We mostly take ‘sound’ for granted, but it has magical properties. Here Superhailer’s acoustics expert Matt Henry picks out his 20 favourite facts about sound.
1. Sound is what happens when vibrations of molecules move through matter. When you clap your hands together, it causes vibrations and the particles in the air to move and bump into one another. They in turn bump into more air molecules, creating a sound wave.
2. If a human ear is within range of an audible sound wave, tiny hairs inside vibrate and allow the listener to hear what the original sound was. (The clicking of a finger, an explosion, music etc.)
3. Humans can hear sound waves that range only between 20 and 20,000 vibrations a second. Less than that is called subsonic and more than that is ultrasonic.
4. Sound needs a medium to work – like air or water.
5. There is no sound in space – because it’s a vacuum with no molecules to bump into one another (or vibrate the hairs in our ears).
6. Sound travels four times faster in water than air – because there are more molecules in water to bump into each other.
7. Whale voices in the oceans can be heard almost 500 miles away.
8. Sound travels at 1,230 km per hour – 767 miles per hour.
9. Sound is fast – but light travels millions of times faster – 670 million miles per hour. (That’s why you see a lightning flash before you hear the thunder.)
10. Sonic booms are created when an object (e.g. jet plane) travels through the air faster than the speed of sound. They generate enormous amounts of sound energy, appearing to the human ear similar to an explosion.
11. The crack of a whip is a sonic boom in miniature.
12. The Superhailer loud hailer (pictured) can project a crystal clear live spoken word, prerecorded messages and alerting sounds over extreme distances – of up to 800 ft (250m).
13. Your ears are not the only parts of your body to ‘hear’ sounds – our bodies can often feel the force of large sound waves – such as a thunder.
14. Thunder is caused when lightning causes the air around it to heat up and expand so fast that it breaks the sound barrier.
15. Wind has no sound – it’s only the noise of it hitting objects that you can hear.
16. An echo is when a sound wave bounces off an object instead of being absorbed by it.
17. Sound can harm or even kill. Dolphins can create directional bursts of sound in water which are loud enough to stun nearby fish, helping them hunt.
18. The Superhailer is super safe. Before it transmits any sound a clever in-built range finder instantly measures the distance to the target. This information is fed to the onboard safety limiter to determine what the safe volume level should be.
19. The loudest sound ever recorded was the eruption of Krakatoa in 1883 – it was heard 4,000 miles away.
20. Acousticophobics are scared of noise.