Bird song sonographs show distinct drawing patterns

You may be misunderstanding, though your username is very appropriate. :)

"Harmonics" here isn't referring to the harmonic complexity of songs.

It's referring to harmonics as in overtones, the complexity of the overtones -- the timbre.

It's the voice of the bird, not the songs it sings.

Harmonically complex is unrelated (unless they do something like Tuvan throat singing), but the species thing is a good point.

Compare a parrot or a crow vocalizing. From that it seems some can control the amount of overtone or at least can use two different modes or something.

Seems almost like comparing humans whistling vs speaking or something (assuming whistling is closer to a pure sine tone).

seems like selection bias, plenty of birds have both simple tone songs and harmonically complex vocalizations, if you just draw images from the first sample you will get nice single tone pictures

When a bird sings to attract a mating partner, competing against other birds, does it not sing for aesthetics?

Also, couldn’t harmonics be used to improve decoding in noisy environments? Spreading the signal over a wide band is not unheard of in man-made electromagnetic communication either.

I just had two thought considering this:

1. Do we appreciate bird songs because they indicate a resource rich/hospitable environment?

2. Do birds hear the entire range of the song, or just pick up specific bands?

I think the explanation is even simpler.

For a loud, high-pitched sound produced from a tiny object like a bird, is it even physically possible to have the loud resonances needed for overtones and timbre? I think it's just physics.

Whales are "signaling" over huge distances too but have plenty of overtones, since that's what low frequencies in huge cavities produce.

I'm not sure the dichotomy between "aesthetics" and "signaling" you suggest actually exists. A peacock's plumage is certainly aesthetics but also certainly signaling. And what is a birdsong's melody if not aesthetics?

Audio person here. I found the post fascinating, but I wish they did more to explain what they were talking about to a layperson.

Basically, all sounds that you hear are composed of many layered sine waves of different frequencies and intensities. The graphs in the post are spectrograms, which graph those frequencies over time. The Y axis represents pitch, the X axis represents time, and the brightness at any given point represents how loud that particular frequency was at that particular time.

Most sounds, even seemingly simple ones, look very complex on a sonogram, like a smudged pen stroke. The images of different instruments below demonstrate this; these are all very complex sounds, even though we only hear it as a single note being played. The voice one is one of my favorites, because it shows just how weird and complicated everyday sounds can get.

But bird songs are different; on a sonogram, they appear as a single line. The complexity of the bird songs here comes from the fact that they're taking a single sine wave and changing the pitch over time. Where most sounds look like a complex mix of smudged paint strokes, bird songs look like a single, precise, bouncing stroke.

Andrew Huang does a good job of explaining harmonics and overtones[0]. You only need to watch until about the 4 minute mark (from the timestamp) to get an explanation of harmonics and what the sonograms represent.

The short of it is that most natural sounds product a root tone plus a varying amount of related tones above it. Our ears hear the root tone, and the other tones above it are what give the sound its uniqueness. That's why a guitar, a clarinet and 3 singers can produce the same note while sounding distinct.

Birds seem to produce a natural sound without a lot of the related tones above it. Their sound is, relatively speaking, much purer than most other natural sounds. That's very unique.

[0]: https://youtu.be/Wx_kugSemfY?t=95

Interesting train of thought.

Perhaps it's good to know that the x axis (from left to right) is temporal. So for someone/something to translate this to an image with some special sense would also necessitate some memory part.

With a big fantasy you could continue your hypothesis by comparing it to describing an object you see with words by telling the height of the outline from left to right.

What if groups/species of birds had "collective synesthesia"?

Some people see colors or feel tastes... and it doesn't seem that unlikely that there would be selection pressure for parts of the bird brain to connect their spatial awareness to their auditory system and then songs. There could be a nice feedback loop that their own songs would strike similar experiences for themselves (if they hear themselves similar to others).

Of course we know that bats have this type of neural connection in echolocation and dolphins/whales may even using it to communicate in similar ways with their songs.

I heard a crazy theory that this is how dolphins communicate. As they perceive using sound and are able to produce sound, perhaps they project the sound of the thing they want to talk about. It would be the same as a human being able to shine any image we like onto a wall to communicate. Can they recreate the echo of a fish with high enough fidelity that it's recognisable to another dolphin?

Ups, I though if some dup is detected I would be warned before submitting. Will remove it.

Thanks!

Edit: Seems I can not remove it by myself :-(

This is my laymans test for the FFT theory.

Put in earbuds or a headset and (quietly) play sounds that are slightly different in frequency (1-10hz).

You will still hear a sort of ethereal beat tone between them that's different than the beat you would hear if you were listening to the same through speakers. I don't see how this would occur frequency-domain perception and it's too present (at least in my experiment) to be attributed to bone conduction across the skull.

I don't believe that's correct.

The hair cells in our inner ear are activated in response to specific frequencies, virtually identical to how an FFT operates.

There is then further processing attached to that, in the same way that we perceive colors rather than cones directly in our vision. With audio, we need to collapse entire series of overtones into a fundamental frequency with a timbre (color).

And specifically in the experiment linked, it's showing how the ear intelligently restores the missing fundamental.

But I don't believe there's any biological/neurological evidence to support that the ear detects periodic repetitions of an overall waveform, and that this explains the missing fundamental. To the contrary, how our hearing works biologically suggests that we are indeed performing something like FFT, but then applying sophisticated pattern recognition on it -- on the "FFT", not on the waveform.

That’s really cool! trying it out now. thanks for the recommendation.