What have a dolphin and an off-key pop singer got in common?

Apart from the fact that they both need a friendly tuna (geddit?)

The answer is that they both use ECHOES to survive.

To learn more about the reverberating world of echoes click on the links below. if you’re a dolphin, just click.

		Hello…hello…hello… … to echoes…echoes…echoes
		Living in the material world bricks, glass or foam? what you gonna build your music studio from?
		Stars in their ears how echoes can help make a rubbish singer into a No 1 star
		Sonar so good what dolphins can teach us about ‘seeing’ with sound

Hello…hello…hello

Echoes are simply sounds reflecting back from walls, ceilings and other surfaces and arriving back moments after the original sound.

The sound of the echo depends on the distance you are away from the reflecting surface, the shape of the surface and what material the surface is made from.

The further away you are from the reflecting surface, the longer it takes for the echoes to come back to you. If an echo comes back very quickly (in less than 50-100milliseconds) you won’t be able to perceive it as separate from the original sound. Try it out .

Sound travels at around 330 metres a second, so that means you’ll perceive a separate echo if you’re 3.3m or further away from the reflecting surface.

In an enclosed space, echoes come back fairly quickly. And there are often lots of them, as sound bounces between the walls, floor and ceiling. The complex combination of these many reflected sounds is called ‘reverberation’.

Different spaces have different reverberation qualities. Which is why singing in the bath sounds different to singing in a cathedral.

Unless you take a bath in a cathedral.

Try singing in your bathroom, and compare it to singing in your lounge, or your garden. Your voice can sound very different in each of them. Most people love the sound of their own singing in the bathroom – and there’s a good reason for that…

Living in the material world

Hard materials like bricks and stones reflect sound very well.

So do tiles and porcelain, and that’s why people love to sing in the bathroom, because it makes their voices sound more powerful, richer -and sparklier on the high notes!

Soft materials like carpets, foam or baby rabbits absorb sounds and give less echo, and so do human bodies, which is why music in a

packed theatre sounds a bit different to the same music played during the rehearsal before the audience arrived.

Music and sound studios are designed to eliminate as much of the echo as possible – so the walls are covered in sound absorbing materials - fibrous materials with many pores are especially good as they absorb the sound energy turning much of it into heat energy.

It’s very rare to find a place indoors where there’s no echo at all, but these places do exist, and are called ‘anechoic chambers’. If you ever get the chance to go inside one, you’ll find it’s a very strange sensation.

When you speak, it’s a bit like talking with your fingers in your ears.

On the other hand, concert halls are designed so that the sounds from the stage reflects back to produce a good echo - or ‘acoustic’ - for the audience.

Stars in their ears

Adding a little echo, or ‘reverb’ as they say in the biz, can make music sound much richer and more pleasant to listen to and can make even the most out of tune singer sound a little bit special…

In fact, if you hear a song that has loads of echo added to the singer’s voice, chances are that without this little help they’d be as tuneful as a dolphin playing the bagpipes.

Sonar so good

Talking of dolphins, ever wondered how they find their way around in the dark ocean and how they hunt food?

Dolphins, and bats, use echo to do just this. They send out very high-pitched ultra-sound noises (too high for humans to hear) that reflect back from their environment and their potential meal.

These echoes are interpreted by their brains, so that they ‘see’ using sound.

This is called ‘echolocation’.

Once again Mother Nature has all the best ideas, and echolocation is another one we humans have borrowed for our own uses.

In 1915 Paul Langevin, a French scientist, used the idea to develop a device which is used to this day in boats and submarines to detect objects under the sea.

This is called ‘SONAR’, which stands for SOund NAvigation and Ranging. But it’s more commonly known as ‘that device that goes PING’.

And what did the dolphin get for helping us humans with this idea…? A few sardines and a blue and red ball. That’s gratitude.

Another use of ultrasound in technology is to ‘see’ pictures inside the human body.

This is used in many areas of medicine, and is perhaps best known because it’s used routinely for checking the development of babies in the womb.

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