Sonar and Echolocation Subject Topics: Physics and Biology

Engage

Exploring Sound Objective: Differentiate the characteristics of high frequency verses low frequency sound waves using one of the following options: Option 1: Install a free oscilloscope app on your smart device Use the oscilloscope and your vocal cords to explore sound waves at various frequencies Option 2: Go to: www.iknowthat.com/ScienceIllustrations/sound/science_desk.swf Flip the switch at the top of the interactive illustration to “Exploring Pitch and Volume” Explore sound waves at various frequencies If your students have little background knowledge or exposure to sound and sound waves, one of these two options can be used prior to beginning the Sonar and Echolocation lesson. Option 1: As homework prior to beginning this lesson, ask students who have smart phones or other smart devices with app capabilities to download a free oscilloscope app from their app store. Instruct students to explore both low and high frequency sounds using their voices. Students should observe the sound waves generated by the oscilloscope as they make low and high pitch noises. For students who do not have smart devices, here is a website with an interactive oscilloscope: http://www.humanbenchmark.com/tests/oscilloscope/index.php?active.   Option 2: Prior to beginning this lesson, ask student to explore both low and high frequency sounds using the following website: http://www.iknowthat.com/ScienceIllustrations/sound/science_desk.swf. After opening the interactive illustration, make sure the switch at the top of the illustration is flipped to “Exploring Pitch and Volume.” This can be done at home or in a school computer lab.

High Frequency vs. Low Frequency What did you learn about sound waves at with high frequency versus low frequency? What is frequency measured in? Low Frequency Waves High Frequency Waves Have student volunteers draw sound waves at high and low frequencies. You can use this opportunity to re-teach/review sound wave characteristics and vocabulary terms such as wavelength, amplitude, and intensity.

The “Name That Sound” Game Visit http://www.dosits.org/resources/all/downloads/powerpoints to listen to the sound. Use the oscilloscope on your smart device to analyze the frequency of each sound. (optional) Identify what is making the sound. Show which answer you believe is correct: A – Hold up 1 finger B – Hold up 2 fingers C – Hold up 3 fingers D – Hold up 4 fingers 5. See if you were correct. Engage Click the button to link to the “Name That Sound” file bundle on the Discovery of Sound In The Sea website. It will save a bit of time if you download the PowerPoint ahead of time. Listen to the sound powerpoint can be found at http://www.dosits.org/resources/all/downloads/powerpoints

The “Name That Sound” Game

Guiding Questions Why is sound so important in animals such as the ones you heard in the game? Why is using sound and hearing sometimes superior to using light and vision? **Remember that this is an engage activity designed to raise questions, stimulate interest and assess what prior knowledge students have about the topic. Teachers should not spend time explaining the answers to these questions. As the lesson progresses, these questions will be answers through inquiry and investigation.

Guiding Questions Why do you think animals use difference frequencies of sounds? How do you think an animal uses sound waves to locate objects? What other animals use sound waves to locate objects? **Remember that this is an engage activity designed to raise questions, stimulate interest and assess what prior knowledge students have about the topic. Teachers should not spend time explaining the answers to these questions. As the lesson progresses, these questions will be answers through inquiry and investigation.

Video: “Bats, Echolocation, & Perception” Remind students to listen for the two key vocabulary terms: echolocation and sonar

Explore

App Download For the next activity, you will need a noisemaking device. Install a free noise-maker app on your smart device. The app should have standard sounds such as “clicks,” “pings,” “rings,” or “dings” If your students do not have access to smart devices, provide them with a bell, clicker, or other noise making gadget.

Guiding Questions Can and do humans use sound to make observations about location of objects around them? How accurate are humans at using sound to echolocate? **Remember that these are questions to be answered though inquiry investigation. At this point, students should offer thoughts/answers, but the teachers should not confirm or reject answers. Let the investigation do the teaching. What body system(s) is involved in echolocation? There are two methods of echolocation, any ideas on what those might be?

Battleship: Exploring How to “See” with Ears 1 - Submarine listening for nearby battleships (triangles) 2 – Battleships emitting sounds that the submarine can detect (star) 1 – Facilitator and data recorder F R B L Although the student handout has detailed instruction on how to complete this investigation, it maybe helpful to go over the objective and explain the activity before beginning.

Front Right Left Back F R B L KEY Red dot = Sunk battleship Blue dot = Correct location but missed distance Black dot = Missed battleship F R B L Front Right Left Back Project this slide on an interactive whiteboard (or simply draw it on the board) so each student can record their data.

Active vs. Passive Acoustics Active Acoustics – a sound transmission is sent out and the echo or reflection of the sound off of an object is detected Passive Acoustics – simply listening without transmitting sound or using echoes Explain to students the basic difference in passive and active acoustics. A more in depth look at these two terms will happen in the Explain lesson.

Listening without transmitting What type of acoustic detection were you using during the investigation? Passive Listening without transmitting

Challenge Prove or disprove that humans are capable of using echolocation (active acoustics) to navigate. You will have the following supplies to complete this challenge: large, flat, smooth boards noise makers blindfold This is an optional extension investigation designed to take approximately 10 or 15 additional minutes. Provide students with large, flat, smooth boards.

Return to your seats and be prepared to discuss your findings. Time’s Up Return to your seats and be prepared to discuss your findings.

Guiding Questions Can and do humans use sound to make observations about location of objects around them? How accurate are humans at using sound to echolocate? Conclude the activity by re-visiting the Guiding Questions. Build upon student answers and clarify any misunderstandings. What body system(s) is involved in echolocation? There are two different methods of echolocation, any ideas on what those might be?

Fun Homework Assignment Using the internet, review a short video showing an example of a human using echolocation (also referred to as flash sonar) to navigate. Possible search phrases: “echolocation in humans” “echolocation Daniel Kish” Optional for students who have access to the internet.

Homework: Video Review What did you learn from the video you reviewed? What did you find most interesting? Why do you think some visually impaired humans are extremely good at using echolocation? Briefly discuss homework assignment.

Explain

What do we know about sonar and echolocation so far? Record student answers here. Ask students to share what they know so far about echolocation and sonar. Build and add to their discussion, introducing new terms and ideas. Use the Fill-in-blanks Notes Page to help students organize the information. The next slides will provide you with graphics similar to those they have on the Sonar and Echolocation Notes Page to help with the explanation.

Sonar vs Biosonar Sonar Originally an acronym SONAR which stood for SOund Navigation And Ranging It is a technique that utilizes sound waves as a tool for navigating, locating, and observing.

Sonar vs. Biosonar Biosonar Term used when animals utilize sound waves to observe and navigate their environment Often used interchangeably with the word echolocation Although echolocation is more specifically active biosonar

Let’s Fill in the Graphic Organizer Use the Notes Page Key to discuss and fill in the graphic organizer. The next slides will show larger images for discussing how each type of sonar/biosonar works.

Sonar Active Passive

Biosonar Active Passive

Key Points #1 Sound is utilized in water by humans and marine mammals, rather than light, because sound waves travel much better than light waves. In other words, it is easier to hear in the water than it is to see.

Key Points #2 Basic physics equations are used to calculate distance using active sonar. The equation is: Distance = speed of sound X time/2

Key Points #3 Echolocation was used by animals way before scientists developed sonar. The abilities of these animals are still much better than today’s sonar technologies.

Key Points #4 The fundamental technology and components of sonar were covered in this notes page. It is IMPORTANT to note that there are many types of sonar systems. Some are very complex and can provide military and others with vast amounts of information.

Basic Sonar Distance Calculation To calculate distance, you must know two things: The time it takes the sound to travel to the object in question and back again. The speed that sound travels. The data table in your notes page gives you the speed sound travels in different media at different temperature.

Basic Sonar Distance Calculation If you have a interactive whiteboard, work through the problem and fill in the blanks provided.

Let’s Listen and Calculate Listen carefully for the echo in this sound clip. It can be heard .75 seconds after the ping. If the sound is traveling at 1,510m/s, how far away is the object from the transponder? By clicking the box with the speaker, you will be directed to a Discovery of Sound in the Sea webpage on sonar. Click the play button on the sound clip half way down the page. It might be helpful to replay the sound several times so that students can hear the ping’s echo.

It’s Not Always That Simple Although we are using basic calculations to determine distance, there are many variables that affect the propagation of sound waves and must be taken into account when analyzing sonar information. These include: water/air temperature, density, absorption and scattering of sound waves and ambient noise.

Elaborate

Turning Echoes into 3-D Models What is an echosounder? How are echosounders used in mapping ocean floors and riverbeds? How can data provided by echosounders be used in “seeing” under the water? Use the diagram to for clarification of echosounders and to answer any further questions.

Turning Echoes into 3-D Models Problem: A captain of a large shipping vessel is trying to navigate down a shallow stretch of river. He claims to need a water depth of at least 5 meters to make it down the river. He has asked for a 3-D model of what the riverbed looks like so he knows exactly where to navigate. Make sure students understand the problem and the tasks they must complete. Stress the importance of using the rubric when completing the tasks.

Turning Echoes into 3-D Models Tasks: (USE THE RUBRIC p.27) Using the data provided and what you know about sonar, complete the following: Graph the sonar data provided. Create a 3-D model of the riverbed. Present your model and recommendations to the ship’s captain. Make sure students understand the problem and the tasks they must complete. Stress the importance of using the rubric when completing the tasks.

Presentation When the model is completed and meets all requirements outlined on the rubric, call me over to present the model and recommendation. Use rubric to prepare presentation. Presentations should be short and to the point.