Science you can see: music and hearing, talking and sound

When you listen carefully around your house or school what sounds can you hear?

Maybe… voices, the wind, cars, rain, birds, dogs, etc.

Some sounds are useful, like the telephone, the doorbell, alarm clocks.

 Sounds help us to keep safe, like the horn of a car or a bus, an ambulance siren, fire engine, railway crossing.

Some are for fun like a baby’s rattle, the radio, TV, a computer, music CDs. 

Sounds can be high and squeaky like your budgerigar, or low and booming like a truck. Some are very loud (an aeroplane taking off, or thunder), and some are very soft (the buzz of a bee).

Sounds come from vibrations, which are picked up by very small bones and hairs right inside your ears, which then send the signal off to your brain.

People have two ears and so do most animals. Cats and dogs have ears, which stick up. Lizards’ ears are simple small holes in their heads, and elephants’ ears are big and floppy.

Making good vibrations!

Take a wooden ruler and balance it about half way along on the edge of a table, and flick the free end of the wood. The ruler vibrates and makes a sound... this is a bit like the way the bones in your ear vibrate.

With an empty plastic lemonade/water bottle, blow air across the top of the bottle until you feel the whistling vibration of your breath making a humming sound. The trick is to hold your head back so the bottle rests against your chin. Add water to half fill the bottle and blow across the top. The sound is much higher isn’t it?

Of course you can make a whistling sound yourself just by blowing air through your lips. Have you ever seen people making whistling sounds with a gum leaf? Actually many types of leaf can be used or even a blade of grass, but it is not easy!!

The most fun we can have with sound is listening to music, playing musical instruments and singing. All of these sounds are the result of different vibrations. Experiment by making your own instruments and add different sounds like jingling bells, ‘bullroarers’, clapping sticks, and wobble boards.

Building your own shoe box guitar or banjo

Take a shoe box and wrap four or six rubber bands around it - across the short side is easiest, or lengthways is good too, and you now have a guitar. Strum all the strings or pluck the strings one at a time. Use different length and thickness rubber bands for different notes. Try to put them in order from the low sounds to high sounds. Check what notes you have made against the notes on an electronic keyboard or piano if you have one.

Putting together a water xylophone or piano

Fill a series of plastic bottles or metal mugs with water up to different heights. Tap them on the side with a spoon or a chopstick. Hear how the note/sound changes and goes up or down depending on how full of water the cup/bottle is. Ask someone to hold the cup, then tap the side of a plastic or metal cup as you fill it slowly with water and you will hear the sound change. With a plastic bottle the sound tends to get higher with more water, whereas with the metal or plastic cup the sound gets lower with more water. Very strange!!!

Fill a series of cups with different levels of water and tap them on the sides and listen to the range of notes. Try to sing along with the notes your tapping water instruments make. Can you play ‘Happy Birthday’, or ‘Twinkle, Twinkle Little Star’ or ‘Waltzing Matilda ‘ perhaps?

Shake, rattle and roll!

Grab some plastic or metal containers with lids. Fill each with a little bit of dry sand, or some seeds, or gum nuts, uncooked rice/pasta, or pebbles, and put the lid back on. Give them a gentle shake or roll them on the table. You can make all sorts of pleasant, and not so pleasant sounds – loud and soft.

To the beat of different drums!

Most insects have little patches all over their bodies, which act like tiny drums to help them ‘hear’ sound vibrations.

Drums can be made using empty cans, boxes, or plastic food containers, and can then be tapped with a stick. Alternatively, cover the open top of each container with plastic wrap, brown paper or a cut up balloon, then tie the thin sheets off with rubber bands. These thin coverings make quieter and mellower vibrations when tapped.

Now that you have all your instruments, record yourself performing, incorporating all the different sounds. Use an old cassette tape player or your computer – and sing or hum along.

Note: A US study has found that children who are hearing impaired are able to sense vibrations in the same part of the brain that others use for hearing.
http://www.webmd.com/news/20011128/deaf-people-can-feel-music

Sounds of the animal world

Spiders and cockroaches have hairs on their legs, which help them ‘hear’ by sensing vibrations. Lots of animals make sounds to ‘talk’ or communicate with each other. Grasshoppers and some other insects make chirping noises by rubbing two parts of their body together – typically the leg on to the abdomen. This is a bit like humans clapping their hands perhaps!

For humans – we use our voice to speak, whisper, sing or even shout.

To do this we need:

• air from our lungs
• our vocal cords which vibrate and make the sounds from pockets of air
• our cheeks, tongue, and lips to fine tune the sounds.

Of course our brains learn to do all this very much automatically. Singers become skilled at using their voice accurately to sing a wide range of notes.

Dogs bark and cats meow using vocal cords like us. They can only really vary the tone of their noises. Birds use a slightly different method of calling and hence can ‘sing’. They have a bony structure and membranes in their neck through which the air vibrates, and this makes very pleasant sounds. Some birds like parrots and budgerigars can ‘mimic’ human words.

Dolphins make lots of interesting sounds, whistling and clicking tunefully, using the airsacs below their blow holes. Again it is vibrating air, which makes the sound. Then, there are the beautiful whale’s ‘songs’. We don’t yet know how whales produce these complex sound patterns under water. 

Protecting your hearing

So that we can hear all the sounds of the world we need to protect our ears from very loud noises. Workers sometimes use ear plugs or ear muffs. Earphones on radios, or computers or iPods should not be turned up too loud.

Washing your ears and drying them with a towel after a swim or a shower keeps them clean and healthy.

Things that help people hear better include microphones, Cochlear Implants (the ‘bionic ear’), and hearing aids.

Check on YouTube for funny videos of sound effects, e.g. look up ‘cornflour monsters’. Watch loud sounds from a speaker system make flour paste twist into weird shapes.

Important note: All activities are designed to be performed under the supervision of a responsible adult who is aware of any conditions, which might preclude the safe participation of the child with regard to allergies to food, or other household or environmental agents.

Article written by Kathy Andrewartha (B.App.Sci., M.Sc., B.A., Grad Dip. Info. Sci.). Kathy studied Biochemistry at Swinburne and La Trobe Universities and has worked on research topics involving both plants and animals. She enjoys teaching science at all levels. She particularly likes presenting science to young children, and is passionate about stimulating active learning and analytical thinking about scientific topics.