Olaf Lets an ESP32 Listen to the Music

The joys of overengineering a simple gift. [Joren] wanted to create a dress for his daughter’s fourth birthday that would react with lights in sequence for a song from Frozen. The dress and an LED strip, along with a digital microphone and a battery were easy to procure. But how to make it all work? An ESP32 did the trick.

While the project’s name–Olaf–sounds like it was from Frozen, according to the GitHub page it actually means Overly Lightweight Acoustic Fingerprinting. Right. However, as the name implies, it can learn to identify any sound you want.

One interesting twist. The code is in C, so running it through Emscripten allows the code to run in your browser and you can watch it work alongside a YouTube video of the movie. You can see in the image above that the fingerprint screen gets red dots until it matches the audio and then the dots turn green, indicating a match.

Even if you don’t want a magic Frozen dress, the code on GitHub could be a good starting point for developing audio-sensitive applications.