Infrasound and Ultrasound by Alyssa Shoultes

Infrasound and ultrasound in organisms. This section deals with how infrasound/ultrasound is used in organisms.

Dolphins Dolphins use a type of ultrasound called “sonar” to communicate with others. They also use this to make mental “maps” of murky waters they may be in, since the sonar bounces off of objects in the area and returns back to them.

From left: The workings of sonar from the dolphin’s melon to a fish From left: The workings of sonar from the dolphin’s melon to a fish. The dolphin, one animal capable of using ultrasound.

Blue Whales The blue whale uses infrasound. Being more of a solitary creature, they emit loud and long-traveling infrasound so they can keep in contact with other whales from a distance.

Bats Bats are capable of both hearing and emitting ultrasounds. They emit ultrasounds , hear insects that emit ultrasounds and figure out where they are. They, in turn, use this to catch or find their next meal. This process is called echolocation.

From left: a bat. A diagram showing how echolocation works.

Tiger Moths Tiger Moths emit ultrasounds. They use it to find a mate and to emit clicks that “jam” a bat’s echolocation from finding it.

Elephants Elephants are also capable of using infrasound. They use it to communicate between herds and to warn about predators in the area. Their lower sound and longer wavelengths allow the message to travel for several miles

Infrasound and Ultrasound in Humans This section deals with the effects of both waves on humans.

Infrasound Effects Although 20Hz is the lowest sound a human ear can pick up, certain conditions and a high volume can make infrasound audible. The addition of infrasound has been reported to cause feelings of fear. Moviemakers picked up on this and used it in several movies, most notably in the 2009 release Paranormal Activity.

Ultrasound Effects Ultrasound is used in the medical field to monitor a fetus, check for cancers, look into organs for any potential problems, among other things.

Diffraction, refraction, reflection, and constructive/destructive interference Here’s some examples of all of those said above and how they impact our daily life.

Constructive/Destructive Interference Constructive Interference Destructive Interference Placing two speakers next to each other and playing the same song with them. This is constructive interference since the two noises join together in unison and make it louder. Dead spots in a concert hall. This is destructive interference since some spots catch noise and it cancels itself out. This is avoided with proper design. Constructive/Destructive Interference

Diffraction and Refraction Hearing others speak when they pass around a corner. This is diffraction since their voices are forced to bend around a corner to be heard. Seeing a “broken” spoon in a cup of water. This is refraction since the light bends when it goes from one medium (air) to another (water) and back to the first. Diffraction and Refraction

Reflections Looking into a mirror This would be reflection since the light would bounce off of the surface (the mirror) and return back.