  Nowadays, CAPTCHAs are computer generated tests that human can pass but
current computer systems can not. They have common usage in various web
services in order to be able to detect a human from computer programs
autonomously. In this way, owners can protect their web services from bots. In
addition to visual CAPTCHAs which consist of distorted images, mostly test
images, that a user must write some description about that image, there are a
significant amount of audio CAPTCHAs as well. Briefly, audio CAPTCHAs are sound
files which consist of human sound under heavy noise where the speaker
pronounces a bunch of digits consecutively. Generally, in those sound files,
there are some periodic and non-periodic noises to get difficult to recognize
them with a program but not for a human listener. We gathered numerous randomly
collected audio file to train and then test them using our SVM algorithm to be
able to extract digits out of each conversation.
