Waves and Sound

1. Waves and Sound By: Savannah Dotterman

2. Infrasound • Infrasound is a sound that is lower than 20hz. • This is the “normal” limit for human hearing. • The study of this type of sound is called infrasonic. • Infrasound sometimes results naturally from severe weather, surf, lee waves, avalanches, earthquakes, volcanoes, bolides, waterfalls, calving of icebergs, aurorae, lightning and upper-atmospheric lightning.

3. Ultrasound • Ultrasound is approximately 20 kilohertz. • This is greater than the upper limit for human hearing. • The most well known use for ultrasound is sonography to see the fetus in a pregnant woman.

4. Examples Organisms that use infrasound Organisms that use ultrasound • People use it to monitor earthquakes, charting rock, and petroleum formations below the earth • Animals perceive these waves and use them as an early warning for a natural disaster • People use it to see the fetus in a pregnant woman to make sure its healthy and developing ok • Bats use it for hunting prey • Used to find flaws in materials and to measure the thickness of objects

5. Constructive Interference • Constructive interference is when two waves combine to make a larger amplitude. To cause a constructive interference and not a destructive interference both of the waves have to have the same sign. They both either have to be negative or they both have to be positive.

6. Destructive Interference • Destructive interference is the opposite of constructive interference. When two waves combine to make a lower amplitude. It becomes lower because a negative tries to combine with a positive or a positive with a negative. Instead of the waves adding together they subtract from each other.

7. Examples Constructive interference Destructive interference • The suns rays reflect off of items creating bright rays of different shades • When two of the same sound waves combine creating a louder sound • When two different radio signals combine causing static • The suns rays reflect off of items causing dark bands with no color

8. Reflection • The reflection of a wave is when a wave is going towards an object and bounces off. • Examples of this would be a stone in a pond that a wave can not pass so instead it hits it and bounces back.

9. Defraction • The defraction of a wave is when a wave has to travel around of through something. • An example of defraction would be a somebody trying to talk to another person through a wall.

10. Refraction • Refraction is when waves change speeds because they change mediums. • An example of that would be a wave slowing down because it goes from air to liquid, or a wave speeding up because it goes from solid to liquid.