I have very slight hearing loss in one ear (10 DB shift from right to left) which means that I am very sensitive to any background sound at all, so actually, it's very hard for me to listen to the Google audio CAPTCHA without nearly blowing my ears out with such a high volume. I guess I'm glad it works out better for others, but really, I'm just pissed off with all these efforts to mistreat human beings for absolutely no reason whatsoever. It's offensive, annoying, and wrong. IMO.

Because Google visual CAPTCHAs can't usually be operated using these CAPTCHA solver solutions, it is actually worth it for me to use Rumola (one such system) against the visual CAPTCHA on any property, and with greater speed, than any Google CAPTCHA, which will always be audio if a blind person must solve it independently. So actually I fear the Google CAPTCHA more than the non-Google ones.

In the past, sound CAPTCHAs have typically been the weakness and have generally been attacked with a higher success rate than visual ones. But really all CAPTCHAs are "security by obscurity", since they rely on what essentially amounts to a recognition barrier that machines usually exhibit in pattern recognition. The problem, of course, is that since an algorithm creates the CAPTCHAs, it's not long that an algorithm learns how to filter out the noise, and in fact Google have successfully attacked their own CAPTCHAs in the past; it's a big reason why they are now deploying the "invisible" CAPTCHAs they now are.