Listen Up (+Down)

If you want to start an argument between technophiles, just bring up smart speakers. An outpouring of strong opinions is all but guaranteed to follow. Some will point to the conveniences of interacting with devices by voice command. Others will focus on the privacy concerns associated with having an Internet-connected speaker in your home, sending who knows what, to who knows where, to do who knows what.

Hobbyist Andrew Peters has modified his Amazon Echo Dot in a way that allows him to keep the convenience of a smart speaker without so much concern about inviting a spy into his home. Sure, the Echo has a microphone mute button out of the box — but it is a software mute, and how do we know that we can trust it? And even if it does faithfully perform the expected function, if the power flashes off momentarily, the Echo will boot back up with the mute switched off, which may not be noticed by a user of the device.

Peters’ modification adds a hardware microphone mute switch that is neatly triggered by the buttons already present on top of the Echo. He used a tiny Arduino-compatible Seeeduino Xiao microcontroller development board, fit inside the Echo casing, to monitor the status of the volume buttons on the Echo. When the volume up and down buttons are pressed simultaneously, the microphone disconnection circuit is toggled.

The Seven microphones of the Echo all share a single data line to the CPU. By pulling this data line low with the Xiao’s GPIO pins, all communication from the microphones to the CPU is blocked. This prevents the device from gathering any audio from the microphones, which gives certainty that your conversations are private.

Peters has created a video that walks through the modification process step-by-step. If you are reasonably competent with a soldering iron, this should be a fairly simple job to complete. It does require that you physically touch the Echo each time you want to mute or unmute the microphones, however, which does make using the Echo less convenient. If you have to get up to turn the microphones back on, then ask Alexa to turn the lights on, you may decide it is just as easy to flip a light switch and cut out the middle man.

If you are looking for a privacy-preserving solution that maintains the convenience of an always-listening microphone, check out Speaker Snitch.