How are sounds made?

Sound is a type of energy made by vibrations.

When an object, such as a guitar's string, vibrates it causes air particles around it to vibrate too. This causes the air particles next to those to vibrate, and the ones next to those and so on and so on. This is called a sound wave.

Imagine throwing a stone into a pond and watching the ripples - that is similar to how sound waves work.

When sound waves reach your ears they vibrate a part of your inner ear called your eardrum, and your brain interprets this into sounds.

Sound waves travel through gases, such as air, but they can also travel through liquids (such as water) and solids (such as metal, stone and wood).

• The three bones inside your ear: the malleus (hammer), the incus (anvil), and the stapes (stirrup), are the smallest bones in the human body.

• When sounds bounce off a surface, the vibrations are reflected and you can hear them again. This is what creates an echo.

• Sound waves travel slower than light waves. That is why you see lightning before you hear thunder during storms.

• In space there is no sound, as sound waves cannot travel through a vacuum. There are of course sounds on other planets, moons and asteroids.

• Sound travels around four times faster in water than in air. Because of this, whales and dolphins can communicate over long distances.

Sounds are made when objects vibrate the air around us and send waves of energy to our ears.

Did you know?

Mice and rats communicate with each other using ultrasound.

Ultrasonic sound makes waves that vibrate so quickly that only animals with especially sensitive hearing can pick them up.

When an object vibrates, like when a drum skin is hit with a stick, the vibrations of the object causes the air particles, which are all around us, to vibrate too.

These vibrations pass from air particle to air particle and create a sound wave that then reaches your outer ear. The outer ear catches the sound wave and channels it down to the eardrum (a thin layer of skin inside your ear).

When the vibrations reach your eardrum, they cause the eardrum to vibrate, vibrating tiny bones in our ears which create electrical signals which our brain can interpret as sound.

Air particle – Air particles are tiny particles of liquid and solids that are suspended in the air.

Echo – The repetition of a sound due to reflection off another object.

Sound waves – A sound wave is a vibration that travels through a solid, liquid or gas such as the air or water.

Ultrasound – Ultrasonic sound that makes waves which vibrate very quickly. Some animals like mice and rats can hear them and we can use them to look inside the human body.

Vibrations – When an object moves back and forth very quickly.

Investigate sound vibrations.

You will need: A cup of rice, a drum (or flat surface), a drum stick or pencil.

1. Pour the rice over the drum skin.
2. Hit the drum gently. How does the rice move?
3. Now hit the drum hard. Does the rice move in the same way?
4. Now try hitting the drum with different strengths to see how the sound vibration changes.

What did you discover?