Instructions
Plug in your computer microphone. Depending on the device, it may require a 3.5 mm audio jack or simply a USB connection. Refer to your specific microphone's documentation if you have trouble setting it up.
Test your microphone by running Windows Sound Recorder. Find the program by clicking on the Start menu and typing "Sound Recorder" in the programs window. If you are running Windows XP or older, click the Start menu, then select "Programs," "Accessories," "Entertainment" and "Sound Recorder."
Start No$GBA and play your game. The system should detect and use your computer microphone automatically.