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What is Echolocation?

What is Echolocation?. Echolocation, also called bio sonar, is used by several kinds of animals, such as bats, dolphins, and whales, that need sound to locate food or determine the environment.

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What is Echolocation?

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  1. What is Echolocation? • Echolocation, also called bio sonar, is used by several kinds of animals, such as bats, dolphins, and whales, that need sound to locate food or determine the environment. • They put out sounds and listen for them to echo back, so they can locate and identify objects, such as food, and their surroundings. Image source: http://www.vox.com/2014/11/7/7171119/blind-sonar-echolocation

  2. Before We can Understand Echolocation, We Need to Look at What Sound Is. • Sound is energy caused by a back and forth movement - vibrations. • Soundwaves cause molecules around them to vibrate and move them along. This is called having a “medium” to travel through, such as air (O2) or water (H2O). • As soundwaves cause vibrations, they can keep going until they run out of energy.

  3. Picture a stone thrown into a still body of water. • The rings of waves expand indefinitely; sound travels the same way, in waves. Image source: http://www.dreamstime.com/royalty-free-stock-photography-throwing-rocks-image5875767

  4. Image source: http://wallpapercave.com/sound-wave-wallpaper

  5. Image source: http://www.colorado.edu/physics/phys2010/phys2010LabMan2000/2010labhtml/Lab6/EXP6LAB99.html

  6. Now we know that in order for sound to travel, there has to be something (a medium) with molecules for it to travel through. • Space has a small fraction of these Molecules. They are spread too far apart to move soundwaves from one atom to another, therefore, there is no sound in space. Image source: http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/1-is-there-sound-in-space.html

  7. Amplitude and Frequency • All sound waves are produced the same way - travel through a medium by making molecules shake back and forth. • But the actual sound waves can be different. • We know that we hear different sounds; loud, quiet, high-pitched squeaks, and low-pitched rumbles; even two instruments playing exactly the same note will produce sound waves that can be different. • Why?

  8. There are two things that happen to sound waves that make them very different when we hear them: amplitude and frequency • The volume of sound (loud or quiet) is the AMPLITUDE (intensity). It tells us how tall the soundwave is (height). • The pitch (sound quality), example: soprano singers make fast sound waves that result in a high note, while bass singers make slow waves that make a lower note, is the FREQUENCY

  9. Amplitude: how high the wave is • Frequency: how often the wave is formed AMPLITUDE FREQUENCY Image source: http://dpaudioa.blogspot.com/2011/02/frequency-amplitude-and-eq.html

  10. CRITICAL THINKING QUESTIONS: Can sound travel under the water? Yes or no and why? If so, does it travel faster or slower than in air and why? Is there sound on the moon? Yes or no and explain your answer. Discuss amplitude and frequency. Think about hot air and cold air. Do you think sound moves faster through hot or cold air? Why – explain your answer. What is thunder ? Think about it.

  11. Activities 1a, 1b, and 1c

  12. Lunch

  13. Reflection and Absorption • Have you ever been in a room with nothing in it? Does it sound echo-y? What is going on? Do you have the same experience in a room that has drapes, carpets, and furniture? • Sound is REFLECTED (bounced back to the source) when it hits a solid surface, such as a wall, creating an echo. • This doesn’t happen in a room that has soft materials, such as a sofa, carpet and curtains – the soft furnishings ABSORP (take in) the sound.

  14. Image source: https://www.isover-technical-insulation.com/industry/applications/acoustic-insulation-industry

  15. Activities 2a and 2b

  16. Echolocation • Now we know how sound is made, how it travels, and that it is reflected when bounced off of a solid object, absorbed by soft materials, and transmitted until it dies out without anything to obstruct it. • When we started this lesson, we were introduced to “ECHOLOCATION” (echo=reflected sound; location = place or position) = is the use of sound waves and echoes to determine where objects are in space (water or air). • Many animals in the wild are unable to rely only on their vision to move around and hunt. They use echolocation to survive.

  17. Bats: • Have an interesting way of looking at their world; they are nocturnal, which means they are most active at night. • Have poor vision and depend on their ears to find their way around in the dark; navigate using ultrasound frequencies, which are higher than the normal human range of audibility (high pitch, move fast). • As their soundwaves pass through air, they reflect off solid surfaces, are absorbed by soft surfaces and transmit when unobstructed. • Reflected soundwaves (bounce back to bat) allow bats to find food, help them avoid obstacles in their path, and lets them communicate with other bats.

  18. Detect obstacles Find food – can discern whether the moth is flying away from it or toward it from the amplitude (sound is louder if the object is coming closer and softer if it’s moving away). Image source: http://images.frompo.com/i/bat-echo-location

  19. The process of echolocation is very natural for the bat, who doesn’t care that he is “as blind as a bat.” He can see with his ears  Image source: http://www.nybats.org.uk/page18.htm

  20. Dolphins: • Use echolocation to navigate their surroundings, locate prey, communicate, and protect themselves from predators in murky waters or where there is no sunlight. • In deep dark waters, their have very poor sense of sight, but they do not need it because they can detect and chase fast prey through the emission of sounds. • Echolocation by dolphins occurs when the dolphin produces sound waves from an area of their head above their eyes called the respiratory cavities.

  21. 1. Red: the top of the head is where the nasal sacs are (nose) 2. Purple: blowhole is a canal where the dolphin takes in and exhales air 3. Yellow: structures within this cavity, phonic (monkey) lips (similar to human vocal chords) vibrate by pushing air out from lungs, to make clicks , whistles, and other sounds Light green: these vibrations made from phonic lips are passed to bursa 5. Orange: bursa transmit vibrations to the dolphin forebrain, the melon Image source: https://notafishblog.wordpress.com/2014/10/20/consider-the-hippo/

  22. Image source: http://www.kevkurtz.com/his-blog/2016/11/2/how-do-dolphins-sleep

  23. The melon concentrates vibrations and emits (sends) them forward, like beams. • Once the emission is released forward, the sound waves reflect back from objects that are in the water. • Image source: https://matthewhardcastle.wordpress.com/2012/09/30/hello-world/

  24. Bat and Dolphin Echolocation: https://www.youtube.com/watch?v=7ppBf-GlKkA

  25. Humans: • Human echolocation is the ability of humans to detect objects in their environment by sensing echoes from those objects, by actively creating sounds – for example, by tapping their canes, lightly stomping their foot, snapping their fingers, or making clicking noises with their mouths – people trained to orient by echolocation can interpret the sound waves reflected by nearby objects, accurately identifying their location and size. https://www.youtube.com/watch?v=WHYCs8xtzUI

  26. Activity 3

  27. Sonar • Scientists observed natural echolocation in animals, like bats and whales, and found ways to adapt these concepts for humans to explore the seas. • Human echolocation devices are referred to as SONAR, Sound Navigation and Ranging. • There are two types of sonar: • Active: uses echo reflection to determine objects, range, et al • Passive: used only to detect sounds coming toward them

  28. We know humans use echolocation for blind people to navigate through their lives, but there are many other uses for sonar: • Locating underwater objects like sunken ships, planes, and treasure, or to locate hazards. Image source: http://www.oicinc.com/history_sonars.html

  29. Detecting submarines, or submarines use it to navigate the seas. Image source: https://teamuv.org/tag/sonar/

  30. Ocean floor mapping to develop nautical charts. Image source: http://keywordsuggest.org/gallery/563351.html

  31. Fishing Image source: http://imgkid.com/fishing-sonar-screen.shtml Image source: https://www.fishfinders.info/best-fish-finder-reviews

  32. Others: • -used in industry to detect defects in products • -in medicine as ultrasounds Image source: http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/waves_earth/ultrasound_infrasoundrev2.shtml Image source: http://www.abclawcenters.com/practice-areas/prenatal-birth-injuries/labor-and-delivery-complications-and-errors/placenta-previa/

  33. References: 1. https://familymaven.io/kidsactivities/parenting/teaching-kids-how-sound-is-made---683kC-U0OEHaFGvSoQqQ/ 2. https://acousticalsolutions.com/back-to-school-sound-experiments-for-kids/ 3. https://www.teachengineering.org/activities/view/cub_soundandlight_lesson4_activity1 4. https://www.explainthatstuff.com/sound.html 5. https://www.reference.com/hobbies-games/drum-produce-sound-a917cc846d6ca176 6. Jeanette A. Thomas, Cynthia F. Moss, Marianne Vater. Echolocation in Bats and Dolphins. University of Chicago Press, 2004 7. https://seaworld.org/en/animal-info/animal-infobooks/bottlenose-dolphins/communication-and-echolocation

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