Sound – Short Answer Type Questions
CBSE Class 8 Science – Chapter Wise Study Materials Based on NCERT
Chapter 13: Sound – Short Answer Type Questions with Answers
Suitable for:
Annual Examination • Periodic Tests • Class Tests • Pre-Board / School Level Board Exam Pattern
These Short Answer Type Questions with Answers are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 8 board exams standard.
This page presents a comprehensive, topic-wise set of 50 Short Answer Type Questions from
Chapter 13: Sound with clear, easy-to-understand answers to support NCERT-based revision and exam preparation.
Short Answer Type Questions – Chapter 13: Sound
A. Basic Concepts of Sound and Vibrations
Q1.What is sound? Explain with a simple example.
Ans. Sound is a form of energy that produces a sensation of hearing in our ears. For example, when a bell rings, the sound energy produced by the vibrating bell reaches our ears and we hear the ringing sound.
Q2.How is sound produced in general?
Ans. Sound is produced when an object vibrates. The vibration disturbs the particles of the surrounding medium and this disturbance travels as sound waves. When these waves reach our ears, we are able to hear the sound.
Q3.What do you understand by the term vibration? Give one example.
Ans. Vibration is the to-and-fro or back-and-forth motion of an object about its mean position. For example, the prongs of a tuning fork move to and fro rapidly when it is struck, showing vibration.
Q4.Explain how a stretched rubber band can produce sound.
Ans. When a stretched rubber band is plucked, it starts vibrating. These vibrations disturb the surrounding air particles and sound waves are produced. As these sound waves reach our ears, we hear the sound of the rubber band.
Q5.What will happen to sound if the vibrations of the source gradually decrease and then stop?
Ans. As the vibrations decrease, the sound produced becomes fainter due to less energy. When the vibrations stop completely, no disturbance is produced in the medium, so the sound also stops and we cannot hear anything from that source.
Q6.How do human beings produce sound while speaking?
Ans. Human beings produce sound with the help of vocal cords present in the voice box or larynx. When air from the lungs passes through the stretched vocal cords, they start vibrating. These vibrations produce sound, which we use for speaking and singing.
Q7.Why are children’s voices generally sharper or shriller than adults’ voices?
Ans. Children have shorter and thinner vocal cords compared to adults. Short, thin cords vibrate faster and produce sound of higher frequency. A higher frequency sound has a higher pitch, so children’s voices usually sound sharper or shriller.
B. Propagation of Sound and Need for a Medium
Q8.What is meant by propagation of sound?
Ans. Propagation of sound refers to the way sound travels from the vibrating source to the listener. It involves the transfer of vibrations from one particle of the medium to the next, forming sound waves that move outward from the source in all directions.
Q9.Why can we not hear any sound on the Moon?
Ans. We cannot hear sound on the Moon because there is almost no atmosphere there. Sound needs a material medium such as air, water or solids to travel. In the absence of air or any other medium, sound waves cannot propagate, so no sound is heard on the Moon’s surface.
Q10.How does sound travel through air from a source to our ears?
Ans. When a source vibrates, it pushes and pulls the surrounding air particles, creating compressions and rarefactions. These regions move forward as longitudinal sound waves. When these waves reach our ears, they strike the eardrum and produce the sensation of hearing.
Q11.Give one simple activity to show that sound travels through a solid medium.
Ans. Place your ear on a wooden table while a friend gently taps the other end of the table with a spoon. You will hear the tapping sound clearly through the wood. This shows that sound can travel through a solid medium like wood.
Q12.State the three different media through which sound can travel. In which of them does sound generally travel fastest?
Ans. Sound can travel through solids, liquids and gases. It generally travels fastest in solids, slower in liquids and slowest in gases, because particles are closest in solids and can pass on vibrations more quickly.
Q13.What will happen to sound if there is no medium between the source and the listener?
Ans. If there is no medium between the source and the listener, sound cannot reach the listener. Without particles to carry vibrations, sound waves cannot travel, so no sound will be heard even if the source is vibrating strongly.
Q14.Why is sound heard earlier through a railway track than through air when a train is approaching?
Ans. Sound travels faster in solids than in air. When you place your ear on a railway track, the vibrations from the moving train reach you more quickly through the solid metal track than through the air, so you hear the sound earlier.
C. Characteristics of Sound – Amplitude, Frequency, Loudness and Pitch
Q15.Define amplitude of vibration. How does it affect the sound produced?
Ans. Amplitude is the maximum displacement of a vibrating particle from its mean position. A larger amplitude means the vibrating body has more energy and produces a louder sound, while a smaller amplitude produces a softer sound.
Q16.What is loudness of sound and on which factor does it depend?
Ans. Loudness is the measure of how strong or weak a sound appears to our ears. It mainly depends on the amplitude of vibration. Greater amplitude produces greater loudness, and smaller amplitude produces lesser loudness for the same frequency and distance.
Q17.Define frequency. What is its SI unit?
Ans. Frequency is the number of complete vibrations made by a vibrating body in one second. It tells us how fast an object is vibrating. The SI unit of frequency is hertz (Hz), where 1 hertz equals 1 vibration per second.
Q18.What do you mean by time period of vibration? How is it related to frequency?
Ans. Time period is the time taken to complete one full vibration. It is related to frequency by the relation: Time period = 1 / Frequency and Frequency = 1 / Time period. Thus, higher frequency means a smaller time period and vice versa.
Q19.Explain the term pitch of a sound with an example.
Ans. Pitch is that characteristic of sound which helps us distinguish between a shrill and a deep sound. For example, the sound produced by a whistle has a high pitch, while the sound produced by a drum has a low pitch. Pitch depends on the frequency of vibration of the sound-producing body.
Q20.How are pitch and frequency of sound related?
Ans. Pitch of a sound depends directly on its frequency. A sound with higher frequency has a higher pitch and is perceived as shrill, while a sound with lower frequency has a lower pitch and is perceived as deep or flat. Thus, pitch increases with increase in frequency.
Q21.Two sounds are produced by the same instrument, one loud and the other soft. How do their amplitudes and frequencies compare?
Ans. For the same instrument, a loud sound has a larger amplitude of vibration, while a soft sound has a smaller amplitude. However, their frequency (and therefore pitch) may remain the same, so they sound alike except for the difference in loudness.
Q22.What is meant by quality or timbre of sound?
Ans. Quality or timbre is the characteristic of sound that helps us distinguish between sounds of the same pitch and loudness produced by different instruments. For example, a note played on a flute and the same note on a violin sound different because of difference in quality or timbre of the sound.
Q23.Why does the sound of a drum differ from the sound of a flute even if both are played at the same loudness?
Ans. The sound of a drum differs from that of a flute because the way they vibrate and the waveforms they produce are different. This leads to different quality or timbre of sound. Thus, even with the same loudness, our ears can easily distinguish between the two instruments.
Q24.Explain why a thick string of a guitar produces a deeper sound than a thin string.
Ans. A thick string has more mass, so it vibrates more slowly and with a lower frequency compared to a thin string. Lower frequency produces a lower pitch or deeper sound. Hence, the thick string of a guitar gives a deep sound, while the thin string gives a sharper sound.
D. Audible Range, Musical Sound and Noise
Q25.What is the audible range of frequency for a normal human ear?
Ans. The audible range for a normal human ear is roughly from 20 hertz (Hz) to 20,000 hertz (Hz). Sounds with frequencies in this range can usually be heard by a healthy human ear, while sounds below or above this range cannot be heard.
Q26.What are infrasonic sounds? Can humans hear them?
Ans. Infrasonic sounds are those having frequency less than about 20 Hz. Humans cannot hear these low-frequency sounds because they fall below the audible range of the human ear. Some animals, however, can sense such low-frequency vibrations.
Q27.What are ultrasonic sounds? Mention one use of ultrasonic sound.
Ans. Ultrasonic sounds are sounds having frequency greater than about 20,000 Hz. Humans cannot hear them, but many devices use ultrasonic waves. One use is in medical ultrasound scanning, where ultrasonic waves help doctors to see images of organs inside the body.
Q28.Differentiate between musical sound and noise with examples.
Ans. Musical sound is pleasant to hear, has a regular pattern and is produced in a controlled way, for example, sound from a harmonium or flute. Noise is unpleasant, irregular and often loud, such as the sound of traffic jam or loud shouting in a crowded market.
Q29.Why is the sound of a school band considered music while the sound of crackers is considered noise?
Ans. A school band plays instruments in rhythm and harmony, producing a regular, pleasant sound, so it is music. Crackers produce sudden, irregular and very loud sounds which are harsh and disturbing, so they are considered noise and can also cause noise pollution.
Q30.Can the same sound be music for one person and noise for another? Explain with an example.
Ans. Yes. The same sound can be music for one person and noise for another. For example, loud rock music may be enjoyable for some teenagers, but the same music may disturb an elderly person who finds it harsh and noisy. Our liking and situation decide whether a sound is music or noise for us.
Q31.Why should we keep the volume of TV and music systems low at home?
Ans. Keeping the volume low prevents sound from turning into noise. Loud sound can disturb other family members, neighbours and may also harm our ears if heard for a long time. Low volume helps maintain a peaceful environment and protects our hearing ability.
Q32.Give two examples of situations in school where noise should be strictly avoided.
Ans. Noise should be avoided near classrooms where students are studying or writing examinations, because it disturbs concentration. It should also be avoided near the library, as students need a quiet atmosphere for reading and self-study.
E. Noise Pollution – Causes, Effects and Control
Q33.What is noise pollution? Give a simple definition.
Ans. Noise pollution is the presence of excessive, unwanted or harmful sound in the environment that causes discomfort to human beings and animals. It is mainly caused by loud and continuous noise coming from various sources around us.
Q34.List any four common sources of noise pollution in cities.
Ans. Four common sources of noise pollution in cities are: heavy traffic and continuous honking of vehicles, construction work and big machines, loudspeakers used in functions and rallies, and loud music in markets, cinema halls and parties.
Q35.Explain how noise pollution can affect students’ studies.
Ans. Noise pollution distracts students and makes it difficult to concentrate on reading or writing. Continuous loud noise may cause irritation and headache. Because of these factors, students may not understand or remember what they study, which can affect their performance in examinations.
Q36.Mention any three health problems caused by long-term exposure to loud noise.
Ans. Long-term exposure to loud noise can cause health problems such as constant headache and fatigue, lack of concentration and disturbed sleep. In extreme cases, it may also lead to partial or permanent hearing loss in people exposed to loud sounds for many years.
Q37.How do crackers contribute to noise pollution, especially during festivals?
Ans. Crackers produce sudden, very loud and sharp sounds when burst. During festivals, large numbers of crackers are used within a short time. This creates a high level of noise in the environment, disturbing children, elderly people, patients and animals, thus causing serious noise pollution.
Q38.Suggest three ways in which you as a student can help in reducing noise pollution.
Ans. As a student, you can avoid using loud crackers, keep the volume of TV, music players and mobile phones low, and request others not to use horns unnecessarily. You can also spread awareness among friends and neighbours about the harmful effects of noise pollution.
Q39.How can planting trees along roadsides help in controlling noise pollution?
Ans. Trees act as natural barriers to sound. Their leaves, branches and trunks absorb and scatter sound waves. Planting trees along roadsides and around buildings reduces the intensity of noise coming from traffic and other sources, thus helping to control noise pollution in that area.
Q40.What are “silence zones” and why are they important?
Ans. Silence zones are areas where making loud noise is restricted or banned, such as near schools, hospitals and courts. They are important because students need quiet for studying, patients need rest for recovery, and serious work is done in such places. Reduced noise in these zones protects health and improves concentration.
F. Human Ear – Structure and Working
Q41.Name the three main parts of the human ear and write their sequence from outside to inside.
Ans. The three main parts of the human ear are the outer ear, the middle ear and the inner ear. The sequence from outside to inside is: outer ear → middle ear → inner ear. All three parts work together to help us hear sound.
Q42.What is the function of the pinna and ear canal in the outer ear?
Ans. The pinna collects sound waves from the surroundings and directs them into the ear canal. The ear canal then carries these sound waves towards the eardrum. In this way, the outer ear helps in gathering and guiding sound into the ear for hearing.
Q43.What is eardrum? How does it respond when sound waves fall on it?
Ans. The eardrum, or tympanum, is a thin, tightly stretched membrane present at the end of the ear canal. When sound waves fall on it, it starts vibrating back and forth with the same frequency as that of the sound waves. These vibrations are then passed to the middle ear bones.
Q44.Name the three bones present in the middle ear. What is their main function?
Ans. The three bones in the middle ear are called hammer, anvil and stirrup. They are linked together and receive vibrations from the eardrum. Their main function is to increase or amplify these vibrations and pass them on efficiently to the inner ear (cochlea).
Q45.How are vibrations finally converted into electrical signals in the ear?
Ans. The amplified vibrations from the middle ear reach the cochlea in the inner ear. The cochlea is filled with fluid and contains sensitive nerve cells. The vibrations cause movement in the fluid, stimulating the nerve cells. These cells convert mechanical vibrations into electrical signals which are sent to the brain through the auditory nerve.
Q46.How does the brain help us in hearing sound?
Ans. The brain receives electrical signals from the cochlea through the auditory nerve. It interprets these signals as specific sounds such as speech, music or noise. Thus, even though the ear detects vibrations, it is the brain that finally recognises and makes sense of the sounds we hear.
Q47.Why is it important to protect our ears from very loud sounds?
Ans. Very loud sounds can damage delicate parts of the ear, especially the eardrum and the tiny hair cells in the inner ear. Continuous exposure to loud noise may cause ringing in the ears, partial hearing loss or even permanent deafness. Therefore, protecting our ears from loud sounds is very important for maintaining good hearing.
G. Ear Care and Everyday Applications
Q48.Write any three precautions that should be taken to protect our ears.
Ans. We should avoid listening to very loud music on earphones, stay away from extremely noisy places whenever possible, and never insert sharp objects like pins or matchsticks into the ears. These precautions help prevent injury and hearing problems.
Q49.How do headphones and earphones, when used carelessly, harm our hearing?
Ans. When headphones and earphones are used at very high volume or for a long time, a lot of sound energy directly enters the ear. This continuous loud sound can damage the eardrum and the inner ear cells, leading to hearing problems such as reduced hearing and ringing in the ears.
Q50.Why is it important to consult a doctor if we feel pain or continuous ringing in our ears?
Ans. Pain or continuous ringing in the ears may be a sign of infection, injury or damage to some part of the ear. If not treated in time, it can lead to more serious problems or permanent hearing loss. Therefore, consulting a doctor early helps in proper treatment and protects our hearing.
These 50 Short Answer Type Questions and Answers on Chapter 13: Sound strictly follow the
NCERT Class 8 Science syllabus and CBSE pattern, making them excellent for topic-wise revision,
homework support and exam preparation as per Class 8 board exams standard.