Actually, I think the noise proves his point. The fact that adding so much noise was necessary means computers are pretty good at solving that problem, and it has to be made next to impossible for humans before computers can no longer solve it either.

Wow, I could barely make out the audio captcha!

But you could still make it out, right?

I couldn't figure out the audio captcha. People who are blind probably have better hearing, so maybe it's easier for them.

I've heard a lot of anecdotal evidence that young blind people have better-than-average hearing, but what about the elderly?

I'm not sure anyone I know over 70 years old could pass either of those captchas. I guess the only consolation is that most people that age often have younger people sign up for them.

I certainly couldn't. Perhaps they rely on blind people having heightened auditory senses.

Wow, that's incredible how much noise they've added. I couldn't make it out myself. Its bordering on unusable IMHO.

Still, I wouldn't be surprised if a computer could get 1 in 4, which is plenty to be effective. They're still only using the 10 digits for the signal.