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