Have you learned absolute pitch?
After one year of training via the traditional tone-memory (note-naming) method, I was able to consistently recognize C through A, and with some effort recall a middle C, outside of a musical context. I was able to recall D-G with some concentration. This traditional method is currently represented by David Burge and by Nathan Becker's Tone Quiz, but the method dates back to 1899.
Once I read Gibson's book, I became convinced that perceptual differentiation would be a more effective strategy than note-naming. I stopped my absolute-pitch training at that time because I wanted to make sure that, in developing a new method, my results could be ascribed to that method alone.
I quickly lost the ability I gained of recognizing C through A, just like Meyer lost his ability in 1899. I could also no longer recall pitch sounds.
I continued using ETC v3 (Interval Loader and Chordfall) during that time, and my relative pitch skills increased from zero to the point where I was able to transcribe an audition piece into easy piano (with chords and everything!). I expect that these skills will make it easier to learn absolute pitch.
I started using Absolute Pitch Blaster in 2005, and by June 2006 I've learned to effortlessly recall a middle C without any concentration or "focusing", although when I'm tired I sometimes produce a B instead. If I think about it I can sometimes catch C's in music as well. Despite the fact that I have not used the software for a few months (while I develop a new game), this ability has not disappeared or faded even slightly.
What do you think of [insert name of absolute pitch course]? Does it work?
I hope that by reading my research on this site you will be able to judge for yourself. I have the same thing to say about all "absolute pitch" courses currently available: As of this moment, there is still no legitimate, documented, scientific evidence anywhere of anyone gaining perfect pitch as an adult. For more, please read what I wrote on the resources page.
But my musical hearing has improved! I can now name and recall pitches! Doesn't this mean it works?
Many different studies indicate that, in pitch-identification training, subjects experienced the greatest advances within the first three months and then leveled off.
Your newfound ability to perceive distinct pitch sensation is not necessarily due to any "method", but could be simply because now you are paying attention where you weren't before. Snyder's 2004 study showed that we naturally ignore characteristics of known objects. That is, we perceive whole objects and ignore their characteristics-- unless we deliberately pay attention to those characteristics.
Russo's 2003 study showed that adults were perfectly capable of learning to recognize and label tones. However, the research data clearly showed that the adults were doing so by categorization-- that is, memorizing the tones as individual sound objects. This ability may be musically relevant, but it is probably not true absolute pitch perception.