II. Fill in the blanks with the correct answer. which also vibrates because of air. 11. What makes a sound? 12. This is a medium where sound travels Slowly. 13. In each of our ears, we have a very sensitive membrane called the 14. It is an example of a transducer, a device that changes information from one form to another. 15. It is an echo-sounding device or a technique that uses sound. 16. Where does sound travel fastest? propagation to detect objects on or under the surface of the water. 17. Which of the following materials absorbs most of the energy of sound waves? 18. How is sound transmitted or heard? 19. What do we call a series of sounds caused by the reflection of sound waves from a surface back to the listener? 20. Sound is produced by making​