SparkFun's Pete Lewis Builds a Smart Pair of Ear Defenders for Music Practice and More

SparkFun's Pete Lewis has published a guide to turning ear defenders into smart, multi-functional headphones — using integrated microphones and a Bluetooth connection to mix in as much or as little ambient sound as you like.

"The original purpose of this project was to make it easy and safe to play loud music with a rock band in the basement, however, the inclusion of the natural sounds around you into your listening experience can be useful in many other situations," Lewis writes of the project. "I want to be able to lower all barriers to practicing music. The less things I have to set up, the better! My eight year old son is playing loud music more and more (acoustic drums, amplified guitar and keyboards), and I want him to be able to protect his hearing while still being able to rock out and hear the music clearly."

Lewis's project began in August last year, going through a pair of somewhat cumbersome prototypes before settling on a finished version which takes a low-cost commercial set of ear defenders with built-in speakers for an AM/FM radio tuner and gives them considerably more flexibility.

"When using this type of lawn-mowing headphones without any modification," Lewis explains, "they provide adequate sound dampening to protect your ears in extremely loud places. However, with this benefit, you also lose the ability to hear your natural surroundings clearly. Usually, it is described as sounding a bit like two pillows are held to either ear. This is because the passive sound dampening is blocking most of the high frequencies."

To solve that, Lewis came up with a trio of replacement circuit boards which sit in place of the ones provided with the ear defenders. There's a SparkFun Thing Plus ESP32 to serve as the controller, a SparkFun Audio Codec Breakout, and a custom "motherboard" which handles volume control and a 3.5mm tip-ring-sleeve input for wired audio — available as an option alongside Bluetooth audio support. There are also a pair of microphones, one per ear, chosen for their high acoustic overload point (AOP) — meaning they can pick up loud noises, like drums, without distortion.

The current version of the smart ear defenders are fully-functional, but Lewis has teased some potential upgrades for a fourth iteration — including using photogrammetry to create a 3D scan of his head in order to print fully-custom and more-comfortable ear cups, the inclusion of additional audio processing capabilities, and the addition of a pair of high-sensitivity microphones alongside the current iteration's high-AOP mics.

Lewis has published the build as a project guide on the SparkFun documentation portal.