What do you think perfect pitch is?
I don’t know. I’m asking you.
My guitar tuner is set to 440 hz. I’m guessing that’s supposed to be perfect pitch.
But what’s that relative to? It’s relative to the next harmonious note up or down the scale. Not to anything our ears hear right?
I like things slightly out of tune.
Perfect pitch, as the term is typically used, means a person has an exceptionally good pitch resolution, so that if they hear (for example) 440 Hz, they can say what the pitch was to within an unusually accurate margin, usually measured by keyboard notes. A person with “perfect pitch” hearing 440Hz would say it is an “A”. This does not necessarily mean that they can distinguish without any other clues 440Hz from 440.1Hz. The difference between notes on a piano in terms of Hertz is, um (let’s see . . . calculating . . . )
. . . about 6% of a difference in Hertz. So, a person with perfect pitch can determine a pitch at least that accurately, as in 440Hz +- 6% or 440 Hz +- 26Hz. I’m not sure just how much more accurate some people with exceptional pitch accuracy are than this.
This is relative to a person’s intuitive pitch memory, so that a person can say what they think a pitch is upon hearing it once, without any other input.
However, when we add harmony, our brains have more tools to use. If we were to compare two pitches sounding simultaneously in harmony, for example 440Hz and 440.1Hz, we would clearly hear the difference between the two from the interference patterns in the sound waves. This isn’t perfect pitch; it’s totally different in terms of brain functions. It’s a kind of auditory pattern recognition. These two frequencies will produce, at a minimum (depending on the waveforms) an interference pattern of 0.1Hz. We are exceptionally good at picking out very subtle interference patterns in sound; I suspect it’s part of our language abilities. This kind of processing allows for much, much more fine identification of differences between pitches than the accuracy with which any person with “perfect pitch” would be able to identify any one pitch. 0.1Hz is slow: one cycle per 10 seconds, but definitely noticeable.
It’s probably also worth mentioning that everyone perceives pitch slightly differently in each ear, with individual variation. One ear will hear a pitch ever-so-slightly sharper than the other (and the other will, of course, hear a pitch being ever-so-slightly flatter). Our brains “correct” this without us thinking about it, but the effect can sometimes be heard by simply finding a constant pitch and plugging one ear then the other and seeing if your perception of the pitch changes. Not to mention differences in sensitivity to frequencies in different auditory ranges, some natural, some caused by uneven hearing damage between the ears.
Does that answer your question?