A friend of mine posted a blog entry about a tone-deafness test. Not being a musician, I tried it with the standard speakers on my PC, which are the usual junk. I scored 80.6%, which pleasantly surprised me. For me I think it was more pattern recognition than tone detection. I’m also guessing that since there were only 36 questions, for most people the statistical error for a single test is over +/- 5%. So I’d guess I’m really between 76-86%.
Another thing to note is that the web-test results are biased high by people cheating a little. They say in controlled laboratory testing the highest they got was 88%. So my friend, who is impeccably honest, did really well with 86.1%.