Aimed at a general audience, this film is about the structure and function of the ear. The film opens with images of human responses to sound; shots of a level crossing closing; a man listening to car engine; a mother jumping as she hears her baby cry; a woman on the telephone to her husband. Commentary explains that sound is composed of waves that enter the ear. Animated diagrams show the sound waves hitting the ear drum, moving the chain of tiny bones in the middle ear; the hammer; the anvil and the stirrup, collectively known as the ossicles. Live action footage shows the vibration of the eardrum and ossicles. The inner ear; diagrams show the bony labrinth, the vestibular apparatus and the structure of the cochlea and the nerves reaching the brain. There is an explanation of how a hearing aid works.