Resources: Rubber band, clingfilm, card, cylinder, bendy straw, ping-pong ball, bowl of water, tape, scissors, speaker, the handout and a music clip.
From KS2, the students should have have a basic understanding of the parts of the ear and their functions in hearing, including the outer ear, middle ear, inner ear and the auditory nerve.
Whilst playing a range of sounds, ask the students to cup their hands around their ears, then pin their ears back. They are to describe how each action affects their hearing. Can they explain why these differences occur?
Ask the students to work through the presentation, answering questions as they go. Introduce the parts of the ear and explain how sound travels through the ear. Once complete, the students can watch the mission assignment video and then build their own human ear and test it. There are reflection and evaluation questions on the worksheet that the students can answer.
Career Film: Camilla Barrow is a project manager for Crossrail. Camilla uses sound detection in her job. Camilla gives an update about how the Crossrail development is progressing,
Expert Film #1: Jon uses a large model of a human ear to explain how it works to receive sounds.
Expert Film #2: Mike Linley talks about the collection of microphones he has used when filming.
The students will build a descriptive model ear. The ear is not an accurate representation of the human ear; instead, it aims to teach students how our ears work.
Support: Technicians can build a model ear so the students can see one in the classroom before they start to build. Alternatively, models could be part-built with the students only having to complete a few sections. There are support questions on the worksheet.
Challenge: Ask the students: if animals that can be trained - such as dogs - do not understand language, how can they still respond to our commands? The students should be able to communicate that they can detect the sounds and that the brain can process the information. However, an animal such as a dog is listening more to pitch and intonation than the actual words being used.
Review findings from the practical and then complete the questions on the end of lesson assessment quiz.
Sound is basically a vibration that travels through matter. Matter can be anything from a gas to a liquid and a solid. To reach our ears, the sound waves must travel through the medium first. When movement takes place, a vibration is initiated. For example, when a guitar string is strummed, a vibration is created. This vibration is passed on from molecule to molecule until it reaches our ears. The vibration makes the air around the object vibrate. Each air particle will bump into its neighbouring air particle until a sound wave is created. Our ears then hear these vibrations as different sounds.
Sound itself travels in longitudinal waves. Longitudinal waves vibrate in the same direction of travel. These types of waves have frequencies that determine the pitch of the sound. They also have amplitudes, which determine the volume. These types of waves travel a lot quicker in solids than they do in any other medium. They rely on matter to propagate. For example, sound needs the vibrations of the molecules to move and different mediums will speed that up or slow it down. The speed of the wave is dependent on the density of the medium through which it is travelling. A sound wave will travel a lot quicker through steel than it does through water.
Human ears are responsible for detecting sound. They will convert the sound waves into electrical impulses so that the brain can translate the information. These waves will initially move through the ear canal and eventually cause both the eardrum and the bones of the middle ear (malleus, incus and stapes) to vibrate. These vibrations later travel through to the cochlea where they are later changed into electrical impulses for processing by the human brain. This is how we process and detect sound.