That's debatable Jody. If you learn it, you are always referencing other pitches. You cant learn to have perfect pitch no more than you can learn to have blue eyes. But you can learn to do the same exact thing somebody who has perfect pitch can do which is to identify notes

I took interval training in high school music class, those annoying tones that sound like telphone buttons. what interval is this.... ahhh a 5th?

The teacher explained she never had it, I never had it, and that only a tiny percentage of people actually do have perfect pitch, although many claim they do. its rare, but you dont learn ability, you learn how to use ability.

but you can learn to do the same thing somebody else has an easier time with, identify pitch