Sonar and Echolocation

Subject Topics: Physics and Biology

Engage

Exploring Sound

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

Objective: Differentiate the characteristics of high frequency verses low frequency sound waves using one of the following options:

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

1. Visit http://www.dosits.org/resources/all/downloads/powerpoints to listen to the sound.

2. Use the oscilloscope on your smart device to analyze the frequency of each sound. (optional)

3. Identify what is making the sound.

4. 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.

The “Name That Sound” Game

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?

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?

Video: “Bats, Echolocation, & Perception”

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”

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?

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

KEY

Red dot = Sunk battleship

Blue dot = Correct location but missed distance

Black dot = Missed battleship

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

What type of acoustic detection were you using during the investigation?

PassiveListening without transmitting

ChallengeProve 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

Time’s UpReturn to your seats and be

prepared to discuss your findings.

Guiding QuestionsCan and do humans use sound to make observations about location of objects around them?

How accurate are humans at using sound to echolocate?

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”

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?

Explain

What do we know about sonar and echolocation so far?

Record student answers here.

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. BiosonarBiosonar• 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

SonarActive 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

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?

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?

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.

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:1.Graph the sonar data provided.2.Create a 3-D model of the riverbed.3.Present your model and recommendations to the ship’s captain.

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.