This is fascinating, Larry.

I have had excellent relative pitch as long as I can remember. (Can't always produce the exact pitch vocally, but that's a separate skill.)

I have doubted whether "perfect" pitch (meaning absolute) really existed, and suspected that there were other cues that people were using to identify a pitch. But after playing highland bagpipes for a while I found I could pick a bagpipe A (closer to concert Bb) out of thin air pretty reliably, and then pitch from there. But not go directly to a random note.

What really puzzles me is the mechanism that seems to put absolute pitch in conflict with relative pitch. I can sing (and on most of my instruments, play) in pretty much any key, no matter how well I know the tune in the "normal" key. It's great to have that transposition ability -- I can do it on the fly if not too sophisticated -- especially when accompanying various singers with their different comfortable ranges. If we start in one key, and someone says, "too high, let's go down a third," it gives me no trouble.

So obviously my brain works in "relative mode." Even though I might know what pitch belongs to a written note, it doesn't bother me to substitute another one. I can look at a chord progression written in Bb and play it in E, and sing the melody off a lead sheet at the same time with no problems. Now that's not to say one pitch is as good as another; once established in a key I can stay there quite solidly. Relative pitch both vertically and longitudinally, I guess.

I've known people who claimed they couldn't sing along with "Happy Birthday" if someone started it in another key. I always thought they were showing off somehow. But apparently this is a real effect, and I just can't imagine having that problem.

So -- Larry, or anyone else with established absolute pitch:
If you are used to singing "Happy Birthday" in C, for example, would it be easier for you to sing along in Gb if I wrote it out for you? Or would the aural memory of the "correct" pitch still try to throw you off?

Curious.
-Glenn