Prototyping an Audio-Based Language Learning Tool With a Physical Input Device

In this project, I prototyped an Android app for audio-based language learning, controlled by a custom-made smart ring.

Problem

Learning a language with audio is an underexplored topic. Certainly, you can simply listen to audio content in your target language, such as podcasts or audio books. However, such learning is not adaptive.

Now, a lot of language learning apps and materials incorporate audio, but only as a secondary channel. You still need to look at your phone or laptop in regular intervals, if not all the time. So you cannot use this while, say, walking around outside.

In this project, I wanted to build something that does both: provide adaptive learning, and be usable without looking at a device.

User Stories

As a learner, I want to practice listening in my target language — on my individual skill level.

Concept

To attack this problem, I planned to build two components: The input device, and the corresponding software.

Development

Hardware

This was the second 3D-printing project I ever did, so I did not only experiment with the interface itself, but also with CAD-modeling techniques, printer settings, components, and soldering techniques.

3D-printed finger ring, made from a cuboid shape with a circular hole, with an attached button and cables — First 3D Print

3D-printed finger ring with attached ESP — Iterated version of the ring interface, with integrated button and ESP

3D-printed finger ring with an attached ESP with integrated OLED screen displaying — Testing button interaction

Several 3D-printed components; ring and frames for electronics, attachable with screws — First experiment with heat-sinkable inserts

CAD model of part of the button ring — Ring module of the latest version, as seen in `FreeCAD`

Software

Developing the Android app proved rather frustrating.

Screenshot of the android app, showing functionality for connecting to the ring with bluetooth, the currently practiced sentence, and debug functionality — Current state of the Android app

The Product

Right now, both the software and the hardware exist, albeit as a proof of concept.

Evaluation

The biggest problem with the input device in its current iteration is how easy it is to accidentally trigger the buttons.

Also, using the setup is still clunky, mostly because of the required powerbank.

picture of a phone, headphones, the input device ring, cable and powerbank — All this is needed.

Next Steps

My next step will be to experiment with push buttons with custom 3D-printed covers.

Closing Words

This project was quite challenging from the beginning. I was quite surprised by how hard it is to find compact components, especially in regards to batteries.