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