NCERT Solutions for Class 8 Science Chapter 13 Sound provide simple, step-by-step explanations of important concepts like vibration, sound production, pitch, loudness, and sound waves. These solutions help students complete homework easily, understand textbook questions clearly, and revise important topics quickly for tests and exams.
NCERT Solutions for Class 8 Science Chapter 13 – Sound
NCERT Solutions for Class 8 Science Chapter 13 – Sound help students understand vibrations, sound waves, pitch, and loudness in a simple way. Step-by-step answers make homework and exam preparation easier. These solutions support quick revision and help students clearly understand important concepts related to sound.
Nikita Aggarwal22 Feb, 2026
Have you ever wondered how your voice reaches a friend across a playground, or why a guitar string makes a different noise than a drum? For many students, understanding the mechanics of acoustics can feel overwhelming. You might struggle to explain why sound cannot travel through a vacuum or how the human ear actually processes vibrations.
We provide clear, accurate sound class 8 questions and answers to help you ace your school exams and build a solid foundation in science. By breaking down the NCERT syllabus into manageable sections, we ensure you grasp the "how" and "why" behind every vibration. Let's get into the world of sound and learn about the science that keeps us all connected.
Sound Class 8: Chapter Overview
Sound starts with a simple movement: a vibration. When an object moves back and forth rapidly, it creates sound. In humans, this event happens in the voice box, also known as the larynx. Inside the larynx, two vocal cords are stretched across a narrow slit. When lungs force air through this slit, the cords vibrate, producing your voice.
The Need for a Medium
Sound is a fussy traveller, unlike light. It requires a medium, be it a solid, liquid, or gas, to move from one place to another.
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Solids: Sound travels fastest through solids because molecules are packed tightly together.
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Liquids: It travels slower than in solids but faster than in gases.
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Gases: This is how we hear most sounds around us.
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Vacuum: Sound cannot travel through a vacuum because there are no molecules to carry the vibration. This is why space is silent!
Key Concepts of Sound for Class 8 Chapter
To master the sound class 8 questions and answers NCERT, you must understand the three pillars of a sound wave. These characteristics define what we actually hear.
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Amplitude: This is the maximum displacement of a vibrating object from its central position. It determines the loudness. A larger amplitude means a louder sound.
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Frequency: The number of oscillations or vibrations per second. It is measured in Hertz (Hz). Frequency determines the pitch or shrillness.
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Time Period: The time taken by an object to complete one full oscillation.
Sound Chapter Explanation in Simple Language
Here is a summary table covering the essential elements of the curriculum to help you visualize the chapter at a glance:
|
Concept |
Key Characteristic |
Units / Range |
|
Loudness |
Determined by Amplitude |
Decibels (dB) |
|
Pitch |
Determined by Frequency |
Hertz (Hz) |
|
Audible Range |
For human ears |
20 Hz to 20,000 Hz |
|
Mediums |
Sound speed: Solids > Liquids > Gases |
Material medium required |
|
Larynx |
Human voice box |
Vibrating vocal cords |
Read More - NCERT Solutions for Class 8 Maths Chapter 10 Exponents and Powers
Sound Class 8 Questions and Answers: Complete NCERT Solutions
Below are the detailed solutions for all 13 questions found in the NCERT textbook for Chapter 13. These sound class 8 NCERT solutions are designed for quick revision.
Question 1: Choose the correct answer. Sound can travel through:
(a) gases only (b) solids only (c) liquids only (d) solids, liquids, and gases.
Answer: (d) Solids, liquids, and gases.
Question 2: Voice of which of the following is likely to have the minimum frequency?
(a) Baby girl (b) Baby boy (c) A man (d) A woman.
Answer: (c) A man. (Adult males have longer and thicker vocal cords, producing lower frequency sounds).
Question 3: In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false.
(a) Sound cannot travel in a vacuum. (T)
(b) The number of oscillations per second of a vibrating object is called its time period. (F)
(c) If the amplitude of vibration is large, the sound is feeble. (F)
(d) For human ears, the audible range is 20 Hz to 20,000 Hz. (T)
(e) The lower the frequency of vibration, the higher is the pitch. (F)
(f) Unwanted or unpleasant sound is termed as music. (F)
(g) Noise pollution may cause partial hearing impairment. (T)
Question 4: Fill in the blanks with suitable words.
(a) Time taken by an object to complete one oscillation is called time period.
(b) Loudness is determined by the amplitude of vibration.
(c) The unit of frequency is Hertz (Hz).
(d) Unwanted sound is called noise.
(e) Shrillness of a sound is determined by the frequency of vibration.
Question 5: A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
Answer: * Frequency = Total Oscillations / Total Time = 40 / 4 = 10 Hz.
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Time Period = 1 / Frequency = 1 / 10 = 0.1 seconds.
Question 6: 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: * Frequency = 500 Hz.
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Time Period = 1 / Frequency = 1 / 500 = 0.002 seconds.
Question 7: Identify the part which vibrates to produce sound in the following instruments:
(a) Dholak: Stretched membrane
(b) Sitar: Stretched strings
(c) Flute: Air column
Read More - NCERT Solutions for Class 8 Maths Chapter 1 Rational Numbers
Question 8: What is the difference between noise and music? Can music become noise sometimes?
Answer: Noise is an unpleasant, irregular sound (e.g., traffic honking), while music is a pleasant, rhythmic sound. Yes, music can become noise if it is played at extremely high volumes that become irritating or harmful.
Question 9: List sources of noise pollution in your surroundings.
Answer: Key sources include:
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Vehicle horns and traffic.
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Kitchen appliances like mixers.
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Loudspeakers and high-volume TV.
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Industrial machines and crackers.
Question 10: Explain in what way noise pollution is harmful to humans.
Answer: Noise pollution causes several health issues:
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Lack of sleep (insomnia).
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Hypertension (high blood pressure).
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Anxiety and permanent hearing impairment.
Question 11: Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away. Which house would you suggest?
Answer: I would suggest the house three lanes away. The roadside house will have high levels of noise pollution from traffic, while the house further away will be much quieter and healthier.
Question 12: Sketch the larynx and explain its function in your own words.
Answer: The larynx (voice box) is at the top of the windpipe. It has two vocal cords stretched across it with a narrow slit. When air passes through, the cords vibrate to produce sound.
Question 13: Lightning and thunder take place in the sky at the same time. Lightning is seen earlier, and thunder is heard later. Why?
Answer: This phenomenon is because the speed of light is significantly faster than the speed of sound. Light reaches us almost instantly, while sound takes longer to travel.
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NCERT Solutions for Class 8 Science Chapter 13 Sound FAQs
How do humans produce sound?
Humans produce sound through the larynx. Air from the lungs passes through the slit between the vocal cords, causing them to vibrate.
What is the unit of loudness?
The loudness of sound is expressed in decibels (dB). Sounds above 80 dB are generally considered noise.
Does sound travel through a vacuum?
No, sound cannot travel through a vacuum. It requires a material medium (solid, liquid, or gas) to propagate.
What determines the pitch of a sound?
The pitch of a sound is determined by its frequency. A higher frequency results in a higher pitch.
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