A detailed and helpful explanation, Gilberto – thanks so much. The professor's overly simplified comments on the emergence of sidebands described in terms of our brain tricking us was perhaps not the ideal way to convey the idea. He almost certainly did not mean it to be interpreted quite the way it came across to me, but provided ample opportunity for it. You know, I was certain as well that the sidebands would be evident in a spectrogram, clearly visible and measurable.
And contrary to his explanation that audible sidebands begin to emerge above low freq. oscillations of 20 cycles per sec, I very clearly hear them as low as 15, maybe 13 cycles per sec when oscillating a 170Hz sine wave. At 15 cycles, one distinctly perceives a major 3rd above the fundamental. But I'm curious, what change would I need to make to the patch in order to have the tone rather than oscillate, switch on and off, hard, from 0 amplitude to full on? Would the sidebands sound the same?
The patches are a good starting point on my end. It seems something like the "binaural beats" phenomenon can be recreated here – but in this basic Pd patch, this is not aurally 3-dimensional (how complex would adding dimensionality be? Quite, I'd imagine).
Perhaps this is what you're demonstrating already, but can the spectrogram here be compartmentalized into revealing, in separate spectrograms, the fundamental in one, and the sidebands in another? Are sidebands another form of harmonics or distinct and separate?