Two tones an octave apart are
perceived as having a kindred relationship - as being, in a sense, "the
same note". This recognition of similarities for tones an octave apart is
and was applying to any major musical culture all over the globe since the
beginning of the history of man.
The sense of pitch associated with a
tone has two different attributes: the frequency of the tone, the ”height”,
and the chroma, which is a quality shared by all notes described by a particular
letter. (Bachem 1950) Thus C2 and C3 are separated in
pitch by an octave, they both have the same chroma
- that associated with all C’s. They are in the same family.
In one interpretation of the pattern
recognition theory of pitch, the brain searches for a distribution of peaks
along the basilar membrane corresponding to a harmonic series of vibrations. On
this basis, the fact that C2 and C3 evoke almost the same
sensation can be readily understood.