Safe and Sound
Building a Microphone for the Inside of a Beehive
Capturing useful honey bee sounds required more than simply selecting a good microphone. After researching available options and consulting with several microphone manufacturers, we selected the Knowles SPH0645LM4H, an I²S digital MEMS microphone, for our early prototype.
Space inside a hive is extremely limited, so we designed a small 16 × 16 mm printed circuit board (PCB) specifically for the microphone and its supporting electronics. As shown in the schematic, the board incorporates the microphone, connector, decoupling capacitors, resistor, and channel-selection jumper needed to interface the microphone with the monitoring system.
The microphone board also had to survive an environment electronics aren't normally designed for—inside a living honey bee colony. Bees, wax, propolis, humidity, and physical contact all presented challenges. The electronics were therefore protected with a food-grade epoxy coating while keeping the microphone's acoustic opening unobstructed.
The result was a tiny but important component: a purpose-built microphone assembly designed to listen from inside the colony while protecting both the electronics and the bees.
