Macbooks usually have multiple mics for noise filtering. That could also be an issue.
I've tested this on my Filco Majestouch 2 with MX Browns but it barely managed to detect anything, and even then it didn't do very well. I think this is also highly dependent on the microphone used (I used the one in my Logitech webcam).
Still, I suspect that certain words, when quickly typed, have specific sounds.