Visualize and Hear Ultrasonic Frequencies With a Third Ear




Introduction: Visualize and Hear Ultrasonic Frequencies With a Third Ear

About: I use wearables, human augmentation, and multimodal interfaces to design and build technologies that augment how people interact with the world. I apply participatory design and qualitative methods to create s…

Continuing my interest in wearable augmentations that visualize phenomena, I designed a "third ear" that enables you to listen and/or visualize ultrasonic frequencies. For perspective, the normal frequency range for humans is around 20Hz to 20kHz. We start with a max hearing of 20kHz as babies and as adults our hearing declines to around 17kHz. With this third ear, you can detect frequencies between 20kHz to 100kHz, enabling brand-new sensing of your environment. You can hear the frequencies in real-time with a pair of wired headphones, or you can visualize the phenomena with a p5.js script. The device can also enable new perspective-taking, as you can hear frequencies similar to your dog (40kHz), your cat (64kHz), or a bat (100kHz).

In this Instructable you'll learn how to order and assemble your own ultrasonic listening device. The device works by taking those ultrasonic frequencies (20kHz - 100kHz) and transforming them into a range that we can hear (20hz - 20kHz). The device can be altered to either listen to the frequencies in real-time, record them to a computer to create visualizations, or you can design new creative ways to represent the frequencies!

If you have any questions, want to keep up with my work, or toss around ideas, please do so on my Twitter: @4Eyes6Senses. Thanks!


1x Franzis Bat Detector Kit & Manual (Should have all he PCB and components you need)

1x 9V Rechargeable Batteries

1x M3 x 5mm Screw

1x E-Z LOK Threaded Insert M3

1x 3.5mm Audio Jack Breakout

1x Elastic Adjustable Armband

1x Bone conduction Headphones (To hear the ultrasonic frequencies)

1x TRRS Audio Cable (To record the ultrasonic frequencies)

1 x Five Pin Male Header

2x 5mm Heat Shrink

1x Top Enclosure Printed in PLA (File Below)

1x Bottom Enclosure Printed in TPU (File Below)

1x Ear Enclosure Printed in TPU - File is a Remix of the "Human Ear iPhone Case" from Ruiz Brothers on Adarfruit

Step 1: Assemble Bat Detector Kit

Assemble the PCB according to the Franzis Bat detector Kit. The difference in this build is that I used male headers to solder the potentiometers to the PCB, this was especially helpful when designing the enclosure and making sure the potentiometer could fit. You also need to solder the LS- and LS+ pads to the audio jack breakout. The LS- pin goes to "Ring 2" on the breakout, and the LS+ pin connects to the "TIP", "Ring 1", and "Sleeve" pins on the breakout.

After you're done soldering, glue the audio jack breakout to the top of the PCB (Similar to Figure 1).

Step 2: Prepare Top Part of the Enclosure

To prepare the top part of the enclosure, take the threaded insert and press it into the hole at the bottom of the housing (Figure 1). use a hammer to gently push the insert into the housing until is nearly flush (Figure 2).

Step 3: Securing PCB Into the Enclosure

To Secure the housing into the enclosure, first thread the mic cable through the side of the housing (Figure 1. Then fit in the rest of the PCB in - the two potentiometers go through the two holes on the top of the enclosure. Secure the potentiometers to the housing with the two included nuts (Figure 3). Place the battery in the housing and then thread the armband through the two slits (Figure 4 & 5). Screw the Bottom of the enclosure to the top housing and use it to seal in the PCB.

Step 4: Preparing the Electret Mic and Securing the Ear

Solder the microphone cables to the electret mic (you can also add a paracord over the cable for decoration) and add heat shrink to both legs of the mic (Figure 1). Fit press the 3D printed ear onto the electret mic, it should hold in place without glue. Use hot glue to hold any loose paracord or wire in place.

Step 5: How to Visualize the Ultrasonic Frequencies

To visualize the ultrasonic frequencies, Connect a TRRS aux cable between the device's aux breakout and a computer. Use the computer to record the ultrasonic frequencies and then upload the file to the below p5.js script to visualize the frequencies:

The Script - Original visualizer was created by rjilmour

Step 6: How to Hear the Ultrasonic Frequencies

To listen to the ultrasonic frequencies I recommend using a bone-conduction headphone to connect to the aux breakout. The bone conduction creates a really interesting effect where the transformed ultrasonic frequencies are overlaid what you can hear with your biological abilities. With the device and headphones, you can explore your environment to hear what devices/things around you make sounds you can't normally hear.

Included examples of what the ultrasonic frequencies sound like are a power plant (Figure 1), a light fixture (Figure 2), and the ultrasonic frequencies coming from a ceiling (Figure 3).

Step 7: Done!

You now have your own third ear that can be used to hear or visualize ultrasonic frequencies, have fun with your new super power!!!

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    5 hours ago

    Fantastic idea. How would this go at detecting or amplifying the sound of mosquitoes?


    Reply 1 hour ago

    Not sure, It does amplify the sound but I don't think enough to hear mosquitos. It can detect when I rub my fingers together or leaves rubbing together, so maybe.

    M. DwayneS
    M. DwayneS

    12 hours ago

    Interesting, maybe I can listen to the frequency my cat uses. Hopefully, it will help me figure out why he stares at a blank wall for 10 minutes straight .


    Reply 1 hour ago

    Hehe, mine does the same. Maybe I should try and hear what's going on in the wall...


    Reply 1 hour ago

    Awesome! Never heard of that story before!


    2 days ago

    What an amazing project! All your work is so wonderful - followed here and on Twitter. Looking forward to see your other projects.


    3 days ago

    Very interesting!