Sound – a set of simple experiments

The following list is a set of simple experiments that demonstrate that sound is made by vibrating objects. They could be done as a circus for the pupils or by the teacher demonstrating them and asking the children to come up and try themselves.

1. Put some small pieces of paper or rice grains on a drumhead and then hit the drum with your hand or a drumstick. The paper and the rice will vibrate (jump about).

2. Strike a cymbal and then holding it close to your ear. If you touch the cymbal with your ear you can feel the vibrations.

3. Hit a cymbal, then get hold of the edge between your finger and thumb. You can feel the vibrations stop as you grip harder and as they do the sound also stops.

4. If you stop the cymbal vibrating by putting the edge of it against your chest the sound it makes will stop as well. Link this to the damping of sound by rooms with soft walls and the echoes made from the hard stonewalls in churches.

5. Put a small folded piece of paper on a violin, guitar or cello string and then pluck or bow the string. The paper will jump about showing that the string is vibrating. You could always make a simple ‘guitar’ by two nails fixed into a piece of wood and with a rubber band stretched between them. Small pieces of paper bent over the band will jump off when the band is ‘twanged’.

6. Play a comb – you can feel the vibrations through your lips as you blow through the paper.

7. Hold a ruler down on the table with your hand so that it sticks out over the edge of the table and then twang the ruler with your other hand. You can see the ruler vibrating and as you make the ruler shorter you can hear the sound.

8. Hold your hand in front of a powerful disco type speaker. You should be able to feel the vibrations in the air. If you have an old speaker with no covering lay it down with cone facing upwards and put some small polystyrene balls in it. Now connect it to a radio or CD player and turn it on. Loud music, or speech, will make the balls jump around.

9. Play a wine glass by rubbing our finger round the edge – the glass will ‘sing’. Use a little alcohol to get rid of the grease on your finger first. You can feel the vibrations in your finger and see them if you half fill the glass with water. The water writhes and shakes because of the vibrations. (Don’t press too hard – you don’t want to break the glass).

10. Put your hand against the body of a cello, double bass or a piano while it is being played. You can feel the vibrations in the wood.

11. Twang a rubber band – you can hear a sound and also see the band vibrating.

12. Suspend a small polystyrene ball by a thread. Hit a tuning fork and then touch the ball with it. The ball should bounce backwards and forwards showing that the tuning fork is vibrating.

13. Half fill a bowl of water and touch the surface with a vibrating tuning fork. You will see water waves spreading out from the point of contact as the water surface vibrates.

14. Take a two-litre plastic bottle full of water (or lemonade) and knock it with your knuckles about half way down. You will hear a sound but also see a lovely pattern of vibrations on the water surface.

15. Hold a piece of thin card between your thumbs and blow on its edge. You should be able to make a note and will be able to feel the vibrations in your thumbs.

16. If anyone in the school has a brass instrument get them to play it. They feel the vibrations in their lips as they make a sound. Even just using the mouthpiece on its own is good enough.