[almostnormal]

> While I concede that most people think of perfect pitch as something that is instilled in some way in early childhood rather than achievable through practice, I guess I would ask those commenters... why do you think the latter is fundamentally different, or is using some separate mechanism?

As soon as having learned some relative pitch, it becomes very difficult to train absolute pitch. One single note a day. For the second note the brain will switch to relative mode, and there's no progress on absolute. Forcing the ear/brain to run in absolute mode seems possible, but is difficult consistently enough to practice absolute.

Source: Experimenting with my own ability (or lack thereof).