1. What is Sound?
Sound is a form of energy that travels as vibrations through a medium. These vibrations reach our ears and create the sensation we call hearing.
Whenever something vibrates, it disturbs the particles around it. These tiny disturbances move outward and finally reach the ear.
2. How Sound is Produced
Definition: Sound is produced when an object vibrates back and forth.
Every sound you hear—whether it's a guitar string, a speaker, or a ringing phone—starts with some part moving rapidly.
The vibrating object pushes the air particles around it. These pushed particles then push the next ones, and the disturbance keeps moving forward.
2.1. Examples of Sound Production
- When we pluck a string, it vibrates and produces sound.
- A drum skin vibrates when struck.
- The vocal cords vibrate when we speak.
3. How Sound Travels
Sound needs a medium to travel. This medium can be air, water, or a solid surface.
The vibrating object creates regions where particles are close together (compressions) and regions where they are spread out (rarefactions). These move as a wave.
3.1. Compressions and Rarefactions
Compression: Region where particles are crowded together.
Rarefaction: Region where particles are spread apart.
3.1.1. How to Visualise This
Imagine pushing a spring from one end. Some coils bunch together (compression), while others spread out (rarefaction). This is similar to how sound moves through air.
4. How We Hear Sound
When sound waves enter the ear, they make the eardrum vibrate. These vibrations pass through tiny bones and reach the inner ear, where they are converted into electrical signals. The brain interprets these signals as sound.
4.1. Step-by-Step Hearing
- Sound waves enter the ear canal.
- The eardrum vibrates.
- Vibrations pass through three tiny bones.
- The inner ear converts them into signals.
- The brain recognises the sound.
5. Everyday Examples
- Listening to music from a speaker.
- Hearing footsteps in the hallway.
- A phone vibrating on a table.