The "external monitor" phrasing makes me think you're using a laptop, which probably has its own microphone. Typically that microphone is accessible even when y

The "external monitor" phrasing makes me think you're using a laptop, which probably has its own microphone. Typically that microphone is accessible even when you're connected to an external monitor (even if the laptop is closed). You may want to visit your control panel/system preferences/whatever to see how things are configured and perhaps explicitly disable/mute the laptop mic.