It is produced by vibration of different objects

We are able to hear when these vibrations reach our ear

 

What is vibration?

Rapid to and fro motion of an object is called Vibration.

This motion is also known as Oscillatory Motion

 

Example 1

If we strike a pan, it vibrates and produces sound

When these vibrations reach our ear , we are able to hear sound

When pan stops vibrating, it stops producing sound

Example 2

If we pluck a rubber band, it vibrates and produces sound

When these vibrations reach our ear, we are able to hear sound

 

How does vibration produce sound?

We know that sound travel through a medium like air

When an object vibrates, it forces the particles of medium around it to also vibrate

 

They cause the neighbouring particles to vibrate and so on

This process continues until the vibrations reach the person's ear and we are able to hear sound

Note

The particles do not travel from source of sound to the ear

One particle vibrates and displaces adjoining particle and make it vibrate and process continues

 

Example

If we strike an iron bell,the bell vibrates (move in to and fro)

These vibrations cause nearby air particles to vibrate and so on

When these vibrations reach our ear, we are able to hear sound



Different examples of vibration of sound

Human Voice 

We are able to hear human voice because of vibration of vocal cords

 

Sound of Birds Wings 

When birds flap their wings,

because of vibration of wings,sound is produced

 

Sound of stretched Guitar strings

When we stretch a guitar string, it produces vibrations in the guitar

When these vibrations reach our ear, we are able to hear sound



Questions

Intext Question 1 Page 162 - How does the sound produced by a vibrating object in a medium reach your ear?

View Answer

 

Intext Question 3 Page 163 - Suppose you and your friend are on the moon. Will you be able to hear any sound produced by your friend?

View Answer

 

NCERT Question 1 - What is sound and how is it produced?

View Answer

 

 

  1. Class 8
  2. Chapter 13 Class 8 - Sound

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.