Might not be 2fa
Your PC might be generating the noise. Co-workers in the same office are likely to all get about the same "password." Or perhaps your phone could generate a very quiet noise and you leave it next to your PC mic.
How about some sort of complex graphic arriving on your phone which you could show to your webcam? A full SMS message which is then OCR'd?
Either way, there is a problem when people keep their phones and laptops together.
Perhaps there is another way. It might just work for managers. Put a small red dot on their foreheads which the webcam could pick up. The exact pattern of the blood spatter.... er... I mean... NFC transponder, could guide the miss... I mean, be detected by the webcam relaying the authentication back to the drone.