This question has been bugging me for a while:
Why do we hear sound in octaves?
I'm not particularly knowledgeable about the subject of sound, but to my (somewhat limited) conception of it, octaves should not exist in nature -- wavelength/frequency/period etc. simply increases or decreases, leading me to believe that we should hear all tones as something of a single chromatic scale, but we don't. We can hear tones repeating themselves at higher and lower pitches. I'm curious as to what factor of sound waves imposes this sensation in our brains.
Any thoughts?