A Project Guide to Sound

Book excerpt: Babies crying, school bells ringing, cars roaring by, the ding signaling that a new text message has arrived . . . sounds are all around us, but how are they made? And how do we hear them? Sounds are created when air vibrates, and we hear them because our ears are specially developed to funnel in and process those vibrations. Through the activities and experiments in this book, you’ll take a hands-on look at how sounds are made and how they are heard. From salt drums to xylophones and sonic booms, you’ll have fun making music and noise—and learning a little along the way!