SO: v4 (Second Timers)

ELEPHANTS INFRA-SOUNDS:  If you hear a huge pipe organ play and the notes move lower and lower until you can no longer hear them, they will eventually be so low that you will be able to feel  the vibration of the unheard notes. These unheard notes are called ultra-sound and lie below 100hz. Think!

ELEPHANTS INFRA-SOUNDS: Katy Payne worked with elephants in the Portland Zoo in Oregon . She sometimes felt infrasound vibrations when she was near elephants even though she couldn’t hear anything or tell where it was coming from.. She discovered that elephants make sounds below our ability to hear in the range of 50-20 hertz.

ELEPHANTS INFRA-SOUNDS:  A person’s vocal cords are surprisingly thin at about 1/6th of an inch thick. A man’s vocal cords are about 2/3 inch long.  Less than an inch long! A woman’s vocal cords are usually just a tiny bit thinner.  This tiny DNA-coded difference is what gives women higher voices than men.

ELEPHANTS INFRA-SOUNDS:  An elephant’s vocal cords are more than 3 times longer than a person’s at about 3 inches.  And they are sixty times thicker–a whopping one inch thick!  This enables them to make deep infrasounds.

ELEPHANTS INFRA-SOUNDS: Elephants use the infrasound they can make on the large African savannas to communicate over long distances with other elephants over two miles away.  This long-distance communication can help elephants to find a mate and to search cooperatively for water and food resources.  It also keeps their babies from getting lost.

ELEPHANTS INFRA-SOUNDS:  Elephants can “hear” the ground vibrating from infrasound with their feet.  Their feet transfer the vibrations through their bones to their outer ears. This ability of foot-hearing works so well that they can hear the infrasound and foot-stomping of other elephants over six miles away.  And on a good day they can even hear helicopter blades 90 miles away!

SONAR FUN:  Sonar operators in WW2 submarines often picked up strange readings with their sonar.  In deep water, the subs would begin to detect a false bottom at around a thousand feet. Then as night fell, this mysterious “floor” would begin to rise.  

SONAR FUN: Lanternfish have a special body part called the swim bag.  This is like a tiny scuba tank within the fish that can be filled with air or emptied of air to adjust the depth at which they swim.

SONAR FUN:  In the story, the submarine sonar was reflecting off of the pressurized swim bladders of millions of the tiny lanternfish deep below the submarine.  The reason for the bladders being pressurized was the water surrounding these fish was adding pressure to the outside of these fish pressing the air inside the swim bladder.  The air inside the swim bladder was so compressed it would actually reflect the sonar. 

SONAR FUN: The rising and falling of millions of the fish in the WWll sonar story was due to the feeding patterns of the lanternfish. The fish would move upward at night to feed on tiny zooplankton which live closer to the surface. In the morning, as the sun began to rise, they would descend back down into the deep to avoid being seen by their predators. (Research if you need to)