By: Savannah Dotterman

 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.

 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.

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

 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.

 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.

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

 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.

 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.

 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.