> The acoustic structure of octaves is always the same: The frequency of a note in one octave is half the frequency of the same note in the octave above This i

> The acoustic structure of octaves is always the same: The frequency of a note in one octave is half the frequency of the same note in the octave above This is not a great definition; our understanding of frequencies came well after we were using the concept. The idea of a "string of half the length with the same tension" is much more natural, and is the easiest mechanical analogy. The discovery of this is very natural because you get sympathetic vibrations -- you can feel the other string moving when you get consonance across octaves. It shows up (along with fifths) in most other instruments -- blowing twice as hard in a flute or halving the tube size, or compressing the embouchure in brass instruments. While I don't think it's intrinsic in the human brain, it is intrinsic in most musical instruments, and it's kind of intrinsic in the way sound works, so it would be very surprising if it didn't feature in the music made by a culture, and thus work its way into the appreciation of music in general. The tests described here are interesting but might just point to the fact that there is less instrumental music (produced or listened to) in this culture than in others.