I heard that there are ways to tell which keys you press based on your laptop microphone. Is there a project that I could run as a proof of concept to actually experience that on my own?
They only conclusive parts of that analysis is that it is possible to recognize typed characters by the same person over time when you have previously run extended machine learning on that person's typing.
This implies that a program must be installed on their computer to really know what they're typing, making this approach totally useless for actual hacking. If a hacker was to implement this, he'd be wasting a lot of time for nothing since the keylogger would already be installed and more precise than anything else.
I understand why they don't want the public to have this code, sniffing passwords across the room is devastating.
So probably not without some serious dedication to data science.
But if you'd want to take a shot, read up on feature extraction and try replicating their diagram. Azure ML studio has a free drag-and-drop machine learning editor if i recall.