I do not find the words “microphone”, “audio”, or “sound” anywhere in this pdf. Are you trying to suggest something?
Maybe OP is… hearing things?
Sorry forgot to link the audio part in the description. Somebody took the research and extended it to infer key timings from the keyboard sound
On a page labelled Ferros, I found one called KeyTap plus a related work about SSH that was labeled as an academic paper. I think he meant to submit the first. @yogthos can use this link if that’s the case.
This is a 2001 paper, suggest historical and  ?