NCERT Solutions for Class 8 Science Chapter 13:Sound

In this chapter, we will study about sound and its importance in our daily lives. We will learn about how sound is produced by vibrating bodies. In particular, we will also study about how humans make sound and interact. We will read about mediums and how these mediums help in propagating sound. We will also study about human ears and how they help us in receiving sounds. The chapter would also explain concepts like amplitude and time period and the frequency of sound. The chapter will conclude by giving us a brief about noise pollution and its harmful effects.

• Sound helps us in communicating with other people.
• Back and forth motion of an object is called vibration.
• Sound propagates through vibrations.
• Various examples in the chapter illustrate vibrations observable in our daily lives.
• In human beings, certain varied features are also used to make sounds.
• Our voice box or larynx, windpipe and two vocal cords play an instrumental role in creating sounds.
• We also learn about vacuum and how sound does not travel in a vacuum
• The chapter goes on to explain the structure and functioning of our ears.
• We learn about the funnel, the eardrums and the inner ear from where vibrations travel to the brain.
• We also study the relationship between oscillations, frequency and its S.I. unit – Hertz.
• Its amplitude decides loudness or pitch of a sound.
• We also learn about audible and inaudible sounds, according to Hertz.
• The difference between musical sounds and plain noise is also illustrated in the chapter.
• We conclude the chapter by learning about noise pollution and its harmful effects.
• We are also informed of various ways to limit noise pollution.