NCERT Solutions for Class 8 Science, Chapter 13 - Sound

The NCERT Class 8 Science, Chapter 13 deals with Sound. This chapter deals with the concept of sound and how sound travels. In this chapter, you will learn more about the frequency of sound. You will learn how sound is produced by vibrations and oscillations per second is called the frequency; the sounds by humans and concepts like larynx, vocal cords which are responsible for producing sounds in humans. You will also learn about the need for a medium for the propagation of sounds and understand that movement of sound is possible only through the right medium and cannot travel through a vacuum. Besides, you will also learn about the parts of the ear which are responsible to hear sounds in humans; you’ll understand the pitch, shrillness of sounds, audible and inaudible sounds and learn concepts like noise pollution and measures to control noise pollution.

To know more about NCERT Solutions for Class 8, Science Chapter 13, Sound, let’s look at the topics and sub-topics of this chapter:

13.1 Sound is Produced by a Vibrating Body

13.2 Sound Produced by Humans

13.3 Sound Needs a Medium for Propagation

13.4 We Hear Sound Through Our Ears

13.5 Amplitude, Time Period and Frequency of a Vibration

13.6 Audible and Inaudible Sounds

13.7 Noise and Music

13.8 Noise Pollution

In Class 8 Science Chapter 13, you will learn-

Section 13.1 – This section deals with sound is produced by a vibrating body. In this section, you will learn about the vibration in a body produces sound and when the vibrations stop, the sound stops. This section deals with the concept of vibration which is already learnt in class 7. You will learn more about this vibration and how these vibrations give rise to sound waves.

Section 13.2 – This section deals with the sound produced by humans. In this section, you will learn more about the voice box or larynx which produces sound in the human body. You will also learn about windpipe and vocal cords; understand the parts responsible to produce sound in humans, and how these parts interact to produce different sounds.

Section 13.3 – This section states that sound needs a medium for propagation. In this section, you will learn more about how sound waves travel. You will learn that sound needs a medium to travel. It cannot travel in a vacuum. Besides, you will learn by doing simple experiments on how sound waves travel in air and vacuum stops the sound waves from travelling. In this section, you will learn more about the medium of propagation of sound waves.

Section 13.4 – This section states that we hear sound through our ears. In this section, you will learn how humans hear sounds and the body parts responsible for this function. In this section, you will also learn that eardrum is mainly responsible to hear sounds in the human body. The sound travels through a canal, where at the end there is a thin membrane called eardrum. The vibrations on the eardrum are sent to the inner ear, from there the signal goes to the brain and we hear the sound. This process happens within a fraction of second and we hear sounds simultaneously.

NCERT Class 8 Science, Chapter 13 helps you to understand the concept of Sound. In this chapter, you will learn more about the sound being produced in the human body. You will also learn that sound needs a medium for propagation and sound can travel through air, metal and wood. This chapter has simple activities which help you to understand the concepts better and helps you to understand the applicability of the concepts in real life. In this chapter, you will also learn about the amplitude, time period and frequency of vibration. You will even learn about audible and inaudible sounds; also understand how sound can cause noise pollution and learn various measures that can be taken to limit noise pollution.

Section 13.5 – This section deals with amplitude, time period and frequency of vibration. In this section, you will learn about the oscillation and the oscillation per second is called frequency. You will also learn to express the frequency in terms of hertz and understand the two main concepts like amplitude and frequency of any sound. You will also learn about the loudness and pitch of a sound. This helps one to understand the loudness and shrillness of a sound.

Section 13.6 – This section deals with audible and inaudible sounds. In this section, you will learn about sounds that are audible to human ear and sounds which are inaudible to human ears. You will learn that sounds of frequencies less than 20 vibrations per second cannot be detected by the human ear. These are called inaudible sounds. Also, sounds with frequencies higher than 20,000 vibrations per second are not acceptable to the human ear.

Section 13.7 – In this section, you will learn about unpleasant sounds that are called noise. Sounds that are pleasing to the ear can be termed as music. In this section, you will learn to distinguish between pleasant and unpleasant sounds.

Section 13.8 – In this section, you will learn about the excess of noise in the environment can cause noise pollution. You will also learn about the harmful effects of noise pollution such as it causes hypertension, anxiety and lack of sleep.  You will learn useful measures to reduce noise pollution and avoid the negative consequences arising due to noise pollution.

To know more about the NCERT solutions Class 8 Science, Chapter 13 – Sound, explore the Exercises and questions below: