Absolute Pitch research, ear training and more
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 mainly by Prolobe, 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 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.
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. We naturally ignore characteristics of known objects (Snyder 2004). That is, we perceive whole objects and ignore their characteristics-- unless we deliberately pay attention to those characteristics.
Adults are perfectly capable of learning to recognize and label tones (Russo 2003). However, the adults were clearly doing so by memorizing the tones as individual sounds, and could not recognize anything in musical context. This ability may be helpful for certain purposes, but does not seem to be true absolute pitch perception.