Sound Energy

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Welcome to class! 

In today’s class, we will be talking about sound energy. Enjoy the class!

Sound Energy

Sound is a form of energy produced when objects vibrate. It is conveyed from the vibrating body, through a medium and to the listener. Sound can be produced by both living things and non-living things, e.g. birds, metals, animals, wood, air, musical instruments, metals, thunder, rainfall, etc.

Production of sound

Sound is produced when a bod vibrates. The vibrating body then causes the medium (air, liquid and solid) around it to also vibrate. Unlike light, sound requires a material medium for its propagation.

Sound speeds in different material medium are affected by some properties, such as temperature, humidity, or the direction of the wind, of the medium in which it propagates.

Transmission of sound

Sound is transmitted through a medium such as air, water in the form of vibration or longitudinal wave. Sound cannot travel in space (vacuum) because it always requires a material medium for its propagation or transmission. The propagation of sound in the air cannot be seen whereas, it can be seen in water as waves.

Sound transmission through a medium can be demonstrated experimentally by:

1. By dropping a stone or any object inside a pool of water, there will be an outward movement called ripples/waves. This wave continues its outward movement until it hits an obstacle such as wood, riverbank, etc. This obstacle then causes the wave to be reflected in the opposite direction.
2. Making sound by facing a wall, with the help of a stopwatch, the time it will take before you hear the reflected sound after hitting the wall can be calculated. The reflected sound heard after the reflection of the sound wave from aboard plane surface is called an echo.

Hearing

The ear is a sense organ that helps to hear a sound. The ear is made up of three layers: the outer layer, middle layer and the inner layer. The outer layer consists of the visible portion of the ear, which consists of the external ear lobe and a tube through which sound energy travels. The middle layer of the ear lies between the outer layer and the inner layer. It consists of the eardrum, ossicles (three tiny bones), and the cavity.

In this layer, sound wave makes the bones in the middle ear to vibrate, amplified and transmitted to the inner ear layer. In the inner layer, the vibration is detected by nerves in the inner ear, which then translate them into signals and sends it to the brain. The brain then interprets the signal as a sound. The human ear can hear the sound of frequency as low as 20Hz and as high as 20kHz. Dogs can hear frequencies up to 25kHz.

 

In our next class, we will be talking more about Sound Energy.  We hope you enjoyed the class.

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