Sound comes from vibrations — Physical education, 4–6 years
See how a plucked string, a drum and your voice make the air move and create sound. Physical education, 4–6 years.
What is a vibration?
A vibration is a quick back-and-forth movement. When a string, drum skin or your voice box vibrates, it makes nearby air move. That moving air can reach your ears as sound.
Why does this matter?
People wanted to understand why a quiet-looking string could make a loud note, and why a drum stopped sounding when its skin stopped moving. Thinking about vibrations links the part you can see moving with the sound you hear.
Try a ruler
Place 10 centimetres of a plastic ruler over the edge of a table and hold the rest still. Pluck the overhanging end: it moves quickly and makes a note. Hold it so only 3 centimetres hang over, then pluck again; the shorter part vibrates faster and the note is higher.
A sound is not the thing itself
It is easy to say that a bell contains a sound, because the sound begins when the bell is hit. But the bell only vibrates and makes the air vibrate; the sound is what your ears and brain notice. When the bell stops moving, the sound fades.
Where do we use this?
Guitars, piano strings, speakers and headphones all use vibrating parts to make sound. A microphone does the reverse: sound makes a thin part vibrate, and the device changes that movement into an electrical signal. Your voice also starts with vibrating vocal folds.
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