Analysis of information sources in references of the Wikipedia article "Tom de Shepard" in Portuguese language version.
It's like a barber's pole of sound.
The sound for which Risset is best known is perhaps the most emblematic of his contributions. Creating a sonic illusion much like M.C. Escher’s optical ones, the Shepherd-Risset glissando / Risset scale, in its present form invented by the French composer, seems to ascend forever.
It turns out I was thinking about a Shepard tone, the illusion of ever-ascending pitches
