Each participant also wore small microphones in their ear canals that were sensitive enough to pick up the slight vibrations created when the eardrum sways back and forth. (sciencedaily.com)
The bottom is where you'll find a microUSB port and a very small microphone port. (ubergizmo.com)
Many laptops come with internal mics, but if yours does not, or if you have a desktop computer, most electronics stores or big - box retailers sell small microphones for about $ 20. (educationworld.com)