[See Letters …HERE – Brian was asked if inspiration for the intro of “Tie Your Mother Down” and outro of “Teo Torriatte” was from an Escher’s drawing, using similar to “Shepard’s Scale” described on Wikipedia.]
Ha ! No ! I certainly had never come across this when I wrote TYMD. I suspect somebody has invented this term since I did the track, and kindly explained how I did it ! I’m pretty sure I invented the technique. And yes, it was inspired by the M. C. Escher illustration which shows eternally climbing flights of stairs around what looks like a small castle.
But what these people have not realised, apparently, is that you have to continually change the mix of the octaves as you move the note up or down, in order for the effect to work. You have to gradually fade out the high tones as you move up, and vice versa.
Also, the tones do not have to be pure sine waves – mine weren’t.
And to call the effect a ‘scale’ is inaccurate. You can’t call this effect “Shepherd’s Scale”, or anybody else’s !
It is not a scale … it is a technique – you could use any scale to show the effect …
I am always suspicious of Wikipedia. Be very careful of it. Because, of course, anybody can put stuff on there, without any qualification whatsoever. And they deliberately don’t include contributions from people doing original research – only people quoting them. That’s why most scientific journals do not accept references to Wikipedia in their papers.