Design a Noise Cancelling Device

Students develop empathy by learning about the effects of sound intensity on hearing. They do research to learn about noise-induced hearing loss (NIHL) and the sources of excessive sound that increase one’s chances of having the condition with prolonged exposure. Students learn how to measure sound intensity using a sound meter app, which they use to gather and record sound intensity data at several locations within their community. They compare their measured values to those addressed by local ordinances designed to regulate sound caused by different sources. Students use their measurements, comparisons, and research to formulate a hypothesis for the need to monitor noise levels to reduce the risk of NIHL in the community.

Learning Targets

• Students will be able to use a sound meter app to collect sound intensity data
• Students will be able to describe basic wave properties and relate them to NIHL

Essential Questions

• What is noise-induced hearing loss (NIHL) and what causes it?
• What is sound intensity and how is it measured?
• Why must people be concerned about sound intensity in the community?

Materials

• Pen or pencil
• Internet access
• Computer and/or mobile device
• Sound meter app compatible with mobile device or laptop, measures in decibels (dBAs)

LESSON PROCEDURE

1. This lesson uses a downloadable sound meter app for laptops or mobile devices. It is recommended that this be downloaded prior to the lesson.
2. Ask students to compare the relative noise levels of 2 or more places or objects in the community. Examples: malls vs airports and parks vs freeways.
3. Students should reflect on their own habits and exposure to loud sounds.
4. Have students do web research and identify 3-5 resources with information on NIHL and sound. Monitor students to ensure they access appropriate websites.
5. Students record each source and information they find in the lesson Maker Journal.
6. Review the following basic wave properties with students: amplitude, frequency, and wavelength (see Maker Journal).
7. Make sure students practice calibrating and using the sound meter apps before proceeding to the next step.
8. Students identify 3-5 different locations in their local community in which to measure and record sound intensity. Students record the locations, times, and sound measurements in the Maker Journal.
9. Students use their data and findings to formulate their own hypothesis for the need to monitor or control noise levels and how to reduce the risk of NIHL in the community.
10. Optional: Students identify local ordinances or laws, if any, that are intended to regulate noise levels and then compare them to their measured sound intensity data.

Sample teacher and student dialog

T: “Which of these two places do you think is the loudest, a crowded shopping mall or a busy airport? Explain your thinking.”

S: “Planes are louder than people, malls have loud people in them, they are about the same noise level.”

T: “We are going to do research to find information on noise-induced hearing loss, or NIHL. Then you will learn a bit about sound waves and use an app to measure sound intensity in your community. Which websites do you think might provide the best information on waves and NIHL?”

S: “Wikipedia, Google Search, online libraries.”

T: “These are useful search tools. There’s lots of info out there on various topics but sometimes we don’t always know if the info is accurate. One suggestion is to find websites that end in .org or .edu instead of .com. Videos from credible sources are also very helpful. Use your Maker journal to record your findings.”

Assessment

Student groups discuss and compare their hypotheses on the need to monitor noise levels in certain places within the community. Check Maker Journal entries for measurements and hypotheses based on the students’ findings.

Students engage in a design activity where they build capsule-like devices that hold a small object (action figure, rock, ball, etc.), akin to the classic Egg Drop activity. Students drop their capsules over multiple trials and measure the sound output with a sound meter app to identify the capsule that produces the least amount of sound. Differences in sound output are described in terms of materials, reflection, absorption, and transmission.

Learning Target

• Students will be able to describe measured sound outputs in terms of reflection, absorption, and transmission through different materials

Essential Questions

• What are some examples of objects or materials that reflect, absorb, or transmit sound?
• How does the type of material play a role in the amount of sound transmitted, absorbed, or reflected by an object that strikes the floor?

Materials

• RAFT Makerspace-in-a-Box
• Markers, pens, pencils
• Tape
• Binder clips and/or paper clips
• Scissors, staplers, hole punches, rulers
• Computers or mobile devices
• Sound meter app
• Internet access
• Other materials at facilitator’s discretion

LESSON PROCEDURE

1. If using a class-size RAFT Makerspace-in-a-Box, place materials on an accessible table or cart so students can see and choose materials for building. Make sure that each material is visible and any bundled items are separated/opened.
2. Your preferred sound meter app needs to be downloaded and calibrated for this activity ahead of time. Make sure students have ample practice doing this.
3. Give the students this scenario: Two containers are made with different materials and are loaded with the same object, and then dropped from the same height. Which container would be the loudest upon hitting the floor? (see sample dialog below)
4. Review the lesson Maker Journal pages with students, especially the criteria and constraints for building the capsule.
5. Provide ample time for students to build and test their capsule-like devices.
6. Testing should be as consistent as possible. Encourage students to consider dropping the capsule from the same height and in the same spot for each test. They should also consider keeping the sound measuring device stationary during the sound output tests.
7. Students record their sound measurements and reflect on their capsule design.
8. As a class, identify the capsule that was the least noisy based on the data and relate this to the materials used to build it. Describe instances where sound was absorbed, reflected, and/or transmitted through materials, including the floor.

Sample teacher and student dialog

T: “Suppose I have two rocks. If I put one of them in a container made mostly of foam and the other rock in a container made mostly of plastic, which one will make the loudest sound when dropped from the same height to the floor?”

S: “The one with foam because it will make a slapping noise, plastic because it will create a loud bang, foam insulates so maybe it will be quieter.”

T: “These are logical responses! Today you will explore reflection, absorption, and transmission of sound by building noise capsules, much like the containers we just talked about. You design, build and drop them and take measurements of the noise levels they produce.”

S: “Will we be told how to build them?”

T: “No. You will choose your materials to build with and come up with your own design. This helps ensure there are many different materials used throughout the class. After you measure the sound outputs we will come together and compare our data. Then we’ll see how the materials used are related to the measured outputs.”

Assessment

Students review their Maker Journal and summarize their learning in a group discussion, explaining their findings in terms of the interaction (absorption, reflection, transmission) between the measured sound outputs and the capsule designs.

Students explore the transmission of sound through different materials that are placed inside of a simple sound box. A sound source is put inside of the box, shielded by the materials to be tested and then the sound output is measured, recorded and analyzed.

Learning Target

• Students will be able to build and use sound box models to describe that waves can be transmitted through various materials.

Essential Question

• Which materials transmit the least amount of sound?

Materials

• RAFT Makerspace-in-a-Box
• Cardboard box, at least 3” x 5” x 10”
• Fabric scraps
• Small items (corks, beads, caps, dry beans, etc.)
• Paper/tissues/towels
• Yarn/string
• Packaging foam, assorted
• Cotton Balls or equivalent
• Computer or mobile device
• Internet access
• Sound source, small (phone, buzzer, bell, other)
• Sound meter app

LESSON PROCEDURE

1. If using a class-size RAFT Makerspace-in-a-Box, place materials on an accessible table or cart so students can see and choose materials for building. Make sure that each material is visible and any bundled items are separated/opened.
2. Show students two different materials that may be suitable for filling the inside of a box. Have them identify the material they think would prevent sound from escaping the box.
3. Summarize the lesson: assemble a box, fill it with a material, measure the sound output coming from a sound source inside the box. The goal is to find a material that is the best insulator against the transmission of sound through the box.
4. Review the lesson Maker Journal with students, clarifying where needed.
5. Provide ample time for students to assemble their sound boxes.
6. Students read the background information on soundproofing. They should think about this as they position and test different materials in the sound box.
7. Have students share and discuss their results and conclusions.

Sample teacher and student dialog

T: “Here are two different soft materials, packing peanuts and fabric. Which of these two materials do you think will transmit the least amount of sound? Why?”

S: “The packing peanuts because the sound will touch more of them, insulating foam prevents heat transfer so maybe it will block sound, too.”

T: “Good thinking! We’ll test these ideas by assembling a simple sound box, putting a sound source and different materials inside, and measuring the sound output through the materials to see which one transmits the least sound.”

S: “What are the steps for testing each material?”

T: “We’ll review the steps outlined in the Maker Journal for this lesson. Follow them and ask for help when needed. I suggest you test one material at a time and be consistent with how you measure the sound output. That way your data will be more reliable.”

Assessment

Conduct a whole group discussion to allow all students to share, discuss and compare their findings around materials that provided the least amount of sound transmission and then explain them in terms of attenuation and the properties of the materials that were tested.

Students experience what it is like to rely on sound to identify where an object is by listening to sounds being reflected from walls within a defined space.

Learning Targets

• Students will be able to model to describe that waves are reflected by various materials.
• Students will be able to explain how bats leverage reflected sound to survive.

Essential Questions

• What is echolocation?
• What types of materials reflect the best sound?

Materials

• Pen or pencil
• Cloth or paper to make blindfolds
• Sound source (mp3 player, small radio, or equivalent device)
• Stopwatch or equivalent

LESSON PROCEDURE

1. This lesson should be done in a large open space clear of obstacles such as furniture, and cords. Block areas leading into stairwells or sudden drops.
2. Review the concept of echolocation with students in the lesson Maker Journal.
3. Have students cut cloth or paper strips to make blindfolds, making sure they are at least 2” x 24” and can be tied or fastened behind the head.
4. Students work with a partner or group. They choose a team observer to be blindfolded and position that person at one end of the room.
5. They turn on the sound source and place it about 10 feet from the blindfolded observer.
6. Students start a stopwatch and the blindfolded observer begins to walk slowly towards the perceived position of the sound source. If there is a danger of colliding with something or falling, students can say “STOP” and guide the observer around the obstacle and then continue the round.
7. When the observer reaches the sound source, the elapsed time is recorded and the observer goes to the same starting position as before.
8. Another student holds the sound source. The blindfolded observer goes to the starting position and tries to move towards the sound source. The person holding the sound source moves about the space slowly. The goal here is to see if the observer can track the sound as it moves. Note: The sound source person should not be purposely trying to avoid or trick the observer!
9. Students repeat the procedure so each person on the team has been the observer at least one time.

Sample teacher and student dialog

T: “In this lesson you will be like a bat and use reflected sound to find a sound source. Do you know what this ability that bats have is called?”

S: “I think it is sonar, is it also called echolocating? It’s ultrasonic!”

T: “We’ll learn more about it as we go, and we’ll be blindfolded! You will work with a partner/group and measure the time it takes to locate the sound source while blindfolded!”

S: “Who will be blindfolded? Will we all do this or just one person in the group?”

T: “Each person can have a turn to be blindfolded. That person, the observer, will locate the sound source under two different conditions. First the sound source will be stationary, not moving. Then it will be held by another person who walks around slowly.”

Assessment

Students review their recorded times for both moving and stationary conditions and then develop a testable hypothesis for how to improve the times using different reflective materials. Students share their reasoning for why having a moving sound source was or was not more challenging than a stationary source.

Students demonstrate their knowledge of reflection, absorption, and transmission of sound waves by designing, building and testing a noise cancelling device as a solution for reducing noise-induced hearing loss in their own communities. They engage in each step of the design process and reiterate multiple times until their device meets the defined criteria and constraints for the project. Students share their learning in a presentation.

Design Prompt

How can the properties of different materials be used to build a noise cancelling device that minimizes the effects of sound and helps prevent noise-induced hearing loss (NIHL)?

Materials

• RAFT Makerspace-in-a-Box
• Chart paper or poster paper
• Markers, pens, pencils
• Tape
• Binder clips and/or paper clips
• Scissors, staplers, hole punches, rulers
• Computers or mobile devices
• Internet access
• Presentation Rubric

LESSON PROCEDURE

1. Present and explain the design prompt for this challenge (above).
2. Review and define the criteria and constraints listed below and these terms: iteration, prototype. Alternatively, you can define them together as a class, providing students with voice and choice.
3. Make sure students understand the expectations for the presentations outlined in the Presentation Rubric.
4. Assign student teams or assign students to specific groups.
5. Students follow steps in the design process and record their progress in the Maker Journal for this design challenge.
6. Students share and compare their design solutions, reflect on the data collection/calculations, and provide peer feedback for improvement on future iterations.

The criteria and constraints for this challenge are listed below. Criteria are the requirements for the design or its expected functions or abilities. Constraints are limitations on the design such as time, space, available materials, money, etc. The criteria and constraints are also listed in the Maker Journal pages for this challenge.

Criteria & Constraints

• Model reduces sound by 20-30%
• Model includes elements that transmit, reflect and absorb sound
• Model is portable
• Model must be built with materials provided
• Model must be completed and tested in the given time
• Model includes 8 or more different materials
• Model must be less than 2 feet wide along any dimension

Ideate Phase

During the ideation phase students should have ample time to discuss and research their ideas and potential impact. All ideas are welcome during the ideation phase, and students should be encouraged to think big. Students should capture their ideas using the Maker Journal or a digital tool (Google doc, other). Keep in mind students may return to this phase as many times as needed.

Prototype Phase

Students select one of the designs from the ideation stage to create using various materials. Initially they will have a rough prototype of the design that should eventually get better as they test it and make refinements. Students may also want to experiment with solutions that focus on changes in behavior. In this case encourage them to create a detailed plan as well as a device that will help to remind them or encourage this change in behavior. Students use the Maker Journal to draw and label their designs. Students may need to return to this phase as they iterate.

Test Phase

Students self evaluate as they test their designs in the Maker Journal. This activity should be focused on brevity and conducted at a brisk pace. Students should be going through ideas, building prototypes and evaluating their designs for at least three or four design cycles. Build time should be quick and designs should be kept simple. Students may return to this phase as they iterate.

Assessment

Student groups discuss and compare their solutions and give each other feedback on the ability of their design to reduce sound intensity and help prevent NIHL. Students also give suggestions for improvements to the design for future iterations. During the presentations, help students to focus their thinking on the data collected and interpreting the results to better define the design prompts.