Down
| 1. | The bouncing back or change in direction of a wave after it strikes a barrier or an object. This may also be called an echo. |
| 2. | A machine that converts an electrical signal into a sound wave with an increase in loudness. |
| 3. | Sound waves can travel through the air as well as some liquids and ____. |
| 4. | A space that contains no air or other matter through which sound waves cannot travel. |
| 5. | The bending of waves as they pass through an opening or around the edge of an object. |
| 6. | A machine that sends out sounds waves and uses the waves that are reflected back. This is used to help detect underwater objects. |
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Across
| 1. | The area where there are fewer particles than normal as a result of being near something that is vibrating. |
| 7. | A structure in humans that contains the vocal cords and vibrates to produce sounds. |
| 8. | As sound waves move, the ____ of the sound waves spread over a larger area. |
| 9. | The form in which sound energy moves from one place to another. |
| 10. | The part of the human body used for hearing. |
| 11. | A sound that is repeated because the sound wave reflected or bounced back from a distant object. |
| 12. | Energy that is produced by vibrations and travels in the form of waves. |
| 13. | Two or more sound waves that overlap. |
| 14. | The process of using reflected sound waves to find objects. Bats, dolphins, and some other animals use this to find food and avoid danger. |
| 15. | The rapid back-and-forth movement of matter. |
| 16. | The area where particles or air are pushed closer together as a result of being near something that is vibrating. |
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