We know about absolute and relative pitch, and that some people can recognise a note and name it. Others can sing a note, then play it, without any reference. But what is it that allows most of us - non musicians included - to hear a note, and sing it straight back. No reference except the note sound itself, and certainly no 'I know that's an F#, so I'll sing F#'.
What mechanism or whatever is it that enables us to have this propensity?
The ability to repeat sounds heard is innate (genetic), and is vital to the evolutionary survival of animals that use vocal communications with each other.
Perfect pitch is innate and developed. Most likely, it is innate in most people and rapidly lost. How we know this is that Eastern language, e.g. Chinese, is more tonal than Western languages. Far higher percentage of Chinese have perfect pitch. And there's abundant historical evidence that in past more-vocal societies, perfect pitch was common. Nowadays, perfect pitch is an oddity-- this is because it has been lost through cultural influences.
I think you'll find that its called memory. Specifically short-term memory. For a few seconds, or maybe longer for some people, you can memorize a heard pitch. After a while you forget it again. If you can retain it in long-term memory then you basically have the ability people call perfect pitch.
You do similar things without thinking about it during other activities. If you attempt to speak with an accent or try to imitate someone else's voice you are recalling what they sound like - okay maybe not pitch, but vocal characteristics nonetheless - which you are aware of them because you heard them.
A bit of background:
According to a recent study conducted by University of California professor Diana Deutsch, due to genetics, people with perfect pitch had a much larger memory span of sounds, so that they could simply remember different pitches and reproduce them accurately.
Auditory digit span has previously been identified as a genetic component, drawing the conclusion that memory abilities passed on through genes could explain why only some of the children exposed to musical training actually develop a gift for identifying tones.
“Our finding therefore shows that perfect pitch is associated with an unusually large memory span for speech sounds,” said Deutsch in a statement released by ASA, “which in turn could facilitate the development of associations between pitches and their spoken languages early in life.”
Source: http://www.huffingtonpost.com/2012/10/23/perfect-pitch-genes_n_2003151.html
It's interesting that
Absolute pitch per se might not be genetically encoded; rather, the predisposition towards a large auditory memory is.
Source: http://www.bangscience.org/2014/11/some-science-behind-singing/
So, it is simply the genetic trait of better auditory memory that leads way to developing perfect pitch. Now, non-musicians may not have the genes for a truckload of this memory, but there is enough to remember a few pitches for a short span of time.
Since analysis is not involved, my guess is this is a right brained activity. I always like to compare with colors; I happen to also have a very good color memory, in that I can see something in a store, say, Oh My that will match my bathroom perfectly, buy, it, and it does match. How do I do that? I dunno. Same with your being able to sing back a pitch you heard...you dunno but you can!! The right brain is every bit as talented as the left but usually gets ignored in our educational system; the best athletes and musicians and other experts at physical endeavors use a whole lot of right brain.
Imitation is an evolutionary trait that people have in varying degrees but all have a core amount...like monkeys imitating humans at the zoo but on our level as a social function.
