The scientific concepts of loud and quiet are explained in this book which is one of a series intended to encourage children to explore the science of the world around them. The concepts are explained simply and are supported by activities on every page. Activities are suggested using a variety of simple tests to establish the volume of sound: the tapping of a metal spoon which has been attached to a piece of string vibrates up the chord and can be heard if pressed against an ear; the vibrations of a loudspeaker can be felt on a balloon; a speed of sound test; an experiment to prove that sound only bounces off hard objects; an activity to show how ear drums vibrate; a test to show how short strings make high notes and finally an activity which proves that the amount of air forced into an empty container determines the pitch of sound. It is hoped that these activities will explain what happens when a drum is hit, why one animal has ears on its legs, how an echo is made and what makes a rattlesnake rattle. There are "did you know" boxes on every page to test the reader's knowledge.