Chapter 9 looks at mechanical waves and its structure, properties and how it is affected by the medium it passes through. The bulk of the chapter then focuses on sound and its characteristics including the Doppler effect. Using auditory interactives, the user investigates constructive and destructive interference along with acoustical beats. This product uses the interactive capabilities of a computer. The chapter has an embedded end-of-chapter quiz, uses graphics, animations, user interactivity or embedded video on almost all pages. This product is designed to provide bite-sized pieces of information in an effort to enhance the scientific literacy of our next generation, not to overwhelm them with sheer quantity of information. Chapter 9 section titles: What is a mechanical wave? • Wave Structure • Wave Properties • Speed of Waves in Different Mediums • The Kinetic Theory • Characteristics of Sound • Doppler Effect • Wave Interactions • Chapter Concept Map • Checking Your Understanding. This product works both on a Macintosh or PC computer.