of these act as a medium for propagation of sound.

2. The range of audible sound for a human being is ____________. 

A. 20 Hz to 20,000 Hz 

B. 20 Hz to 10,000 Hz 

C. 10 Hz to 10,000 Hz

D. 20 Hz to 40,000 Hz

Ans: A. 20 Hz to 20,000 Hz is the range of audible sound for a human being.

3. The loudness of sound depends upon ______________. 

A. Amplitude 

B. Frequency

C. Time Period

Ans :A. amplitude is the property on which loudness of the sound depends upon.

4. Which one of the following will have long vocal cords? 

A. Women 

C. Children 

D. None of the above

Ans: B. Men have long vocal cords

5. Shrillness of a sound is determined by___________________ of vibration.

B. Frequency 

C. Time Period 

Ans : B. Frequency of vibration determines the shrillness of a sound.

6. Which one of the following instruments produces sound through vibrations? 

A. Ghatam 

C. Flute 

Ans: D. Sitar is the instrument which produces sound through vibration.

7. To and fro motion of an object is called _____________. 

Ans : Vibration is the to and fro motion of an object.

8. Define frequency? 

Ans : Frequency is the number of oscillations made per second. 

9. What is the unit of frequency? 

Ans: Hertz is a unit of measurement for frequency. The sign for it is Hz.

10. _______ and _______ are two important properties of any sound. 

Ans: Amplitude and frequency are two important properties of any sound.

11. In humans, sound is produced by the ______________. 

Ans : in humans, sound is produced by the Voice box or larynx 

12. For the human ear, the range of audible frequencies is roughly from ______ to ______ Hz. 

Ans: 20 to 20,000 is the range of audible sound for the human ear.

13 Define noise. 

Ans : Noise is the name given to unpleasant sounds.

14. Give two examples of noise pollution.

Ans: During an event, the use of crackers and loudspeakers .

15. What would be the sound produced in a bus station or railway station called as? 

Ans: Unpleasant noise will be produced in both locations, which is known as noise.

16. Sound cannot travel through a _____________. 

Ans : Sound cannot travel through a vacuum.

Short Answers Questions:

17. Briefly describe the loudness of sound. 

Ans: The Square of the amplitude of the vibration producing the sound determines the loudness of the sound. For example, doubling the amplitude increases the loudness by a factor of four. The decibel is a measurement of how loud something is (dB).

18. Classify the following into music and noise. Desert coolers, sound produced by harmonium, string of sitar, television and transistor radio at high volumes

19.  Describe oscillatory motion. 

Ans: Oscillating is the process of swinging back and forth in a continuous motion, and oscillating motion is the result of that process.

20.  Label the parts of the human ear in the below given picture.

Ans : A. Inner ear, B. Eardrum

21.  Correct the following statements. 

a. Noise is one which is pleasing to the ear. 

Ans : Musical sound is one which is pleasing to the ear

22. Sounds of frequencies more than 20 Hz but less than 20,000 Hz cannot be detected by the human ear. 

Ans: Sounds of frequencies more than 20 Hz but less than 20,000 Hz can be detected by the human ear.

23.  Explain with an activity that sound travels in liquids. 

Ans: Fill a bucket with water and, using one hand, shake a bell under the water, making sure the bell does not touch the bucket's body. Now carefully place your ear on the water's surface; you will hear the ringing bell, proving that sound can travel through water .

24. Give an example to show that the frequency determines the shrillness or pitch of a sound. 

Ans : A low-frequency vibration is produced by a drum. As a result, it makes a low-pitched sound. A whistle, on the other hand, has a high frequency and hence generates a higher pitch sound.

25. It is said that “The loudness of sound depends on its amplitude”. What happens to the sound when the amplitude of vibration is large and vice versa?

Ans : Because the loudness of sound is determined by its amplitude, so  the sound produced is loud when the amplitude of vibration is significant. The sound generated is weak when the amplitude is tiny.

26. Sound plays an important role in our life. Why? 

Ans : Sound is crucial because it enables us to communicate with one another.

27. Identify the type of frequency in the below given pictures.

 a. High frequency  

 b. low Frequency

Long Answers Questions:

28. Explain how sound is produced in human beings. 

Ans: The voice box or the larynx in humans produces the sound. The larynx is located near the top of the windpipe. Two vocal cords are stretched across the voice box or larynx in such a way that a thin slit for air passage is left between them. The vocal cords vibrate when the lungs force air through the slit, producing sound. The muscles that link to the voice cords can tighten or loosen them. The sort or quality of voice produced when the vocal cords are tight and thin differs from that produced when they are loose and thick.

29. Demonstrate an activity to show that sound needs a medium for propagation 

Ans: Take a tumbler, either metal or glass. Make sure it's completely dry. Put a cell phone in there. Request that a friend call this cell phone from another cell phone. Pay close attention to the ring. Now, wrap your hands over the tumbler's rim. Place your mouth in the space created by your hands. Tell your friend to ring the phone once more. While sucking air from the tumbler, listen to the ring. Keep an eye on the tumbler and take it out of your mouth. It's probable that the decreased volume of air in the tumbler contributed to the ring's decreased volume. There would be no sound if the tumbler is completely devoid of air. This demonstrates that sound requires a medium in order to travel.

30. List the harmful effect of Noise pollution

Ans : Excessive noise in the environment can lead to a variety of health issues. 

a. Lack of sleep, 

b. Hypertension (high blood pressure), 

c. Anxiety, 

d. A person who is continuously exposed to a loud sound may suffer from temporary or permanent hearing loss.

31. How can we control Noise pollution?

Ans : We must control the causes of noise pollution in order to reduce noise pollution. 

a. Aircraft engines, transport vehicles, industrial machines, and household appliances must all have noise-cancelling devices fitted. 

b. All loud operations must take place outside of any residential areas. Industries that produce noise should be located distant from such regions.

c. Automobile horns should be used sparingly. Low-volume television and music systems are recommended.

d. Trees should be planted along highways and around buildings to reduce the amount of noise that reaches households, hence lowering the negative impacts of noise pollution.

CBSE Important Questions Class 8 Science Chapter 13

Solved questions from sound chapter class 8 questions.

1. Explain how sound is produced in human beings.

Answer: The voice box or the larynx produces the sound in human beings. The larynx is at the upper end of the windpipe. A narrow slit is left between the two vocal cords because they are stretched over the larynx. This helps in the passage of air. The lungs force air through the slit, producing sound as the voice box vibrates. Muscles that are attached to the vocal cords make the cords tight or loose. When the vocal cords are flexible and thick, the type or quality of voice is different from that of when they are tight and thin.

2. Explain an activity to show that sound needs a medium to propagate.

Answer: Take a metal or glass tumbler, making sure that it is dry. Place a cell phone in it and ask a friend to ring that phone with another cell phone. Now carefully listen to the ring. Now surround the rim of the tumbler with your hands. After this, put your mouth on the opening between your hands. Now ask your friend to call the cell phone again. Listen to the ring while sucking air from the tumbler. Observe and remove the tumbler from your mouth. It is possible that the decreasing amount of air in the tumbler had something to do with the decreasing loudness of the ring. If the air is sucked completely from the tumbler, you will not hear any sound. This is how we can prove that sound needs a medium to propagate.

3. How can we control noise pollution?

Answer: We can control noise pollution by controlling the sources of noise. Following are some of the ways we can control noise pollution:

1. Silencing devices should be used in aircraft engines, industrial machines, transport vehicles, and home appliances.

2. All noisy activities should be conducted far away from residential areas. Industries should be set up away from residential areas because of how much noise they produce.

3. The use of TV, music systems, and automobile horns should be minimised. 

4. More trees should be planted to curb the harmful effects of noise pollution.

4. Describe the oscillatory motion.

Answer: Oscillation is the process of swinging to and fro in an uninterrupted manner and oscillation motion is the movement created by this process.

5. What are some of the harmful effects of noise pollution?

Answer: Excessive noise leads to many health problems in humans. Some of them    are:

Lack of sleep

Hypertension, i.e. high blood pressure

If a person is exposed to excessive noise for an extended period of time, they might temporarily or permanently face hearing loss.

Why are Important Questions for Class 8 Science Chapter 13 - Sound Necessary?

Vedantu’s Important Questions for Class  8 Science Chapter 13 - “Sound” are the finest material to understand and practice the topics in the best way.

The material carries all the information in detail and pointwise.

All the cases of the material are solved in the simplest way which explains the term clearly.

Vedantu’s Important Questions for Class  8 Science Chapter 13 - Sound provides all the main topics so that the student can focus on it and prepare for the exam. 

V encourage all Class 8 students to take advantage of the resources offered by Vedantu to learn and excel in Chapter 13 - Sound. By using the resources provided by Vedantu, students can gain a strong understanding of the concepts covered in the chapter and improve their chances of success in Science and other subjects.

In addition to the resources mentioned above, Vedantu also offers personalized online tuition classes, live interactive learning, and doubt-solving sessions. These resources can be especially helpful for students who are struggling with particular concepts or who need extra help preparing for their exams.

FAQs on Important Questions for CBSE Class 8 Science Chapter 13 - Sound

1. Will the Sound Chapter Class 8 Questions Help me?

Class 8 Science ch 13 important questions are currently available on our website in PDF format with solution keys. These important questions of chapter sound Class 8 have been compiled by our professionals keeping in mind the question pattern as given by CBSE and the questions appearing in previous years. The questions compiled are that they would help students better prepare for the upcoming examinations, grow their knowledge, strengthen their base, and boost their confidence. NCERT Chapter 8 Science essential questions are also included here to ensure students get the best preparation possible before their examinations.

2. What are Some of the Class 8 Chapter 13 Important Questions?

The Class 8 Chapter 13 crucial questions are now available on our website with a detailed analysis of the questions and a solution key. Chapter 13, Sound, is a very vital chapter that appears every year in examinations. We have compiled some MCQs, very short questions, short questions, and long questions to aid the students. This helps the students strengthen their knowledge about the Sound chapter. Some of the most common questions we see appearing each year are:

Define frequency. What is the unit of frequency?

Describe the loudness of sound.

Describe oscillatory motion.

Explain how sound is produced in human beings.

What are the harmful effects of sound pollution?

How can we control noise pollution?

3. What is an oscillatory motion?

Periodic or oscillatory motion is defined as a motion that repeats itself. Due to a regulating force or torque, an item in such motion oscillates around an equilibrium position. Regardless of whatever way the body is pushed, such force or torque tends to restore (return) the system to its equilibrium position. Two conditions must exist for vibration to take place and they are toughness and momentum. The complete explanation along with important questions of Class 8 Science Chapter 13 is easily available on Vedantu app and website.

4. Explain larynx function.

The larynx, or voice box, produces sound in humans. The larynx is located near the top of the windpipe. Because the vocal cords are stretched over the larynx, a tiny slit is left between them. The larynx moves when we swallow something.Two vocal cords can be found in the larynx. Between them, there is a little space through which the air travels. When we talk, our lungs drive air into the gap, which causes the vocal cord to vibrate, producing sound.

5. What is noise pollution?

Any unpleasant or undesired noise that interacts with or affects humans or wildlife is referred to as noise pollution. Noise pollution, despite the fact that it is always there, receives less attention than water and air quality concerns since it cannot be seen, tasted, or smelled. It is the presence of loud, unwelcome, and irritating sounds in our surroundings. By blowing their horns and making noise with their engines, motor vehicles on the road pollute the environment. For revision notes and NCERT solutions for Chapter 13 Class 8 Science, visit Vedantu.

6. How is noise pollution caused?

Outside noise is mostly generated by machines, transportation, and propagation systems all around the world. Poor urban design can lead to noise disintegration or pollution. For example, sound pollution in residential neighbourhoods can be caused by industrial and residential buildings being built next to one other. Loud music, transportation (traffic, rail, aircraft, etc. ), lawn care maintenance, building, electrical generators, explosions, and people are some of the most common sources of noise in residential neighbourhoods.

7. What is the difference between music and noise?

Noise is made up of noises with frequencies that vary in value from as low as you can hear to as high as you can hear. But not always in equal strength. The term "musical sound" refers to a sound that is agreeable to the ear. A harmonium's sound is pleasing to the ear. A sitar's string produces a musical sound as well. However, if a melodic sound grows too loud, it ceases to be melodious. To know more, solve the important questions by visiting the page Important questions for Class 8 Science and  download a free PDF of the same.

Chapterwise Important Questions for CBSE Class 8 Science

Cbse study materials.

Sound Class 8 Science Extra Questions and Answers

Sound Class 8 Science Chapter 13 Extra Questions and Answers are provided here. We prepared these extra questions based on the latest NCERT Class 8 Science Book. CBSE Class 8 Science Chapter 13 Sound Extra Questions will help you to properly understand a particular concept of the chapter.

Class 8 Science Chapter 13 Sound Extra Questions

Very short answer type question.

Question 1: Name one animal which can hear ultrasonic sounds.

Answer: Dogs

Question 2: How is sound produced?

Answer: Sound is produced by vibrating objects.

Question 3: How does an object produce sound?

Answer: Sound is produced when an objects vibrates.

Question 4: Name the sound producing organ in humans.

Answer: Voice box (larynx)

Question 5: Name the organs of hearing in our body.

Answer: Our ears are the organs of hearing in our body.

Question 6: Name that part of ear which vibrates when outside sound falls on it.

Answer: Eardrum vibrates when outside sound falls on it.

Question 7: Name the unit used to measure the loudness of sound.

Answer: The loudness is expressed in a unit called decibel (dB).

Question 8: Name the quantity whose unit is ‘hertz’.

Answer: The unit of frequency is called “hertz”.

Question 9: Does any part of the body vibrate when we speak? Name the part.

Answer: Yes, vocal chords vibrate when we speak.

Question 10: On what factor does the pitch of a sound depend?

Answer: The frequency determines the shrillness or pitch of a sound.

Question 11: What is the name of passage in outer ear which carries sound waves to the eardrum?

Answer: The sound is carried through the Ear canal.

Question 12: What is frequency of oscillation?

Answer: The number of oscillations per second is called the frequency of oscillation.

Question 13: What is the audible range of frequencies for human ears?

Answer: For human ear, the range of audible frequencies is roughly from 20 to 20,000 Hz.

Question 14: What is vibration?

Answer: The to and fro or back and forth motion of an object is termed as vibration.

Question 15: How does a sound producing object differ from silent?

Answer: A sound producing object vibrates while a silent does not. We can feel the vibrations by touching them.

Question 16: What brings the sound of a ringing telephone bell to our ears?

Answer: The sound of a ringing telephone bell travel to our ears through the air in the room.

Question 17: What is the length of the vocal cord in men and women?

Answer: The vocal cords in men are about 20mm long. In women these are about 5mm shorter.

Question 18: What does the working of a toy telephone tell us about sound?

Answer: The working of a toy telephone tells us that sound travels through solid substances.

Question 19: Who produces sound of higher pitch: a man or a woman? Why?

Answer: Usually the voice of a woman has a higher frequency and therefore, produces a sound of higher pitch. 

Question 20: Name three characteristics which are used to describe oscillations.

Answer: Frequency, amplitude and frequency are the three characteristics which are used to describe oscillations.

Question 21: What is musical sound? Give example.

Answer: Musical sound is one which is pleasing to the ear. Sound produced by a harmonium is a musical sound.

Question 22: What is noise pollution?

Answer: Presence of excessive or unwanted sounds in the environment is called noise pollution.

Question 23: What is amplitude of oscillation?

Answer: The maximum displacement of a vibrating object from its central position is called the amplitude of oscillation.

Question 24: Why can ultrasound not be heard by humans?

Answer: Ultrasound cannot be heard by humans because the ultrasound equipment works at frequencies higher than 20,000 Hz.

Question 25: What is the relation between ‘time-period’ and ‘frequency’ of an oscillating body?

Answer: Time Period given by the inverse of the frequency. Time Period = 1/frequency

Question 26: Name one solid, one liquid and one gas through which sound can travel.

Answer: Solid: Metal (Iron, Steel, Aluminium), wood, bricks etc. Liquid: Water Gas: Air

Short Answer Type Questions

Question 1: Why a sound cannot be heard on the moon?

Answer: A sound cannot be heard on the moon because on the moon there is no medium such as air though which the vibrations can propagate.

Question 2: Why should we not put a sharp, pointed or hard thing into our ears?

Answer: We must never put a sharp, pointed or hard thing into our ear. It can damage the eardrum. The damaged eardrum can impair hearing.

Question 3: How is sound produced in mridangam?

Answer: When we strike the membrane of a mridangam, the sound that we hear is not only that of the membrane but of the whole body of the instrument.

Question 4: What differences will you hear in a sound if there is an increase in (i) amplitude, and (ii) frequency?

Answer: (i) The sound will become loud on increasing the amplitude. (ii) The sound will become shrill on increasing the frequency.

Question 5: A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.

Answer: Frequency = (Number of Oscillations)/Time = 40/4 = 10 Hz

Time period = 1/(Frequency of Oscillation) = 1/10 = 0.1 sec

Question 6: Lightning and thunder take place in the sky at the same time and at the same distance from us. Lightning is seen earlier and thunder is heard later. Can you explain?

Answer: Speed of the light is more than the speed of sound. Thus, Lightning is seen earlier and thunder is heard later.

Question 7: Whose voice is more shriller: a baby or a woman?

Answer: The voice of a baby has a higher frequency (or higher pitch) than that of a woman due to which the voice of a baby is even more shrill than that of a woman.

Question 8: How does sound of a bird differ from roar of a lion?

Answer: A bird makes a high-pitched sound whereas a lion makes a low-pitched roar. However, the roar of a lion is very loud while the sound of the bird is quite feeble.

Question 9: Which produces sound of a higher pitch: a drum or a whistle? Why?

Answer: A drum vibrates with a low frequency. Therefore, it produces a low-pitched sound. On the other hand, a whistle has a high frequency and therefore, produces a sound of higher pitch.

Question 10: What frequency can dogs hear but not humans?

Answer: Some animals can hear sounds of frequencies higher than 20,000 Hz. Dogs have this ability. The police use high frequency whistles which dogs can hear but humans cannot.

Question 11: Can sound travel through a vacuum? Why or why not?

Answer: Sound cannot travel through a vacuum. A vacuum is an area without any air, like space. So, sound cannot travel through space because there is no matter for the vibrations to work in.

Question 12: How does loudness depend on the amplitude of vibrations?

Answer: Loudness of sound is proportional to the square of the amplitude of the vibration producing the sound. For example, if the amplitude becomes twice, the loudness increases by a factor of 4.

Question 13: How is sound produced in Sitar?

Answer: When we pluck the string of an instrument, like the sitar, the sound that we hear is not only that of the string. The whole instrument is forced to vibrate, and it is the sound of the vibration of the instrument that we hear.

Question 14: Why are the voices of men, women and children different?

Answer: The vocal cords in men are about 20mm long. In women these are about 5mm shorter. Children have very short vocal cords. This is the reason why the voices of men, women and children are different.

Question 15: How can you show that a sounding tabla is vibrating?

Answer: If we put some grains on the membrane of sound producing tabla, the grains will start jumping up and down showing that the tabla membrane is vibrating while producing sound.

Question 16: How can we distinguish between a man’s voice and a woman’s voice even without seeing them?

Answer: We can distinguish between a man’s voice and a woman voice even without seeing them. This is because the voice of a woman has a higher frequency and is shriller than that of a man.

Question 17: What can be done along the roads to reduce noise pollution caused by traffic from reaching the residents of the area?

Answer: Trees must be planted along the roads and around buildings to cut down on the sounds reaching the residents, thus reducing the harmful effects of noise pollution.

Question 18: State one observation from everyday life which shows that sound travels slower than light.

Answer: Lightning and thunder take place in the sky at the same time and at the same distance from us. Lightning is seen earlier and thunder is heard later. This shows that sound travels slower than light.

Question 19: What are called inaudible sounds?

Answer: The fact is that sounds of frequencies less than about 20 vibrations per second (20 Hz) and higher than about 20,000 vibrations per second (20000 Hz) cannot be detected by the human ear. Such sounds are called inaudible sounds.

Question 20: How is pitch related to frequency?

Answer: The frequency determines the shrillness or pitch of a sound. If the frequency of vibration is higher we say that the sound is shrill and has a higher pitch. If the frequency of vibration is lower, we say that the sound has a lower pitch.

Question 21: The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?

Answer: Time period = 1/(Frequency of Oscillation) Frequency of oscillations = 500 Hz Time period = 1/500 = .002 s

Question 22: What is the frequency of a vibrating body whose time-period is 0.05 second?

Answer: Time period = 1/(Frequency of Oscillation)

Or, Frequency = 1/ Time period = 1/0.05 second = 20 Hz

Question 23: By how much will the loudness of a sound change when the amplitude of vibrations is: (a) doubled? (b) halved?

Answer: (a) If the amplitude of vibrations is doubled, then the loudness will become four times.

(b) If the amplitude of vibrations is halved, then the loudness will become one-fourth.

Question 24: Write the loudness of the following in decibels: Normal breathing, Soft whisper (at 5m), Normal conversation, Busy traffic and Average factory

Answer: Normal breathing – 10 dB Soft whisper (at 5m) – 30 dB Normal conversation – 60 dB Busy traffic – 70 dB Average factory – 80 dB

Question 25: Identify the part which vibrates to produce sound in the following instruments: (a) Dholak (b) Sitar (c) Flute (d) Cymbals (e) Veena (f) Tabla

Answer: Dholak – stretched membrane Sitar – strings Flute – air columns Cymbals – metal plates Veena – strings Tabla – stretched membrane

Long Answer Type Questions

Question 1: Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.

Answer: I would suggest my parents to buy the house which is three lanes away from the roadside because being away from the road will reduce noise pollution caused by heavy traffic on the road. The intensity of noise decreases with the distance between the source and the listener.

Question 2: Explain in what way noise pollution is harmful to humans.

Answer: Presence of excessive noise in the surroundings may cause many health related problems. Lack of sleep, hypertension (high blood pressure), anxiety and many more health disorders may be caused by noise pollution. A person who is exposed to a loud sound continuously may get temporary or even permanent impairment of hearing.

Question 3: What is the frequency of the sound produced when the vocal cords are: (a) tight and thin? (b) loose and thick?

Answer: Muscles attached to the vocal cords can make the cords tight or loose.

(a) When the vocal cords are tight and thin, a sound of high frequency (high pitch sound) is produced.

(b) The frequency produced by tight and thin, a sound of low frequency (low pitch sound) is produced.

Question 4: How do we hear?

Answer: The shape of the outer part of the ear is like a funnel. When sound enters in it, it travels down a canal at the end of which a thin membrane is stretched tightly. It is called the eardrum. The eardrum is like a stretched rubber sheet. Sound vibrations make the eardrum vibrate. The eardrum sends vibrations to the inner ear. From there, the signal goes to the brain. That is how we hear.

Question 5: List sources of noise pollution in your surroundings.

Answer: Some sources of noise pollution are as follows:

• Running of mixer and grinder
• Blowing of horns of motor vehicles
• Bursting of crackers
• Taking off and landing of aeroplanes
• Sounds of loudspeakers
• High volumes in televisions and transistors

Question 6: What is the difference between noise and music? Can music become noise sometimes?

Answer: Noise: The unpleasant sounds around us are called noise.

• Blowing of horns of vehicles

Music: The sounds which are pleasant to hear are called music.

Example: Sounds from musical instruments such as harmonium, sitar, guitar, flute etc. If a musical sound becomes too loud, it would become noise.

Question 7: Sketch larynx and explain its function in your own words. Or Describe how sound is produced by the human voice box (or larynx).

Answer: In humans, the sound is produced by the voice box or the larynx. It is 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 8: State the various measures which can be taken to control noise pollution in our surroundings.

Answer: Measures to limit noise pollution

• Silencing devices must be installed in air craft engines, transport vehicles, industrial machines and home appliances.
• Use of automobile horns should be minimised.
• The noisy operations must be conducted away from any residential area.
• Noise producing industries should be set up away from such areas.
• TV and music systems should be run at low volumes.

Question 9: How can you show that sound cannot travel through a vacuum?

Answer: Take a metal glass tumbler. Place a cell phone in it. Ask your friend to give a ring on this cell phone from another cell phone. Listen to the ring carefully. Now, surround the rim of the tumbler with your hands. Put your mouth on the opening between your hands. Indicate to your friend to give a ring again. Listen to the ring while sucking air from the tumbler. You will observe that the sound become fainter as you suck. If you had been able to suck all the air in the tumbler, the sound would stop completely. Actually, sound needs a medium to travel. When air has been removed completely from a vessel, it is said that there is vacuum in the vessel. The sound cannot travel through vacuum.

At Study Path, you can also learn more about Class 8 Science Chapter 13 Sound by accessing the free exhaustive list of study materials and resources related to the chapter such as NCERT Solutions, Notes, Important Questions, and MCQ.

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Sound Assignment Worksheet for Class 8 PDF with Answers

In Class 8 Science there is a chapter “Sound Assignment”, it is a crucial lesson for the students as they get to know all the basic topics of Sound Assignment. Since it is an important lesson, students should take Sound Assignment Worksheet Class 8 to better develop an understanding of the concepts explained.

It is very important for Class 8 students to practise questions of the chapter Sound Assignment because it will help them create their own exam strategy to score well in the upcoming final examination. 

In addition to that, Sound Assignment Worksheet Class 8 has quite interactive and creative tasks which boosts student’s creativity level.

Sound Assignment Worksheet With Solutions

The questions in the chapter Sound Assignment worksheet for Class 8 are provided with solutions. Through these solutions, students can easily solve all their doubts. By clearing the doubts of Sound Assignment, students can build a strong foundation. Accordingly students can also score good marks in questions related to the chapter Sound Assignment. The subject matter experts at Selfstudys has prepared Sound Assignment Worksheet With Solutions in a way that helps students answer all types of questions regardless of its difficulty.

Sound Assignment Worksheet Class 8 PDF

Class 8 students can easily download the Portable Document Format (PDF) of Sound Assignment worksheet with the help of Selfstudys website. This can help Class 8 students to understand all the topics and concepts of the chapter Sound Assignment which will help students increase their self-confidence level. A perfect level of self- confidence can easily decrease students' level of stress to prepare for the chapter Sound Assignment.

How to Download Sound Assignment Worksheet Class 8?

To look through the questions included in Sound Assignment worksheet Class 8, students can follow the given steps. These steps are the easiest one that one can follow to download Sound Assignment Worksheet Class 8. 

• Open the Selfstudys website. 
• Bring the arrow towards the CBSE which can be seen in the navigation bar. 
• A drop down menu will appear, select KVS NCERT CBSE Worksheet.

• A new page will appear, Class 8 from the list of classes.

• Click Science from the list of subjects.

• Again a new page will appear, now select Sound Assignment Worksheet from the list of chapters. 

Features of Sound Assignment Worksheet Class 8

Before solving questions from Sound Assignment worksheet Class 8, students should understand what makes Sound Assignment Worksheet Class 8 PDF special. Features of the worksheet are discussed below: 

• All Concepts are Covered: In Sound Assignment worksheet Class 8, all concepts and topics are covered in an elaborate manner in the questions format. Through this elaboration, students can understand all the topics of the chapter Earth in a better way.  
• Explained in an Easy Language: Answers of Sound Assignment Worksheet Class 8 is explained in an easy language which helps students easily understand the process of answering questions.  
• Varieties of Questions are Included: In the Class 8 Sound Assignment worksheet, varieties of questions are included. Through this students can solve all kinds of questions of the chapter Sound Assignment. 
• Eye Catching Format: Sound Assignment Worksheet of Class 8 is considered to be an eye catching one. This eye-catching format can attract many students to solve the questions of the chapter Sound Assignment.
• Solutions are Provided: For all the questions in the worksheet of Class 8 Sound Assignment, solutions are provided. Through the solutions, Class 8 students will be able to solve challenging questions which will help them develop a critical thinking capability.
• According to the Class 8 Syllabus: The questions in Class 8 Science Sound Assignment Worksheet are as per the Class 8 Syllabus and prescribed NCERT books. With the help of this, kids will be able to make their foundational understanding stronger.

How to Know If You're Ready for Sound Assignment Worksheet Class 8? 

First of all Class 8 students need to complete the chapter Sound Assignment from the main Science book. After covering all the topics, definitions and concepts from the chapter, students are totally ready to solve the questions from Sound Assignment Worksheet Class 8. Solving the questions from the Class 8 worksheet can help students to increase their conceptual understanding of Sound Assignment. 

What Is Sound Assignment Worksheet Class 8 and How to Use It?

Sound Assignment worksheet Class 8 is mainly given to students to practise a variety of questions. After practising questions from Sound Assignment worksheet, students can also look through the answers. Answers for all questions can help students to improve their practising skills. These skills can help Class 8 students to increase their level of understanding. 

Parents are advised to tell their Class 8rd kids to begin solving Sound Assignment Worksheet Class 8 the moment they finish their study of the chapter. Doing this, will help students brush up their all learning as well as be completed for upcoming annual exams or tests.

Advantages of Sound Assignment Worksheet Class 8

Solving questions from Sound Assignment worksheet Class 8, students can be benefited a lot. Those important advantages are: 

• Boosts Confidence Level: To solve questions from the Class 8 Sound Assignment worksheet can help students to boost their confidence. A perfect level of confidence can help students to improve the study process. 
• Assist the Preparation Process: Solving questions from the Class 8 Sound Assignment worksheet can help students in preparing for the chapter. 
• Helps in Self Evaluation: Through Sound Assignment worksheet, students can easily evaluate themselves. According to the self evaluation process, students can easily improve their preparation. 
• Builds a Strong Foundation: It is important for all students to solve questions from the chapter Sound Assignment. Regular solving questions from the worksheet can help students to build a strong foundation for the chapter Sound Assignment.  
• Enhances the Learning Process: Constant solving of questions from Sound Assignment Worksheet can enhance a student's learning process so that students can understand all topics easily.  
• Quick Revision: By solving questions from the Class 8 Sound Assignment worksheet, students can easily revise all the topics and concepts included in the chapter. 

Why Sound Assignment Worksheet Class 8 Is Right for You?

It is a must for students to exercise questions from Sound Assignment worksheet Class 8 as perfectly right for them. With the help of Sound Assignment worksheet Class 8 questions, students can increase their capability of solving questions in a different and creative manner.

Tips to Understand All Questions of Sound Assignment Worksheet Class 8 in a Better Way: 

Students should understand all questions of Sound Assignment worksheet Class 8 in a better way. Better understanding of questions can help students to score good marks in questions which are related to the chapter Sound Assignment. Those important tips are: 

• Finish Off The Chapter: First and foremost tip is to finish off the chapter Sound Assignment. Students need to complete each and every topic included in the lesson. 
• Practise Questions: After completing the chapter Sound Assignment, students need to practise questions from the Class 8 worksheet. Routine practice of questions can help students in identifying their strengths and weaknesses. 
• Note Down the Mistakes: While practising questions, it is very important that students note down their mistakes. Noting down the mistakes is very important as accordingly students can improve their preparation strategies. 
•  Correction of Mistakes: After noting down the mistakes, it is a must to correct all the mistakes made. Correction of mistakes can help students to solve worksheet questions in a better way. 
• Maintain a Positive Attitude: While solving questions from the Class 8 Sound Assignment worksheet, students need to maintain a positive attitude. A positive attitude can help students to remove stress and anxiety while preparing for the chapter Sound Assignment. 
• Remain Focused: To understand questions of Sound Assignment worksheet, students need to remain focused while preparing for it. 

Why Should Students Start Solving Sound Assignment Worksheet Class 8 From the PDF?

Sound Assignment Class 8 Worksheet is provided in the PDF so that students don’t need to search for them here and there. By solving the questions from Sound Assignment worksheet Class 8, students can understand the chapter in a fine way. Routine solving of questions from the Class 8 Science Worksheet can help students increase their comprehension skills. Comprehension skills will help in performing outstanding in the final examination. 

What are Included in Sound Assignment Worksheet Class 8?

In Sound Assignment worksheet Class 8, questions from the chapter are included. After solving questions of the chapter Sound Assignment, students can also go through the answers included in the worksheet. Answers to these questions of Sound Assignment are explained in a detailed manner. As it can also help teachers to make students understand in a better and elaborate way. Through this students can easily identify their skills and flaws for the Science chapter Sound Assignment.

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MCQ Questions for Class 8 Science Chapter 13 Sound with Answers

We have compiled the NCERT MCQ Questions for Class 8 Science Chapter 13 Sound with Answers Pdf free download covering the entire syllabus. Practice MCQ Questions for Class 8 Science with Answers on a daily basis and score well in exams. Refer to the Sound Class 8 MCQs Questions with Answers here along with a detailed explanation.

Sound Class 8 MCQs Questions with Answers

Choose the correct option.

Question 1. The voice box is also called as (a) stomach (b) heart (c) larynx (d) mouth

Answer: (c) larynx

Question 2. Sound is a kind of (a) work (b) energy (c) force (d) pressure

Answer: (b) energy

Question 3. The hearing range of human ear is (a) 20 Hz to 20,000 Hz (b) less than 20 Hz (c) more than 20,000 Hz (d) 20 Hz to 25,000 Hz

Answer: (a) 20 Hz to 20,000 Hz

Question 4. Pitch of sound is determined by its (a) frequency (b) speed (c) amplitude (d) loudness

Answer: (a) frequency

Question 5. The frequency of subsonic sound is (a) more than 20 Hz (b) 100 Hz (c) less than 20 Hz (d) more than 20,000 Hz

Answer: (c) less than 20 Hz

Question 6. Cochlea is a part of (a) hearing organ (b) sound producing organ (c) muscular organ (d) air pollution

Answer: (a) hearing organ

Question 7. 1 hertz is equal to (a) 1 vibration per minute (b) 10 vibrations per minute (c) 60 vibrations per minute (d) 600 vibrations per minute

Answer: (c) 60 vibrations per minute

Question 8. Sound cannot travel through (a) air (b) water (c) iron (d) vacuum

Answer: (d) vacuum

Question 9. The sound in the audible range is called (a) ultrasonic sound (b) sonic sound (c) subsonic sound (d) light sound

Answer: (b) sonic sound

Question 10. Speed is (a) \(\frac {Distance travelled}{Time}\) (b) \(\frac {Time}{Distance travelled}\) (c) Distance travelled × Time (d) Time + Distance travelled

Answer: (a) \(\frac {Distance travelled}{Time}\)

Question 11. A pendulum oscillates 20 times in 4 seconds. Find its time period. (a) 0.05 sec. (b) 0.001 sec. (c) 0.2 sec. (d) 0.1 sec.

Answer: (c) 0.2 sec.

Question 12. Loudness of sound is determined by (a) pitch (b) frequency (c) amplitude (d) time period

Answer: (c) amplitude

Question 13. The number of vibrations made by a vibrating body in one second is (a) frequency (b) noise (c) loudness (d) pitch

Question 14. The maximum displacement of a body from its mean position is called (a) amplitude (b) oscillation (c) periodic motion (d) frequency

Answer: (a) amplitude

Question 15. The velocity of sound at 20°C is approximately (a) 3400 m/sec. (b) 340 m/sec. (c) 430 m/sec. (d) 304 m/sec.

Answer: (b) 340 m/sec.

Question 16. Sound usually travels through which medium to reach our ears? (a) Air (b) Water (c) Wood (d) Asbestos

Answer: (a) Air

Question 17. What is the speed of sound in air? (a) 110 m/s (b) 220 m/s (c) 330 m/s (d) 440 m/s

Answer: (c) 330 m/s

Question 18. What is the length of vocal cords in men? (a) 5 mm (b) 10 mm (c) 15 mm (d) 20 mm

Answer: (d) 20 mm

Question 19. What is the length of vocal cords in women? (a) 5 mm (b) 10 mm (c) 15 mm (d) 20 mm

Answer: (c) 15 mm

Question 20. A vibrating body should oscillate minimum how many times per second to make a sound audible for humans? (a) 10 times (b) 20 times (c) 30 times (d) 40 times

Answer: (b) 20 times

Question 21. The voice box is also called as (a) pharynx (b) throat (c) larynx (d) windpipe

Question 22. Speed of sound in solids is the speed of sound in liquids. (a) same as (b) greater than (c) less than (d) both (b) and (c)

Answer: (b) greater than

Question 23. To and fro or back and forth motion of an object is termed as (a) frequency (b) amplitude (c) vibration (d) time period

Answer: (c) vibration

Question 24. The sound above ……………… is physically painful. (a) 20 dB (b) 40 dB (c) 60 dB (d) 80 dB

Answer: (d) 80 dB

Question 25. If we tighten the strings of an instrument, pitch will be (a) higher (b) lower (c) constant (d) no pitch

Answer: (a) higher

Question 26. In dholak, sound is produced due to (a) stretched membrane (b) stretched strings (c) air column (d) none of these

Answer: (a) stretched membrane

Question 27. The human ear can hear sounds having frequency in range from (a) 200 to 20,000 Hz (b) 20 to 2000 Hz (c) 200 to 2000 Hz (d) 20 to 20,000 Hz

Answer: (d) 20 to 20,000 Hz

Question 28. Sound having frequency below 20 Hz is called (a) infrasound (b) ultrasound (c) megasound (d) microsound

Answer: (a) infrasound

Fill in the Blanks

Question 1. In human beings sound is produced by ………………..

Answer: larynx

Question 2. Sound of frequency lower than 20 Hz is called the ………………..

Answer: infrasonic

Question 3. The ……………….. nerve is also present in the inner ear.

Answer: auditory

Question 4. Sounds which are unpleasant to the ear is called ………………..

Answer: noise

Question 5. Too much noise in our surroundings that causes discomfort is called ………………..

Answer: noise pollution

Question 6. The speed of sound is maximum in ………………..

Answer: solids

Question 7. Sounds of frequencies higher than 20,000 Hz are called the ……………….. sound.

Answer: ultrasonic

Question 8. ……………….. is the time taken by a vibrating body for one complete vibration.

Answer: Time period

Question 9. Above ……………….. the noise becomes physically painful.

Answer: 80 dB

Question 10. Plantation on the roadside can reduce ………………..

Question 11. The hearing range of human ears is ………………..

Answer: 20 Hz to 20,000 Hz

Question 12. The loudness of normal breathing of human is ………………..

Answer: 10 dB

Question 13. Vibration is a repeated ……………….. and ……………….. motion.

Answer: to, fro

Question 14. The loudness of sound is determined by the ……………….. of vibration.

Answer: amplitude

Question 15. The human voice box is called ………………..

Question 16. Sound absorbing materials are required in an auditorium to avoid …………………….

Question 17. The two kinds of sounds we cannot hear are ……………………. and …………………….

Answer: infrasonic and ultrasonic

Question 18. ……………………. of any kind is the principle source of production of sound.

Answer: Vibration

Question 19. …………………… is an instrument used in the laboratory to produce sound of a fixed frequency.

Answer: Tuning fork

Question 20. The vibrations of a simple pendulum are also known as …………………….

Answer: oscillations

Question 21. A soft board will ……………………. most of the sound falling on it.

Answer: absorb

True or False

Question 1. All human beings can hear sounds of frequencies upto 60,000 Hz.

Answer: False

Question 2. The sound in a sitar is produced by plucking its strings.

Answer: True

Question 3. Sound cannot travel through vacuum.

Question 4. Sound does not need a medium for its propagation.

Question 5. The loudness is expressed in a unit called decibel.

Question 6. Loud sounds have high frequencies.

Question 7. Sound travel faster in air, slower in iron.

Question 8. Light travels much faster than sound.

Question 9. Man cannot hear sound of bats.

Question 10. The time taken to complete one oscillation is called frequency.

Question 11. Shriller sound has more frequency.

Question 12. Tabla is a musical instrument.

Question 13. The sound could not travel in solid.

Question 14. The pitch of a sound depends on the frequency of the waves.

Question 15. The pitch of sound produced in a guitar can be altered by reducing the vibrating length of the wire.

Question 16. Voice box is situated at the lower end of the windpipe.

Question 17. Vocal cords are of the same length in both men and women.

Question 18. Sound does not need a medium for propagation.

Question 19. The sound of sitar is produced by plucking its strings.

Question 20. Amplitude measures the pitch of sound.

Question 21. The SI unit of frequency is Hertz.

Match the following

Hope the information shed above regarding NCERT MCQ Questions for Class 8 Science Chapter 13 Sound with Answers Pdf free download has been useful to an extent. If you have any other queries of CBSE Class 8 Science Sound MCQs Multiple Choice Questions with Answers, feel free to reach us so that we can revert back to us at the earliest possible.

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Sound of Class 8

Class 8 science notes.

The sound wave was discovered back as far as Leonardo da Vinci’s  (1452–1519) era. He discovered that sound travels in waves. He was a brilliant scientist, artist, and thinker and contributed many discoveries in the field of science. He was a man before his time who thought up inventions and ideas that came to be built far later by other engineers and scientists.

Christian Doppler later discovered that sound waves could be compressed or expanded, thereby, further expanding on da Vinci’s theory.

Sound waves have been rethought and the theory re-analyzed by many scientists throughout the years.

Sound and music are parts of our everyday sensory experience. Just as humans have eyes for the detection of light and color, so we are equipped with ears for the detection of sound.

Further Reading : 

2. Hearing Impairment

3. Human Ear

• sound wave physics
• Range of hearing
• Speed of sound in different medium
• Effect of temperature on the speed of sound
• Audible, ultrasonic and infrasonic waves
• what is Echo
• What is Noise
• Hearing impairment
• The human ear
• Solved questions
• Exercise 3 (True and False)
• Exercise 4 (Subjective)

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