1. Sound

2. Humans perceive sound by the sense of hearing. By sound, we commonly mean the vibrations that travel through air and can be heard by humans. Presented by Brent Daigle, Ph.D. (ABD)

3. There is more sound than we can hear! If the sound vibrations are too low or too high, we cannot hear it. Even though we do not hear it, sound is all around us. Presented by Brent Daigle, Ph.D. (ABD)

4. In fact, some animals use only sound to help them know where to go find food, or sleep, or drink. What kind of animal do you know that can hear better than it can see? (Hint #1) (Hint #2) Presented by Brent Daigle, Ph.D. (ABD)

5. Echolocation - the ability to hear high frequencies, low pulses, low frequencies. Whales and Bats are examples of animals that use echolocation . Have you ever heard of elephant talk ? Presented by Brent Daigle, Ph.D. (ABD)

6. E XCELLENT GUES S  Presented by Brent Daigle, Ph.D. (ABD)

7. Presented by Brent Daigle, Ph.D. (ABD)

8. Fox Bat Presented by Brent Daigle, Ph.D. (ABD)

9. All sound moves through a medium. Sound can move through liquids (water), solids (walls), and even gases. Particles in the medium brake up the sound. The study of sound is called acoustics. Presented by Brent Daigle, Ph.D. (ABD)

10. The scientific study of underwater sound is called hydroacoustics . Presented by Brent Daigle, Ph.D. (ABD)

11. Noise is often used to refer to an unwanted sound . In science and engineering, noise refers to any kind of sound that obscures a wanted signal . Presented by Brent Daigle, Ph.D. (ABD)

12. Sound above the hearing range is known as ultrasound , and that below the hearing range as infrasound . Presented by Brent Daigle, Ph.D. (ABD)

13. Sound travels in waves. These are called sound waves . The size (or pressure) of the sound wave, depends on the material it is passing through. Presented by Brent Daigle, Ph.D. (ABD)