Less than four hours later, here we are, back with more polytonal "Heart and Soul." I knew that once I'd thought of recording this using the "Shepard tone" principle, there'd be no turning back. However, I let the little pianist inside my computer play all the notes this time and then, as I once did with Bach's modulating canon, the recording was layered so that as the upper octave of melody is fading out, a new lower octave is fading in. (There's also always a more stable middle octave.) The result: after the tune has finished rising step-by-stop into all twelve keys (always above an unchanging 50's progression in C Major), we're back where we started. It helps that one commonly hears people play this with the melody doubled in octaves anyway, so the shifting isn't as noticable as it might be in other contexts.
I have bigger plans still, but I'll go ahead and post this as part 2 of an ongoing series. Listen here or just download from here.