"I don't think it's possible to learn true perfect pitch - where you can name a note instantly, regardless of what instrument it's played on. I think it would be like teaching a color blind person to see colors. The ability is just not there. If it were possible, it would be a staple of every music shool, because it's just too useful a skill to not teach.
"I wish I had it. Musicians I've known with perfect pitch have a natural musical ability that's to die for.
"That said, I think it's possible to learn the sound of, for instance, an open A string on guitar, or to hear a note, sing it, judge it against one's lowest note in the vocal range, and then come up with a close response as to what note it is. Neither of these abilities is perfect pitch, though."
~ Avi Bortnick
(guitarist, composer; rhythm guitar and laptop on John Scofield's albums, "Uberjam," and, "Up All Night")
www.avibortnick.com