[Groxx]

>Open the song Aerodynamic and fast-forward to 2:28, start listening to the passage. I hear the higher pitch on my right and the lower one on my left ear. What about you?

tbh I'm not sure which notes they're referring to here. There are a couple overlapping high/low pairs in that segment, and I'm not sure which is the octave/those frequencies.

One seems like higher is more in my left, but it clearly follows the left speaker on my headphones. The others warble around for me, though I'm pretty strongly right handed.

---

Even after reading and listening to https://en.wikipedia.org/wiki/Octave_illusion I'm totally lost as to what this post or wikipedia are describing. Are people hearing like:

    left ear        right ear
    -------------------------
    high                        (nothing in right ear)
                    low
    high       
                    low

or something else? I mostly hear:

    left ear       central       right ear
    --------------------------------------
    high           low           low
    low            low           high
    high           low           low
    low            low           high

I'm definitely hearing "low" while hearing "high" on the opposite ear, though it feels like there's a basically constant central "low" as well. The high tone clearly moves between sides.

Maybe worth mentioning: I've had a hearing test in the past year and I'm essentially completely balanced, so there likely isn't a tone-deafness issue on one side that could cause a reception imbalance. Could the illusion just be hearing damage? And then handedness just follows which ear takes more damage due to more noisy things happening / less protection on that side? That could also explain why left-handed people are less strongly sided, as they're forced to do things more balanced due to right-hand-only stuff existing.

[gizajob]

It's the Shepard tone effect running in the background of the actual notes, which produce a mild illusion that they're ascending when they're not, but nevertheless they're moving up and then down in pitches so it's not a brilliant example. I think the author is a little confused in this short essay about a few things. His "talking piano" effect is just standard vocoding, which has made me think this is all fairly new to him and he's not an expert.

THIS is a talking piano: https://youtu.be/muCPjK4nGY4

[squeaky-clean]

I'm pretty sure the blog author is referring to 2 hard panned synths, the sort of plucky one in the right and more smooth one on the left. There's also a 3rd more "nasal" synth voice in the center which is playing the same pattern with the high/low notes inverted except for the quicker 4 note run that happens on the 4th count of every bar, where it synchronizes again. I don't think it's octave effect, but it produces a similar result and all 3 synths seem to occupy their own separate frequency space while also sounding like one unit.

This article has a decent recreation of the left and right synths in Aerodynamic. It does not include the center sound though.

https://reverbmachine.com/blog/daft-punk-discovery-synth-sou...

There is no shephard tone running in the background, that's a phaser effect running over an otherwise plain pad playing chords.

You can hear from 2:52 to 2:55 it's descending and from 2:56 to 2:59 it's rising. Descending again at 3:00 to 3:03 and etc.

Here's a video of someone replicating that phaser fx tone very well. Though they use it in the guitar solo. Listen to the resonant sweep that seems to be in the background, it's a phaser on the guitar.

https://youtu.be/eN5LWM2b6co

[ugurnot]

The tone I'm referring to is the alternation between F#3 and F#4. I think your observation about the Shepard tone is valid. For the talking piano effect, I remember trying to play it on guitar to make it sound like "Robot Rock". I suspect this is in relation to Tethard's example of accentuation by spectral contrast, but that was a long shot to include.

Well, the audio area is full of masters and experts. I make no claim to be an expert, so you can ignore this writing as you prefer.

[Applejinx]

Yup. The Daft Punk 'Robot Rock' is a straight up vocoder (mind you, a cool effect!). I like your link, now that's a talking piano :)

[vaastav]

Is it tho? It's only understandable to me if I also read the subtitles. Otherwise it just sounds as random noise.

[ilyt]

Same for me, just hearing the high tone bouncing around

Here is better video for that illusion: https://www.youtube.com/watch?v=IMMsK9rjBWo

I've heard of an effect where brain synthesises lower tone from the higher harmonics, might that be reason why I hear the low tone in both ears at once?

[gabereiser]

people are hearing what you hear. It's the simultaneous tones, one low, one high, low in the left, high in the right. It's not that it's panning (one at a time), it's together (or within ms of each other when mixed with other techniques). Once you understand this, then the concept of just flipping it makes even more sense. Then get creative and flippity floppity the high/low left/right dance.

[Groxx]

That's what the sounds are actually doing though, so what would the illusion be?

[gabereiser]

the illusion is it's perceived as the "same" note/tone. It's not, and when you dig, you can tell it's not, but when you're casually listening, your brain here's a "fuller" note for some reason. The "fuller" comes from the two octaves being played simultaneously in your seperate ear holes.

Like sleight-of-hand, you know it's there but you can't quite discern it at the time and are gladly surprised by it but you know it's not real magic.

[Groxx]

This sounds like it might be conflating stuff like vibrato (human-fast variation in pitch) or even faster. The illusion in the post and on the Wikipedia page involves changing the tone only four times per second, there's no claims at all about both tones blending together or producing only a single note.

Both are quite clear about different ears hearing different things, and hearing two or more tones.

[gabereiser]

I’m referring to the perceived sounds. They aren’t blended together. I’m fully aware of what vibrato is and what the post is talking about in terms of changing tone, half tones, auditory phantoms, trichords, and the octave illusion. The Wikipedia page details the phenomenon with stepping and alternating but it’s not the end of it. Various intervals have been tested. Us musicians have been playing with this for a while now.

[Groxx]

This whole thread is about the octave illusion, which is a very specific subset of psychoacoustics, and AFAICT the post accurately summarizes it as:

>There is one octave between the tones. If the alternation is short enough, you will hear the higher tone in one ear and the lower in the other.

No changes. Handedness of sounds that already exist.

[ilyt]

I don't hear that. I hear constant low tone in both ears with only high one bouncing around (i.e the ear where high is is perceiving low one even if it is not there)

[Groxx]

With the Wikipedia sample, I kinda suspect the central low note is the same phenomenon as binaural beats - 400hz and 800hz constructively interfere to produce 400hz. There is no 400hz on the high side, but we perceive interference even though there is none.

Which means it should disappear or produce a third tone if it wasn't an exact doubling. I haven't hunted down a sample to test though.