Hearrings are earrings with a message. Every time you put one on, it whispers the message to you.
The project was born as a gift idea.
The first iteration used an audio recording IC similar to those used in record-a-message greeting cards and toys. Specifically, the ISD1820. It has great battery performance, doesn’t need programming and the audio can be recorded with a mic attached to the IC directly.
I found that the audio quality was not great, even with passive filters and an amplifier attached. The audio needed to be recorded using a microphone attached to the IC directly, so tweaking the sound or adding effects was not possible either. So, I decided to use a microcontroller in the second iteration. But I wanted the user to be able to change the audio without having to reprogram anything. So, I decided to use a SAMD21 chip running UF2 bootloader so that when the hearring is plugged into a computer, it shows up as a flash drive and the user can simply drag and drop a new audio file.