As of 2012, in order to be a certified audiologist, you've got to have a doctorate degree, and won't your mother be so darned proud of you, the doctor in the family—finally!
Many audiologists earn an AuD degree (Doctor of Audiology). You can also go the route of other doctorate degrees such as Ph.D (Doctor of Philosophy) and ScD (Doctor of Science) but only from accredited universities that specialize in this sort of thing.
(Of course, all of the above means that you already earned a bachelor's degree in communication sciences and disorders or a related discipline.)
The Speech-Language-Hearing Association offers a vast amount of information regarding academic programs and certification processes.
Of course, getting a doctorate degree is no easy (not to mention cheap) endeavor. You've obviously got to have a deep, deep interest in science to begin with, a desire to help people, and of course, you’ve got to start out—and remain—committed. Becoming a doctor takes a long time. (Paying off the loans takes even longer.)