2023-08-31 | By Lulzbot

License: See Original Project 3D Printer

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Guide by Lulzbot

Acoustic Amplification Creations

Description

Have you ever considered why acoustic guitars are louder without the use of electricity? Or why ‎putting a phone in a glass cup makes the music playing louder? These instances are examples of ‎manipulating and directing sound waves, something we do with our speakers, with our hands, and in ‎our everyday lives! But can we design an acoustic device to do this intentionally?‎

Introduction

Lesson Overview:‎

Through this lesson, we will investigate the fundamental properties of sound waves and how they ‎travel through the air. After considering what creates sound, we will determine how we can create ‎devices to manipulate it!‎

Utilizing an engineering design process, students will research, brainstorm, design, and fabricate their ‎own amplification devices within a variety of specifications and constraints through a real world design ‎challenge! We’ve all made efforts to both dampen and increase sounds in the world around us, from ‎muting an alarm clock to cupping our hands over our mouth to help us shout. In this lesson, students ‎will create technology that can assist in such a situation!‎

Through their research and designed solutions, students will utilize computer aided design software, ‎or CAD, to assist in creating a model prototype solution that will be produced using 3D printers! ‎Students will then have the opportunity to test and evaluate their solutions under real-world ‎specifications and constraints of a design challenge. Through this activity, our students will not only ‎learn about sound, but also create devices that interact with it!‎

Utilizing an Engineering Design Process:‎

An Engineering Design Process, or design loop, is a method used by scientists, designers, and ‎engineers to develop solutions to our everyday problems. Through a design loop, students will ‎develop skills in problem solving as they brainstorm solutions and work to create a prototype through ‎hands-on activities. ‎

Design loops come in many shapes and sizes, but none are ever truly ending. The “last” step of any ‎design loop is redesign, or reflection, where we look at what we’ve learned in our developed ‎prototype to improve upon its design. Not being afraid of failure is a powerful concept that leads to ‎greater success and implementation of problem solving.‎

Assorted 3D Printed Amplification Prototype Examples and a LulzBot TAZ SideKick 747 3D Printer

Lesson Objectives:‎

• Students will identify the properties of sound waves and how sound travels through the air ‎‎
• Students will identify a situation where sound amplification may be needed or changed‎
• Students will create an acoustic or mechanical device that amplifies sound waves
• Students will utilize an engineering design process to develop their own solutions to a real-world ‎problem
• Students will utilize computer aided design (CAD) software to create a 3D model that can be ‎produced on a 3D printer
• Students will understand how 3D printers work and how they are used in an industrial setting‎
• Students will be able to safely apply prototyping techniques to construct designed solutions to real-‎world problems

Materials:‎

This is a list of materials each student will need to complete this lesson: ‎

• Pencils, rulers, drawing paper‎
• Computer or tablet with Internet access
• Computer Aided Design (CAD) software
• 3D Printer and Filament
• Assorted non-3D printed materials to include in prototyping such as hot glue, tape, cardboard tubes, ‎plastic cups, or rubber bands (optional)‎
• Click here for sample models shown throughout this lesson‎

Modifications:‎

In addition to this lesson plan, see our One Page Brief [PDF] that can be used to guide students ‎through the lesson. Additional examples as to how this lesson could be modified are:‎

• Offer additional tools and materials to construct prototypes such as cardboard tubes, paper cups, or ‎hot glue to combine with 3D printed parts
• Students could be challenged to create a prototype for a specific device, like their own phone - or a ‎more generic situation, like any phone - to reflect real-world product design situations and decision ‎making
• Incorporating electronic measuring equipment like a decibel meter or programmed micro controllers ‎such as a microbit or Arduino to interact with sound may allow greater cross-curricular connections to ‎be made‎
• Students could design a various assortment of amplification devices, choose constraints to foster ‎creativity and cater to the available resources within your instructional space!‎

Considerations:‎

Based upon the age of your students, introduce the concepts of amplitude, pitch, frequency, sound ‎waves, and rapid prototyping techniques using terms and concepts familiar to their prior experiences ‎and needs. ‎

Offering opportunities to allow for personal interest and passions to be included in prototype design ‎may foster higher engagement and interest among students. Consider creating real-world scenarios, ‎such as wishing our phones were louder when playing audio in a large room or creating devices to ‎amplify our voices in a crowd, to provide students with ideas and content they can relate to. Choose ‎constraints and content that fit the needs and interests of your students.‎

Proper safety procedures should be introduced to students when working in any makerspace or lab ‎environment. When students are around machines such as 3D printers, or using tools to cut or glue ‎materials, students must be informed of potential hazards and taught how to use these resources ‎safely. For reference, see the safety resources offered by ITEEA. ‎

Assessments:‎

Opportunities for formative assessments will take place through observations and discussions ‎between students as they interact with the content in this lesson. For summative assessment, we ‎recommend utilizing a rubric to assess how a student was able to apply the engineering design process ‎to solve an open-ended problem. Example Rubric - PDF

Essential Questions:‎

• How does sound travel through the air?‎‎
• Why does sound get louder or quieter depending on physical materials it passes through or around?‎‎
• How can we create an acoustic device that changes the volume from an instrument, electronic ‎device, or our own voices?‎‎
• How can we use technology to design a solution to a real-world problem? ‎

This prototype solution is designed to reduced or muffle the amplification of an acoustic guitar rather ‎than increase it!

‎Printed on a LulzBot TAZ SideKick 747 using Flexible TPE Filament

Identify the Problem

How Does Sound Travel?‎

We are surrounded by sounds. From the soft clicking of our keyboards to the alarms and sirens of an ‎emergency vehicle, objects create and emit sound that we can hear and recognize. In the Acoustic ‎Amplification Creations challenge, students will be creating unplugged, acoustic devices that can ‎manipulate and change the amplification of sound waves!‎

Sound travels through a medium, such as air or water, as a wave. These sound waves travel by shaking, ‎or vibrating, atoms or molecules as they travel. While all sound waves cause these vibrations as they ‎travel, there are differences between them which is why we hear different sounds, tones, and ‎volumes!‎

Each sound wave has its own unique pattern that can usually be described by its amplitude, or height ‎of the wave, which determines how loud the sound is to us when we hear it. Amplitude is measured in ‎decibels (dBA). A wave can also be described by its frequency or pitch, which changes the tone we can ‎hear as our ears interact with the sound wave. The frequency of a sound wave is defined by the ‎number of waves that pass by a point within a second. Frequency is measured in hertz (Hz). ‎

Sound waves are sometimes called compression waves because they create areas of compression and ‎rarefaction as they change pressure levels while traveling through the air. Waves with a higher ‎amplitude have greater energy as they travel which makes them louder across a longer distance. ‎When a sound wave collides with a solid object, the waves can either be reflected, diffused, or ‎absorbed. This means that sound is a physical reaction which relies on movement of molecules, ‎something that can be manipulated using physical devices, like your hands! Through the physical ‎properties of sound, we can create devices that manipulate the amplitude of a sound wave to make it ‎louder or quieter as we develop our own prototype solutions!‎

Identify the Problem

Have you ever tried to make your phone louder by putting it in a glass cup? Or cupped your hands over ‎your mouth as you tried to get someone’s attention from across the room? These physical actions are ‎attempts to change the amplitude of a sound wave, just like a hollow-body acoustic guitar! ‎

Using an engineering design process and modern prototyping techniques, can you create a device that ‎changes the amplification of a mobile device, instrument, or your voice more effectively and with ‎greater ease? Consider ergonomic and aesthetic factors in your design, as well as the following ‎constraints to guide you through this challenge:‎

• Your prototype must change the amplifications of sound waves from a chosen real-word situation (a ‎mobile phone, voice, instrument, etc.)
• Your prototype solution should consider ergonomics and aesthetics in the design as you create a ‎prototype solution that reflects real-world product design
• Your 3D Model build volume may not exceed 36 in³ ‎‎
• You have 1 day to brainstorm, 3 days to build, and 1 day to test & evaluate‎

Resources:‎

Offer examples of different sound waves to compare how we hear amplitude and frequency.‎

Objectives:‎

• Students will identify the properties of sound waves
• Students will identify how sound waves travel through the air and interact with the objects ‎around us
• Students will identify how sound waves can be created, or manipulated

Teacher Instructions: ‎

Encourage open discussion as students explore how sound works and how sound waves travel ‎through the air. Creating sound can be fun, as can manipulating it using different materials and objects!‎

The concepts of amplitude, frequency, and sound can be differentiated to fit the understandings, ‎abilities, and needs of any age group. Consider appropriate definitions and labs for your students as ‎you introduce fundamental topics. See the “Modifications” and “Considerations” sections in the lesson ‎introduction for more info and ideas. ‎

Objectives:‎

Students will be able to identify the role specifications and constraints play in a real-world design ‎challenge.‎

Teacher Instructions: ‎

There is no one answer to any solution, nor is there one specific set of constraints for any design ‎challenge. See examples for how to adapt and modify the specifications and constraints of this design ‎challenge under the “Modifications” and “Considerations” section of the lesson introduction. ‎

Prototype Megaphone Amplification Device

printed on a LulzBot Mini 2 using PLA

Brainstorm Possible Solutions

Why Solutions and Not Solution?‎

The second step of our Engineering Design Process is “Brainstorm Possible Solutions.” A key part of ‎this step is solutions being plural, meaning more than one. Why do designers and engineers think of ‎more than one way to solve a problem?‎

Teacher Instructions: ‎

Adapt key phrases, concepts, and terms to best fit your students’ needs. Main idea is there is NEVER ‎any one solution to a problem. If possible, provide an example that relates to your students’ lives, like ‎all of their different shoes, or phones, or video game consoles. Emphasize the importance of variety ‎and why we must, as designers, think of as many ideas as possible.‎

Brainstorming Our Solutions ‎

As we work to think of different ways to solve this problem, there are a few things we can consider ‎assisting in our design. The first is to determine what sound wave we wish to amplify. Do you want to ‎make your phone louder when playing music? Or perhaps amplify a movie being played on a tablet? ‎What about making your voice louder at a sporting event? Or perhaps reduce or change the ‎amplification of your musical instrument? Any of these real-world scenarios could be improved ‎through the creation of your prototype solution!‎

An effective strategy to designing a solution is to research and learn from existing solutions. ‎Investigate existing devices that serve a similar purpose to the one you wish to create, as well as ‎consider how they could be changed or improved. ‎

After researching existing solutions, begin to design your own unique amplification device! Remember ‎to consider the specifications and constraints of the design challenge as you brainstorm different ‎potential prototype solutions to this problem. The constraints may not only guide your decision making, ‎but also ensure you have a viable solution to solve the identified problem. ‎

Thumbnail sketches are a great way to think of many ideas quickly without getting caught up on the ‎details. Once you’ve completed the thumbnail sketches, narrow your choices down as you create your ‎final design. For your final sketch, create a clear design that is neat and labeled. Consider drawing your ‎design from multiple views (front, top, side, or isometric) to better portray your ideas.‎

Teacher Instructions: ‎

Emphasize coming up with as many ideas as possible as students will tend to want to go with their first ‎idea. Also reiterate the real-world specifications and constraints of the design challenge and ensure ‎students are factoring them into their designed solution. The detail in technical drawings can be ‎modified based on age and prior skill of students, as can resources provided to students in order to ‎support the brainstorming stage. Offering additional materials to work with, such as cardboard tubes ‎or paper cups, may foster greater creativity while also offering mediums students are familiar with. ‎Inform students of what materials they can use as they begin to design their prototype solutions. See ‎the “Modifications” and “Considerations” section of the lesson introduction for more examples on ‎how to modify this design challenge to cater to available resources.‎

Objectives:‎

Students will obtain a greater understanding of how the engineering design processed is used to solve ‎real-world problems. ‎

Brainstorming different possible solutions using the lesson one page design brief document

Resources:‎

• One Page Design Brief Document [PDF]
• Thumbnail Sketching Document [PDF]
• Technical Drawing Paper [PDF]‎

Objectives:‎

• Students will be able to identify various situations sound could or should be amplified
• Students will apply research and brainstorming techniques to develop multiple solutions
• Students may consider increase or decreasing amplification in a real-world setting
• Students will use technical drawing skills to plan and share their ideas with others

Develop A Prototype

What is 3D Printing? ‎

Step 3 of the engineering design process is all about constructing our prototype solution! In this step, ‎we are going to get hands-on with software and machinery to create our final designs.‎

One of the key prototyping machines used by today’s professional designers, engineers, and scientists ‎is a 3D printer. There are a lot of different types of 3D printers out there, but all 3D printers create ‎physical objects you can touch, and hold based on a 3D design or digital model. Some 3D printers melt ‎rolls of plastic into the model, while others use light to harden a liquid resin. There are even 3D printers ‎that can print concrete, metal, or living cell tissue!

LulzBot 3D printers use the fused deposition modeling process (FDM) that feeds and melts spools of ‎plastic through a nozzle, kind of like glue traveling through a hot glue gun. The plastic is fed, or ‎extruded, layer by layer to create the model designed in computer aided design (CAD) software. Once ‎we design our amplification device models in CAD software, we will be able to send them to 3D ‎printers to be manufactured! ‎

Teacher Instructions: ‎

Introducing and over viewing the resources available for prototyping before beginning construction is ‎key. Make sure your students know what resources are available, as well as how to use them safely. ‎Introduce any additional resources available for prototyping during this step (see Modifications in ‎lesson introduction.)‎

Developing our 3D Models ‎

Now that we’ve brainstormed our prototype amplification devices, it is time to begin to fabricate them! ‎But before we can 3D print our parts; we need a 3D design. To create this, we will use computer aided ‎design software, or CAD. There’s plenty of great free CAD programs out there, we recommend ‎Tinkercad, FreeCAD, Fusion360, or OnShape for students.

‎As you are creating a prototype that changes the amplification of a particular device or instance, like a ‎phone for example, it is important your prototype can fit the device you wish to interact with. One ‎way to ensure this is by taking accurate measurements, or dimensions, and including them in your ‎design. If you want a phone to fit into a stand, or to be able comfortably hold your prototype in your ‎hands, take accurate measurements of objects to ensure they fit within your design. Also consider ‎creating a mock simulated assembly of all 3D printed and non-3D printed parts in CAD software before ‎production. ‎

It’s also always a good idea to include tolerances, or “wiggle room”, in your design too! Tolerances can ‎be added to your dimensions to ensure things fit together or are not too tight after printing as 3D ‎printer material tends to shrink during production. In general, adding 1/16” to dimensions acts as a ‎general tolerance when working with PLA. Note, model shrinking and required tolerances can vary ‎based on filament, printer, printing conditions, and print orientation. ‎

Objectives:‎

Students will be able to identify how 3D printers work, and how to use them safely.‎

Resources:‎

• Computer or Tablet
• USB Mouse (Recommended)‎
• CAD Software & Guiding Tutorials

Objectives:‎

Students will utilize CAD Software to create a 3D model of their designed solutions.‎

Teacher Instructions: ‎

Students may better understand the purpose of CAD after being initially introduced to rapid ‎prototyping production machinery. For beginners, experimentation is key when learning the basics of ‎CAD software. Encourage patience and offer tutorials or techniques to support learners. Working with ‎a USB mouse often makes CAD easier to use.‎

‎‎

3D Printing Modular Components for a Hybrid‎ Amplification Prototype on a LulzBotTAZ SideKick 747 using PLA

‎

Simulating a mock assembly of a hybrid amplification prototype using shape generators in the ‎Tinkercad design application

Develop A Prototype

Printing!‎

Once students have completed their designs, it’s time to download and prepare them to use Cura. ‎Cura is not a CAD program in that it allows you to design your models. Instead, Cura “slices” models’ ‎layer by layer to create a program file, or Gcode file, for the 3D printer to read. This Gcode file is a set ‎of directions that the 3D printer follows as it prints your model. ‎

In general, we recommend PLA filament for most classroom uses as it’s a safe plastic to print in schools ‎and prints easily in nearly any setting. PLA works well for most applications, but you may also want to ‎consider TPU or TPE filament to create flexible parts devices that interact with musical instruments or ‎need to be durable and particularly strong. LulzBot 3D printers are able to print countless types of rigid ‎and flexible filaments right out the box! In addition to considering filament choices, we must also ‎optimize our print settings to fit the needs of our student’s models. The first consideration is print ‎quality:‎

• High Speed has a default layer height of 0.38mm and works best to create models that do not ‎require lots of detail quickly
• Standard has a default layer height of 0.25mm and is the best compromise between speed and ‎detail for parts that need to fit together at a faster speed
• High Detail has a default layer height of 0.18mm and is best for printing detailed and delicate ‎models slowly. ‎

Additionally, if you students have any overhangs, you should consider Support Material and Bed ‎Adhesion settings. Support material is automatically drawn by Cura to fill any gaps or structural flaws ‎while bed adhesion will allow for greater contact to be made between the part and print bed by ‎increasing surface area. After the model is printed, supports and brims can be carefully removed by ‎peeling it off of the model. ‎

Constructing our Prototypes ‎

In the final part of this stage in the engineering design process, we must construct our prototypes ‎after all parts have been 3D printed. Depending on available resources and the specifications and ‎constraints of the challenge, this step may involve assembling 3D printed parts together, cutting and ‎creating sound horns from paper cups, or gluing 3D printed parts to non-3D printed materials. ‎

Time needed for construction will vary based on the available resources and materials students have ‎to build with. ‎

Remember, proper safety procedures should be introduced to students when working in any ‎makerspace or lab environment. When students are around machines such as 3D printers, or using ‎tools to cut or glue materials, students must be informed of potential hazards and taught how to use ‎these resources safely. For reference, see the safety resources offered by ITEEA.‎

Objectives:‎

Students will understand how 3D models designed in CAD are prepared and sent to 3D printers for ‎manufacturing.‎

Teacher Instructions: ‎

Depending on your student age group and classroom resources, the teacher may need to slice the ‎models for the students. Ensure proper settings are chosen for selected filament and model quality. ‎Reference LulzBot guides and tutorials for assistance.‎

Discussing Gcode is a good lesson in itself! Gcode is a list of directions for the machines to follow and ‎can be read using a basic text program. Did you know early CNC machines required people to write ‎Gcode manually? Luckily, we have Cura for that now! ‎

Resources:‎

Materials and tools for prototype construction.‎

Objectives:‎

Students will use available resources and apply proper safety techniques to construct their prototype ‎solutions.‎

Teacher Instructions: ‎

Available resources and additional materials will vary based upon the specifications and constraints of ‎the design challenge. Consider offering cardboard tubes, paper cups, popsicle sticks, or hot glue to ‎enhance amplification device design and creation in an open-ended design challenge. For more ‎examples, see the “Modifications” and “Considerations” sections in the lesson introduction. ‎

Safety is key. Ensure all students have been trained to use any available tools or resources and ‎organize your room to ensure these resources can be monitored accordingly. ‎

Preparing a prototype to be 3D printed on a LulzBot Mini 2 in PLA with a brim using the Cura LulzBot ‎Edition slicing application

Constructing a prototype amplification device using a variety of materials in combination with 3D ‎printed components‎

Testing Criteria ‎

In this stage of the design process, it is time to get hands-on with our designed prototype solutions in ‎order to determine their effectiveness in solving the defined problem of the Acoustic Amplification ‎Creations design challenge!‎

During the testing stages of the engineering design process, we must place our prototype solutions ‎into a real-world environment to determine how they perform. Testing situations may vary between ‎amplification devices as each student created their own unique designs for various circumstances. In ‎any testing situation, it is important to get a baseline to compare our prototypes to in order to ‎determine their success. Using a decibel measuring device, such as a decibel meter, a DIY device coded ‎using a micro controller, or a decibel measuring app on a smart phone, measure the pre-existing ‎amplitude prior to implementing your prototype solution. Once recorded, incorporate your prototype ‎device into the testing environment and measure the amplitude again. Did it increase or decrease as ‎expected?‎

During this stage, consider making multiple attempts from various simulated situations to obtain an ‎average baseline, as well as to get a more accurate sense of how your prototype performs. Consider ‎manipulating or modifying your prototype during testing to get the best possible results. ‎

Evaluation Criteria

After the real-world testing stages have concluded, we must review the data collected and determine ‎if our prototype solution was successful in manipulating the amplification of sound waves. Consider ‎the following questions:‎

• Did the sound waves increase or decrease in amplitude as expected during testing?‎‎
• Were you able to interact with your prototype through a real-world setting as expected?‎

These guiding questions may allow for students to consider the successes of their designed solutions ‎as well as areas that can be improved upon in a more meaningful manner. ‎

Offer an opportunity for students to present their findings to their classmates, as well as an ‎opportunity to receive suggestions from their peers as to how their prototype solutions could be ‎changed or improved in terms of performance, ergonomics, and aesthetics. Offer guidelines and ‎expectations for sharing feedback to help guide students through productive and meaningful ‎conversations as needed. Emphasize that there is no one way to solve any problem, as we discovered ‎in the early stages of this lesson when looking at existing solutions. Each student found their own ‎unique way to solve this problem.‎

Resources:‎

Planning document [PDF], or notebook to record findings and discoveries during testing stages of the ‎design process.‎

Objectives:‎

Students will apply the engineering design process as they test the performance of their design ‎prototype solutions.‎

Teacher Instructions: ‎

Challenge students to think critically as they compare their designed solutions to the identified ‎problem, as well as existing solutions. Remind students that these are PROTOTYPES, not finished ‎models and that failure or room for improvement is expected and GOOD when designing solutions to ‎real-world problems. ‎

Resources:‎

Planning document, Notebook, or presentation software and Internet-enabled devices.‎

Objectives:‎

• Students consider the data collected during testing to determine the effectiveness of their ‎designed prototype solutions
• Students will review and share their data with their peers as they provide and collect ‎constructive feedback with one another

Teacher Instructions: ‎

Create connections between the constructed prototype solutions existing solutions in the real world. ‎Encourage students to think critically as to how their prototypes compare to these products. ‎

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Testing the performance of an acoustic amplification speaker using a smart phone and decibel ‎measuring device

Printed on a LulzBot TAZ SideKick 747 using PLA

Redesign

No design is perfect, nor is it ever truly finished. As new technology is developed, improvements like ‎cost, speed, performance, or aesthetics can always be made. When considering redesign, we must ‎look at both the successes and failures of our prototypes. A failed design does not mean we failed; it ‎means we have room to improve upon for the next prototype solution! ‎

Consider collected data from testing and evaluating your prototype amplification devices, as well the ‎feedback obtained through observations and from your peers. What worked well? What could be ‎improved? Could you improve its ergonomics or aesthetics to make it better reflect a professional ‎quality product? Record your thoughts and create a sketch of an improved prototype design with ‎changes you would make to allow your prototype to better meet the evaluation criteria and solve our ‎real-world problem more effectively. Your sketch should be neat and label the changes you are ‎making to improve your solution’s performance.‎

Resources:‎

• Planning document or Drawing Paper [PDF]‎

Objectives:‎

Students will utilize the engineering design process to reflect and improve upon their designs as they ‎create a proposed redesigned solution.‎

Teacher Instructions: ‎

Stress the importance of failure in design and engineering. No one enjoys failing, or not doing well, but ‎the redesign step is a chance to reflect on both the good and bad of our designed solutions. ‎Additionally, we can use observations made from other solutions as we create a proposed redesign ‎with everything we’ve learned. ‎

Drawn and written redesign activities both work well with varying learning styles, we recommend a ‎combination of the two. If time permits, students may use CAD to make a 3D model of their ‎redesigned solution or even attempt to create a new solution entirely.‎

Removing the brim off of a 3D printed prototype model

printed on a LulzBot Mini 2 using PLA