The microphone Bit is similar to a translater. It allows you to use your voice to control your circuits. You can use it to turn sounds into light or motion, or use it with the speaker like a small megaphone!The microphone translates sound into the electronic language of littleBits. Make sure the switch is set to "sound" when you’re using it with the speaker, and "other" for all your other Bits, like LEDs and motors. The microphone also has a 3.5mm input jack so you can use your computer or mp3 player as a source for sound.