Also, the thing about high frequencies and sharp edges lead to a contradiction: babies are more round than adults and produce higher pitched sounds, this is almost universal across all species.
There are other tentative explanations, such as how the vocal tract acts when producing these sounds, with "bouba" sounds being the result of smoother movement more reminiscent of a round shape.
"kiki" is not just higher pitched, it is also "shaped" differently if you look at the sound envelope, with, as expected, sharper transitions.
So to me, the mystery is still there. Is is the kind of thing that sounds obvious, in the same way that kiki sounds obviously sharper than bouba, but is not.
It's more in terms of harmonic content than the pitch fundamental. There are more harmonics from a thing with sharp transitions than there are in a thing with rounded transitions regardless of the fundamental pitch. Compare harmonic content of a pure sine wave (it's just the fundamental) with that of a square wave, which has an infinite series of higher harmonics.
Babies are also smaller, which means higher fundamental pitch.
> "kiki" is not just higher pitched, it is also "shaped" differently if you look at the sound envelope, with, as expected, sharper transitions.
Exactly!
EDIT I think this is interesting: it also applies to images as well, not just sound. You can "low pass filter" a photograph and it'll reduce some of the detail, smoothing out transitions (typically used for noise reduction). Detail is high frequency information (or high frequency noise depending on whether you want it or not.)
Hens make it occasionally when laying eggs, but it's also the rooster alarm sound. The "cock-a-doodle-doo"/crowing sound is more the all-clear/I'm-a-rooster-here-I-am/flock-assemble cry.
When there's a threat, the rooster switches to a loud, BAWK BAWK BAWK alarm.
Formulating theories is all nice and dandy, but it ain't science.
Does the original paper (I couldn't find it in the article) explore this a bit more ?
It's actually nice if the effect can be studied on chickens, they are definitely less expensive and more plentiful than human babies.
Formulating theories ain't the whole of science, but it's a big part of it.
Thump a round club/log against a rock -> dull bump noise
Thump pointy branch against a tree -> dull noise
And chickens aren't using tools.
In your example it's obviously the round tree trunk that produces the dull sound.
And where did you get that from? In non-tonal languages the pitch conveys almost no information and people speak at very different ones (and for instance a male saying "kiki" will say it at lower frequencies than a woman saying "bouba" most of the time) so I find your affirmation very dubious.
> and it's no mystery why the brain associates one with the other.
Specialists of the field find that mysterious but some smartass on HN disagrees.
> And where did you get that from? In non-tonal languages the pitch conveys almost no information and people speak at very different ones (and for instance a male saying "kiki" will say it at lower frequencies than a woman saying "bouba" most of the time) so I find your affirmation very dubious.
You misunderstand the post. It has nothing to do with the voice of the speaker.
Long drawn-out sounds have lower frequency components than short-lasting sounds. A pin drop is REALLY high-pitched; a moan has at least some low-pitch components (but may still be high-pitched, too - more often called a "keening" than a moan). It's not about intonation; it's a mathematical consequence of the relationship between frequency and time-domain incidents, typically measured with Fourier transforms.
E.g. a spider does not learn if/how to weave a web from its parents.
all this research could be deeply flawed, however.