A functional model of the ear

I built this functional model to try to get my class to understand the functioning of the ear. The funnel is the pinna which directs sound waves from the air into the head. The tube represents the ear canal which takes the air vibrations deeper into the head. The cling film represents the ear drum. This converts vibrations in a gas to vibrations in a solid. The pen represents the ear bones. These amplify the signal, which is still in the form of a vibrating solid. The balloon full of water represents the cochlea where the solid vibrations turn into vibrations in a liquid. The liquid brushes hairs in the cochlea which turn the vibrations into a nerve message, hence the wire.