I was under the notion that perfect pitch cannot be obtained after a certain age.
Valproate reopens critical-period learning of absolute pitch https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3848041/
Absolute pitch, the ability to identify or produce the pitch of a sound without a reference point, has a critical period, i.e., it can only be acquired early in life. However, research has shown that histone-deacetylase inhibitors (HDAC inhibitors) enable adult mice to establish perceptual preferences that are otherwise impossible to acquire after youth. In humans, we found that adult men who took valproate (VPA) (a HDAC inhibitor) learned to identify pitch significantly better than those taking placebo—evidence that VPA facilitated critical-period learning in the adult human brain. Importantly, this result was not due to a general change in cognitive function, but rather a specific effect on a sensory task associated with a critical-period.
However someone with "true" perfect pitch is able to detect pitches across instruments (or even a sine wave) and can distinguish minute differences in pitch; for example, someone with perfect pitch can tell that an instrument has been tuned to A415 (a typical tuning for Baroque music) instead of the standard A440.
The difference between A=415 and A=440 is not "minute" at all; it's a full half-step difference!
Also, no: absolute pitch does not necessarily confer the ability to distinguish very small differences in pitch. Many people with perfect pitch can name a given note if played, but can't reliably identify if the pitch in question is 5 or 10 cents off. This is a common misconception.
I've been practicing for two weeks, currently on G3, C4, G4, C5, mostly confident (100 correct answers) though sometimes it tricks me.
Perfect pitch means that, if someone plays a sine wave with no context, you can tell what pitch it is.
"Hey Dave, what note is that?" "Do you really want to know?" heads nod "It's a G"
One of the other tales was someone with true perfect pitch could tell the difference between A at 440 vs 441 hz.
I played it to my coworker who was working in my lab, and he said: "I'm a singer and I have perfect pitch. THat isn't A440, it's slightly low. Probably one hertz."
I checked my code and indeed, I had miscomputed the timer, it was slightly longer than it should have been. Fixed the code and he confirmed it sounded better, but not absolutely perfect.
In North America (60 Hz grid frequency), I'm not quite sure whether one would recognise it as a A# (58.3 Hz) or a B (61.8 Hz).
What bothers me about that definition is that it doesn't specify accuracy. If I play a sine wave at 498.753 Hz, how many of those decimal places will someone with perfect pitch get correct? Since classical music is based on discrete notes with intervals of at least a semitone, maybe an error of less than half a semitone is acceptable, because that's enough to sort a note into the correct bucket? But then what's the average error for people who don't have perfect pitch?
> average error for people who don't have perfect pitch
I've tried once with a kid 10 years old, she expected and answered C, D, E, while I was playing same note (unison) with long pause on harmonica. Our perception skewed by our believes. I've heard same applies to drawing — one has to learn to see.