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Schools are noisy places, so Dick and Dom recruited acoustic expert Ian Butterworth to help them explore the science of sound. Some of Ian’s demonstrations required high-tech audio equipment, but here’s one that you can try for yourself at home.

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ÌýYour ears are very good at detecting what direction a noise is coming from. Here’s how to demonstrate this skill for yourself – and mess around with it!

You will need:

• An ear plug
• A large piece of cardboard you can roll into a cone-shape, plus sticky tape to secure it.
• A helper who can make a noise!

First bend the cardboard round and use the sticky tape to create a cone shape, with a hole in it that your ear can fit through comfortably. Put the ear plug in one ear, and hold the cone to your other ear. Now close your eyes and ask your helper to silently move somewhere in the room, and make a noise (eg by tapping two pens together). Point to where you think the noise is coming from. Now open your eyes and see how close you were! Try this a few times.

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Now remove the ear plug, and the cone, and try again. Close your eyes, ask your friend to move silently to a new position and make the noise again. Point … and open your eyes. How did you do? You were probably much more accurate the second time.

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What’s happening? Our ears have evolved to help us detect the direction of sound in several ways – and it explains why we have two ears, and why they’re that weird shape … Sound coming from one side of the head will be slightly louder in one ear than the other.ÌýSound coming from one side of the head will arrive at one ear slightly before the other.

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Extra information comes from the outside of our ears, the bits that stick out. These are called the ‘pinna’, and have evolved so that the sounds arriving at each ear bend round it in different ways, depending on where they’ve come from. Your inner ear then detects the resulting sound, and your brain is able to use this information to help work out the direction. (And it’s not just your ears that provide information, one of the reasons we can tell if a sound is coming from above is because the sound reflects off our shoulders!)
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Your ears are very sensitive to all of these sources of information, and your brain is able to put them all together to work out where a sound is coming from.

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When you block off the information coming from one ear, using an ear plug, and remove the information that’s added by the sound bouncing off your curvy outer ear, it becomes much harder to detect where that sound is coming from.

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Sometimes you get a similar effect if you’ve got a cold and one of your ears is blocked.