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What happens when you throw a pebble into a pond? Some energy causes waves to travel. In this case it’s you throwing a pebble into the water.Those are visible waves. Do you know any other kinds of waves that are invisible? Sound, radio, light… ----- Meeting Notes (10/28/14 20:49) ----- Both light and sound travel in waves, but light is much faster than sound
Why do you think this happens? Answer: Light travels much faster than sound ----- Meeting Notes (10/28/14 20:49) ----- infrasound is too low for humans to hear, and ultrasound is too high for humans to hear
There are some sounds we cannot hear as humans because the sound waves are either too low pitched (too spaced apart) or too high pitched (too close together) for our ears to receive them.
Wow! Other animals can hear much higher sounds than we can! ----- Meeting Notes (10/28/14 20:28) -----
Low sounds have waves which are far apart, high sounds like ultrasound have waves that are closer together
Sound bounces off of objects and comes back to you. Have you heard echoes?
If something is close by the echo comes back quickly. If it is far away the echo takes much longer to come back.
They can listen for echoes to help them find food and use it to navigate
----- Meeting Notes (4/7/14 11:09) ----- In this drawing of a bat, you can see the nose, mouth and large ears of this bat very clearly
Bats use their special skill of echolocation to be able to "see in low light! Wish we could do that!
In Code of Claw, Gregor learns echolocation, a valuable skill for fighting in the dark.
----- Meeting Notes (4/7/14 11:09) ----- This moth can make sounds which are too high for us to hear, but they can be heard by the bat
----- Meeting Notes (4/7/14 11:09) ----- Mammals also use ultrasounds but not in the same way that bats or moths do! They use them to talk to each other, but humans cannot hear these sounds!
----- Meeting Notes (4/7/14 11:09) ----- Dolphins also use echolocation
----- Meeting Notes (4/7/14 11:09) ----- Let's take a look at how dolphins are able to use echolocation
----- Meeting Notes (4/7/14 11:09) ----- Insects also can use ultrasound for communication
What does a katydid sound like? Let's listen to their calls
----- Meeting Notes (4/7/14 11:09) ----- Mice and other rodents can also use ultrasound to communicate
----- Meeting Notes (4/7/14 11:09) ----- Frogs use ultrasound also!
What do you think this is? A Ultrasonic rodent repellent
Later on I will show you a robot that also communicates at 38 kilohertz
Everything we have been looking at so far is science, looking at nature and explaining how it works. Now lets see how technology can figure out how to make echolocation useful to us
Here’s an example of echolocation technology that is based on the echolocation science we just looked at
Just like the dolphin this device has one section that sends out ultrasonic sounds and a different one that listens for the echo (Handout)
Robots are programmed to make decisions based on input from sensors. What decisions is the robot you saw before making?
Here is where engineers took that technology that came from the science and invented a new thing
A driverless car is a robot car. A robot car is programmed to be able to move about on its own using input from sensors
University students added lots of sensors to a Ford to try to create a driverless car
Ultrasonic sensors are used to measure the position of objects very close to the vehicle, such as curbs and other vehicles when parking
This is using high frequency radar instead of ultrasound but it is the same principle
Show then pass it around
Speed of Light – Speed of Sound
• You can see a flash of Lightning almost instantly
• But it takes a while before you hear the thunder
• You can count to tell how far away it is
• Sound takes about 5 seconds to go 1 mile
What is Echolocation ?
"Echolocation is the use of sound waves
and echoes to determine where objects
are in space”
In other words, echoes help to find the
location of an object.
• Bats send out sound waves using their mouth or nose.
• When the sound hits an object, an echo comes back.
• The bat can identify an object by the sound of the echo.
Blind as a Bat?
• Most bats regularly eat flying insects.
• Bats can see as well as humans, but
echolocation is much more important to
them than their eyesight for finding food.
• Bat’s Echolocation is so precise that it can
detect an object the width of a human hair.
• Mother bats who are feeding their babies,
may catch and eat up to 4500 insects in one
They can even tell the size, shape and texture
of a tiny insect from its echo .
Some moths have developed ways to get away or confuse
bats, such as:
• Furry wings that don't reflect bat echolocation
• Sensitive membranes that can 'hear' echolocation
pulses. When the pulses are detected, the moths fly
in crazy patterns or fold their wings and dive to
confuse their hunters.
Bats using Ultrasound to Catch Prey
Click on photo to start video
The Tiger Moth Can can emit ultrasonic clicks
to "jam" a Bat's sonar!
This moth produces ultrasound not to
communicate, but as a way to protect itself. By
producing ultrasound of its own, it is able to
ward off bats by acting as a radar jammer,
confusing the bats so that the moth cannot be
located. By doing this, they add another
weapon to their survival mechanisms that also
includes poison. http://en.wikipedia.org/wiki/Arctiidae
The tiny Tarsier, only 4 inches long, can communicate
using ultrasound. The Tarsier is the only primate
known to communicate in this way.
The Dolphin uses nasal passages to make a click and sends
it through its forehead, which focuses the sounds together
into a beam before sending it into the water.
• When the sound hits an object in the water, it bounces
back to the dolphin as an echo.
• The dolphin absorbs this returning echo through its jaw.
• A passage of fat from the jaw conducts the sound to the
dolphin's inner ear
• The dolphin can tell things about the object, such as size,
shape and material.
The crickets, Arachnoscelis, is from the Katydid family. It
lives in the tropical rain forests, and can produce the
highest-frequency ultrasound of any known insect. These
sounds are emitted by the lonely male, which makes its
presence known with a burst of intense sounds. Listen to
Arachnoscelis arachnoids, a rare species of katydid from Central
Northeast of Colombia, uses elastic energy and wing movement
to reach volumes greater than 110 decibels, which is louder than
a diesel truck or a subway train.
House mice use Ultrasonic sounds to attract mates.
Rats and other rodents also use it to communicate.
The Huia Cavitympanum is the only known frog species
that can communicate using purely ultrasonic calls. This
unusual frog lives in the Philippines. These frogs can hear
sounds up to 38 kilohertz, the highest frequency any
amphibian species has been known to hear.
What are some of the
ways animals use
As you have seen, many animals use
Echolocation to help them move about in
low light and to locate food. They also use
Ultrasonic sounds to communicate.
From watching animals and through
scientific experiments, humans have
learned to use Echolocation, SONAR and
also RADAR in many different ways.
Science Technology Engineering
• Science looks at Nature and explains it
• Technology figures out how to make
• Engineering builds new things using
How Is Echolocation used by humans?
Humans cannot create or hear ultrasound, by
themselves, but we can make devices that do this
How it works:
1. A chirp is emitted from the “speaker”
2. It bounces off of an object
3. The echo returns to the microphone
4. The time it takes to travel to the object and back is used to figure out the distance
The Driverless Car is equipped with
radar sensors monitoring up to 820ft
ahead, a wide-angle video camera that
monitors lane markings. It also has 8
Ultrasonic Sensors. It can even park
itself, squeezing in to within 4in of
Read more: http://www.dailymail.co.uk/sciencetech/article-2261574/Audi-A6-
• The Tactic can help the blind move around
• It is mounted on your wrist and uses ultrasonic
sensors set above the knuckles that can pick up
the distance of objects from one inch to 10 feet
• It then translates that distance to pressure on
the wrist--the closer the object, the more
pressure on the wrist.
Read more at: http://phys.org/news/2011-09-tacit-device-safety-video.html#jCp
• The Hand Bat is a simple Do It Yourself (DIY)
device similar to the Tactic
• It uses an Arduino Microcomputer, an
ultrasonic sensor and a beeper
• It is built in a low-cost waterproof flashlight
• When you point it in different directions, it
sends out an ultrasonic sound and listens for
• It figures out the distance and tells the user
how far away an object is with different sounds
Ben Underwood was a very
special kid. He was blind
since the age of 3 when he
had to have both eyes
removed due to cancer. His
mother helped him to
believe that he could still do
mostly anything he wanted
to do even though he could
Ben learned to use clicking
sounds and echolocation in
the same way in which bats
and dolphins use it. Using
this method to avoid
obstacles, he was able to
ride bikes, play basketball
and participate in
many other activities most blind people are never
able to do. Sadly, Ben passed away in 2009 after the
Learn more: http://www.youtube.com/watch?v=AiBeLoB6CKE