Which of the following is NOT considered an audio device?

A monitor is primarily considered a display device rather than an audio device because its main function is to visually present information, such as images and text, from a computer. While certain monitors may have built-in speakers to output audio, their primary role is to provide visual output rather than audio output or input.

In contrast, microphones, speakers, and audio interfaces are all designed specifically for handling audio. Microphones capture sound and convert it into an electrical signal, speakers play back audio by converting electrical signals into sound, and audio interfaces serve as the bridge connecting microphones and instruments to a computer, ensuring that audio input and output is managed effectively. Thus, the monitor stands out as the option that does not align with the category of audio devices.