Classroom Noise Monitor

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Lesson Overview

In this lesson you’ll create an Arduino powered noise monitor for your makerspace. You’ll develop the skills needed to program the code and to connect the hardware components. You’ll learn how to connect a light strip to a small microphone. This fun, visually appealing project is a great way for youth to develop electronics and programming fundamentals while creating a showpiece for the space.
Completed Sound Meter

This lesson streamed live on September 19, 2017 at 7pm EST but you can find the recorded version below!

Supplies Needed

All of the materials needed for this project are included in our Classroom Noise Monitor project kit, the individual materials are as follows:

We’re selling the materials as a build kit. There are two different kit options: one with an Arduino and breadboard included and one without. Here are links to the product pages for each kit:

DHF Crate: Noise-o-Meter Kit

DHF Crate: Noise-o-Meter Kit (with Arduino starter kit)

Important Note Regarding the Microphone

We have experienced an issue where the pins connecting to the microphone do not maintain their contact. The microphone may need to be soldered to prevent loose connections. Our Classroom Noise-o-Meter kits contain a pre-soldered microphone.

Build Video:

Build Directions: Classroom Monitor

The Noise-o-Meter is a fun project that allows students to see a visual representation of how loud the classroom is using a small microphone that is connected to 3 LEDs by an Arduino. This is an intermediate Arduino project that has a practical application.

Here are the step by step build instructions:

Cardboard Base

Step 1: Prepare the Casing

Grab the laser cut cardboard pieces that are shown in the image to the left. These pieces will make up the box that holds the Arduino and the breadboard. Go ahead and arrange the pieces in the same manner as shown in the image. Note that not every piece is perfectly symmetric, so be sure to check that the orientation of the pieces is correct.

Building the box

Step 2: Begin Assembling the Casing

Align the tabs of the two larger pieces and connect the pieces so they form a 90 degree angle as shown in the image to the left.

Glueing the pieces

Step 3: Hot Glue the Pieces

Using a hot glue gun, glue together the pieces we just connected.

glueing the second piece

Step 4: Attach the Next Piece

Connect one of the side pieces and glue in place as shown in the image to the left.

Checking Progress

Check Your work!

Check your casing to make sure it looks like the image shown to the left.

Other side completed

Step 5: Repeat the Process For the Other Side

Connect the other side piece and glue just as you did before, the end result should look like the picture shown to the left.

The Last Side piece

Step 6: Align the Remaining Side Casing

Align the last side piece of the main casing. If you are using our project kit, this is the piece that has our logo engraved in it. Align it in the same manner shown in the image to the left. NOTE: The orientation of this piece is very important as it designed to be able to insert the Arduino’s USB port into the hole.

Connecting the last piece

Step 7: Connect the Last Side

Connect the final side piece and glue together.

thermometer piece

Step 8: Locate the Thermometer Cutout

Locate the cardboard cutout that is shaped like a thermometer because we will be attaching this piece next. Before you move on to Step 9, check Step 10 to see how the thermometer should be put on. The thermometer piece has several lasercut slots to mark where electronic components should be added. Use the images to make sure the orinetation of the thermometer will be correct

glueing the thermometer

Step 9: Glue the Thermometer

Apply hot glue to the center of the circular part of the thermometer piece.

The attached thermometer

Step 10: Attach the Thermometer

Attach the thermometer to the center of the front side. This is NOT the side that has our logo, this is the side directly across from it. Check the image to the left to see what the project should look like so far.

Inserting LED

Step 11: Insert LEDs

Now it is time to start putting in the electronic components. Let’s start with the LEDs! As you see on the thermometer piece, we have lasercut slots for the LEDs to be inserted into. These are the slots that are parallel to the ground, the slot that is perpendicular to the ground is for the microphone. Go ahead and put your 3 LEDs into the slots.

Inserted LED

Check Your Work!

This image shows what the LED should look like if it is inserted correctly. It is recommended that you keep the orientation of the LEDs consistent; so either all the long legs are on the right or all the long legs are on the left. This will make it easier when we start to wire them to the Arduino.

All the LEDs are in now

At this point your noise monitor should look similar to the one shown in this image. We made our LEDs go from green to red so that the red LED shows that the room is too loud, however you can take some creative liberties with the your LEDs.


Step 12: Prepare the Microphone

The microphone should look like the one in this image. If you are using the microphone from the kit sold by Digital Harbor Foundation, we have already soldered the three pins for you. If you bought the microphone individually, check our note about the microphone at the top of this page.

Inserting the microphone

Step 13: Insert the Microphone

Insert the microphone into the last remaining slot in the same fashion as shown in the image to the left.

arduino and breadboard

Step 14: Place Arduino and Breadboard Inside Main Casing

It is almost time to start wiring everything to the Arduino, so place the Arduino and breadboard inside the main casing.

Arduino Orientation

Check your work!

The USB port of the Arduino should fit through the hole in the back if everything has been done correctly. Check the orientation of the Arduino so that it you see the USB port just like it is shown in this image.

Wiring diagram

Step 15: Wire Everything!

Use the wiring diagram provided to wire each component to the Arduino. This part can be difficult since there are many wires in a small space. Focus on one component at a time to keep organized. It may help to open this image in a new tab to see it clearly. Simply right-click the image to the left and select “open image in new tab.”

You can also open the PDF guide by clicking here: Noise-o-Meter Circuit PDF

USB Cable connected

Step 16: Plug in the USB Cable

Final Piece

Step 17: Put On the Last Piece

Group the wires so that they all fit into the hole that is in the last piece of the casing, then connect the final piece. Do NOT glue this one in place, otherwise you will not be able get inside the casing to fix any wiring issues without destroying the casing.

Finished Casing

Check your work!

The casing should now look like this.

Code stock photo

Step 18: The Code

The only remaining step is to now upload the noise monitor program into the Arduino. We have included the code for you to copy and paste.

Navigate to this Github Gist page and copy the entire code:

Pro Tip: Make sure to replace all of the code with what you paste from the above link. One way to do this is to delete all the code in the Arduino IDE and then paste in the entirety of the project code.

Adjusting Gain

Final Adjustments

Your classroom noise monitor should now be working! It may require some small adjustments to properly tune the sensitivity of the microphone. This type of microphone has an adjustable gain, which can be changed by using a tiny screw driver. The location of the gain adjustment screw is shown in the image to the left.

Completed Sound Meter

You are Done!

Your classroom noise monitor is complete!