Back to: Jss3 Basic Science

Introduction

Sound is an example of a type of energy. Sound energy is the energy that is made when sound waves move through the air, water, or any other medium. In this lesson, you will learn how sound is made, how it moves, and how it is reflected.

Meaning Of Sound

Sound is a wave that is made when things move. It is something that vibrating things have. These things could be solid, liquid, or gas. If there is an elastic medium—that is, a medium that can be compressed—between the object that is vibrating and a suitable device, like a microphone or an animal’s ear, noise or sound will be picked up.

Sound can be made in a number of ways, but it’s usually caused by mechanical disturbances that make an object vibrate.

For instance:

• When you hit a piece of iron with a hammer, both the iron and the hammer vibrate for a short time.
• When the bow rubs against a guitar string, the string vibrates.
• When you hit a drum, it makes a sound because the skin is tight and stretched out.
• When air leaves the lungs through the larynx, it makes the vocal cords of people vibrate.
• When an explosion happens, it makes the air around it shake.

Production Of Sound

When a force makes an object vibrate, it makes a sound. In a wave, the sound energy moves through the material. For instance, the sound of drums being played at a party sends energy out into the environment. The kinetic energy of the moving air then transfers the sound energy to the dancers’ eardrums.

Transmission Of Sound

This is the movement of sound from one place to another, like from one room in a building to another or from the street into a room in the building.

A tuning fork can be used in the lab to show how sound travels and how sound is made. The tuning fork has two steel prongs that make a sound when hit with something hard. During the vibration, the tuning fork’s prongs look hazy because they are moving quickly back and forth. If you put the vibrating prongs into a beaker of water, the water will be violently stirred. Resonance is the process by which the natural vibrations of the tuning fork are passed on to the water.

Sound moves through things like air, water, and even solid metals. A medium is a matter or material that allows sound to travel. Sound moves through solids faster than through liquids and through liquids faster than through gases. The speed of sound in dry air is 332 m/s, in water it is 1484 m/s, and in iron, it is 5120 m/s.

Sound Reflection

When sound hits a special curved surface called a parabola, it will bounce back in a straight line no matter where it first hits.

Many stages for entertainment are shaped like a parabola so that the sound goes straight into the crowd instead of bouncing around on the stage. If another curve surface closes off the parabola, the shape is called an ellipse. No matter where the sound hits the wall, it will move from one point to another.

An ellipse is the shape of a whispering gallery. If your friend stands at one focal point and you stand at the other, you will be able to hear his whisper clearly. No one else in the room will be able to hear anything. Echoes happen when sound waves bounce back and forth.

An echo is a sound that comes back to where it came from. Reverberation, on the other hand, is when several echoes overlap.

Hearing

Hearing is being able to recognise sounds by picking up on vibrations or changes in the pressure of the air around you. This is done through an organ called the ear. Deafness is when the ear can’t hear anything. The outer ear, the middle ear, and the inner ear are the three main parts of the ear.

The parts of the ear that you can see, the pinna, the auditory canal, and the eardrum, are all part of the outer ear. Sound moves in waves, and when these waves hit the eardrum, they make the eardrum move. The eardrum changes the air pressure waves that come into a single wave with a certain size (amplitude). This makes it possible to tell different sounds apart.

Behind the eardrum is a smaller chamber filled with air that makes up the middle ear. The chamber holds the ossicles, which are the three smallest bones in the body. The malleus (hammer), incus (anvil), and stapes are the ossicles (stirrup). The tiniest bone in the body is the stapes. The ossicles help the vibrations from the eardrum get to the inner ear and get stronger.

The cochlea is a coiled canal filled with fluid that is part of the inner ear. It is connected to nerve cells that send signals to the brain.