Activity 1.7 - Hearing sounds

• Understanding that the ear detects sound vibrations
• Understanding how the human ear works
• Understanding that human hearing range lays between 20 and 20000 vibrations per second

Hand out Classroom Material: Hearing Sound and let students read and answer questions 1 to 3. Then discuss how the human ear works. To visualize it you can use an animation, for example: http://www.sciencekids.co.nz/videos/humanbody/ear.html.

There is a possibility for cross-curricular links here. It would be a good opportunity to link to the biology topic of the ear.

Here students also could be engaged in technological design as they could design and build their own simple models of the human eardrum.

As the last activity let students read question 4. Start a discussion about what they can hear and what they cannot hear – and lead onto hearing ranges of humans and animals.

• When a compression in a sound wave in the air hits the eardrum, in which direction does the eardrum move?
• In which direction does the eardrum moves when an expansion of a sound wave arises?
• If you hear a bird sing with a frequency of 2000 vibrations per second, how many times per second does the eardrum vibrates?
• How does the ear response to a loud sound differ from its response to a soft sound?
• How does the ear response to a high sound differ from its response to a low sound?
• Why sounds aren't as loud when you cover your ear?
• How does the ear strengthen the sound waves so that they will be strong enough to affect the liquid of the inner ear?
• Why you do not hear a dog whistle while your dog does?