tester wrote:But when I recall last one hour and last two hours, and last 4 hours - then I have no such sense of octaves
I think "recall" is the operative word here.
One can easily see how an innate sense of relative pitch and of short "rhythmic" time periods would have come about....
- How does a spider tell between a gust of wind and freshly trapped prey? Easy, he uses his built-in FFT to analyse the harmonic structure of the web vibrations looking for their distinctive spectra. Lots of bursts of high frequencies at short intervals means that something is well and truly snared!!
In fact, the inner ear and nerve centres equate very nicely to the way that an FFT divides frequencies into 'bins' (critical bands) - the data is in the frequency domain at a level way below consciousness.
Likewise with consonance and dissonance - the most consonant sounds are so closely related that they can sound much like a single sound source with complex spectrum, whereas dissonance immediately flags up "SH*T, there's more than one of them!!".
All pretty damned useful survival adaptations, even for the simplest of life forms.
But perceiving longer times? The environment gives sufficient clues for most creatures to know when it's time to migrate, get horny etc.. Perception of time on that level only makes sense for creatures which plan a future based on an analysis of the past (cause and effect) - and even then, the order of events is much more significant than having a precise temporal datum. Surely a much more recent evolutionary adaption, and one that pre-supposes a certain degree of sentience.
We don't really "sense" long periods of time - we sense the effects ("getting cold again") and deduce time's passing ("Winter coming"). My favourite example is waking up full of the memory of a great dream in which hours of "experiences" happened only to find that it was a twenty minute nap - so did my mind age more than my body?
Hence, "time flies when you're having fun" and "a watched kettle never boils" - the more conscious of time we are, the more of it there is. When we try to "recall" the time since an event, we are relying on a memory that is tuned to remember events and the way they relate to each other - and the content of those memories inevitably clouds our judgment.
OTOH, with music, the time periods will more closely resemble the rhythms of a heartbeat, or the co-ordination of muscles for movement - more in tune with our 'primal' instincts ("Listen, that's definitely a sabre-tooth cat coming this way - and it's coming damn fast!).
Even within music, our perception of time is not so rigid. With a fixed BPM, it is still possible to create the perception of tempo changes. For example, a 'busier' beat (more events in the same amount of time) will appear slower than a very sparse one, and small amount of shuffle (faster) and swing (slower) also have this effect.