A door closes. A horn beeps. A crowd roars. Sound waves travel outward in all directions from the source. They can all be heard, but how? Did they travel directly to the ears? Perhaps they bounced off another object first or traveled through a different medium, changing speed along the way. Students learn how sound waves travel and about their properties, frequency, wavelength, amplitude and pitch. With a fun hands-on activity, this program illustrates the key concepts of sound and its properties. One of the 16 volumes in the Physical Science in Action series in the Schlessinger Science Library. Part of the Schlessinger Science Library in Action Collection. This title correlates to the National Science Education Standards for Physical Science-- properties and changes of properties in matter, motions and forces, and transfer of energy. This program includes a teacher's guide. (Author)