The first day, a teacher enters into your class room. What do you say to the teacher? You all wish a very good morning to the teacher.
Suppose, If all the doors in your room are closed, then how can you guess whether anyone is crossing the room? Yes. You can identify it by hearing the footsteps of the person.
Everyday your world is filled with a multitude of sounds. Sound can let you communicate with others or let others communicate with you. It can be an enjoyable experience or a warning of danger. Some sounds can be heard by dogs or other animals but cannot be heard by humans. All this happens due to the vibrating bodies.
When a particle moves to and fro about its mean position rapidly, it is said to vibrate and this vibration is the cause for the sound. Thus every source of sound is a vibrating body.