There is an Arduino Nano to run the speech recognition algorithm and a MAX9814 microphone amplifier to capture the voice commands. However, the beauty of [Peter’s] approach, lies in his software ...

You can also use the on-board audio output jack to connect to your own amplifier/speaker set! This unit has a maximum recording time of 680 seconds, and a minimum recording time of 341 seconds.

[GreatScott] achieved this with a microphone and amplifier circuit, that was then piped into one of the analog pins of the Arduino Pro Micro at the heart of the build.