Got to 21.1 quite happily, played the last one over and over again and thought my hearing must cap out at that, until curiosity kicked in and I clicked on F as a spoof answer and found out why
I know I had the most sensitive hearing of my class at school, because during an experiment on this subject I was the only one who could hear that the teacher had already got the 'annoying noise making machine' on, just as he was telling the class to put their hands up when they could first hear the noise once he'd plugged it in. I've got no idea what frequency it was at, but it made him blush when I told him it already was on and making a very annoying noise!
That said, my hearing is totally crap - I can't distinguish between certain pitches and sounds in regular speech. Last night I helped out by signing people in at a class my girlfriend takes and I couldn't understand over half the women (not just because of their strong Devonian accents either), and ended up having to ask them what their names were again. Certain sounds and words, especially soft, just blur into one and I'm left thinking there are probably two or three words or letters that could have been, hence I looked for Bs in the Vs, Js in the Ds and visa versa when taking surnames.

Give me any kind of background music, like in a club, and talk to me and I probably won't hear a word you're saying because I can't filter out and distinguish between the two sources, yet putting it down to being deaf is futile when people know how good my hearing is.

Perhaps I need my hearing tested!
Dan