Sound Wave
Light, Sound and Waves

Ear defenders

Classroom Activity for 5-11 Supporting Physics Teaching

What the Activity is for

Children think about the path which the vibrations must follow from source to detector in order for this sounds to be heard, and how to reduce the loudness of those sounds.

To make this goal orientated, and to allow for little lateral thinking, we suggest using a situation in which you wish to reduce the loudness of the sound heard.

What to Prepare

  • images of noisy workplace locations
  • images of people wearing ear defenders of various designs

What Happens During this Activity

Select a context when children would expect workers to hear loud noises (heavy vehicle drivers, – quarry workers, farmers, tanks, firework display workers, factory workers, armoured vehicle drivers).

The selection could profitably link with any one of a wide variety of topics that the children will be studying in the curriculum and so with many cross-curricular links.

Set the task of finding the most successful way of reducing the noise level reaching the workers ears.

Allowing a very wide exploration initially encourages children to explore all sorts of methods and helps them develop a deeper understanding of the physics that is taking place. You might set the class a group challenge of sketching out as many different solutions as they can in 10 minutes.

Although these activities might be seen as a design exercise, and so be primarily a Design and Technology activity, it's important that the story of the route taken by the travelling vibrations is central.

Two approaches that encourage this:

Teacher: You have the design idea – that's good. Now, what materials are you going to use and why? Can you prove that your suggestion is most successful?

Teacher: Imagine you are the science testing department of a company that is designing ear defenders for…We have been asked to find out which material will be the most suitable to use in the…part of the design.’

Discussions may well follow about the purpose of the material and about sound insulation.

You can extend this by devising and testing the proposed materials to find the one most suited to the tasks.

Further teaching ideas that embed the physics still further such as presenting the idea to the ‘Board of Directors’ of a fictional company as a recommendation. You might split the class into ‘Science Design Team’s and suggest that the contract will go to the best team.

Emphasising that the company will be investing £XXX into the recommendation will provide additional motivating context.

Children will very likely recognise that multiple factors are involved, such as being heavy or waterproof, then they can either include these in their recommendations or be encouraged to focus only on the extent to which they reduce the vibrations reaching the ear.

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