Audio captcha confusion

[kestrell]

I just tried to leave a comment on Tor.com and although there was an audio captcha, it was not as accessible as it could be. It is one of those audio captchas that gives a snippet of audio, say six or seven words, and though I gave it a couple of tries, I didn't seem to enter either of the two words which actually made up the captcha.
I have run into this system of audio captcha on a number of sites, this isn't meant to pick on Tor.com.
However, I have yet to get this sort of audio captcha to work.
Is there some secret formula to which two words are the captcha words?