Re: Shepard tone

[Daryl Shawn <highhorse@mhorse.com>]

Per, thanks for this, I missed this on the Wiki page. I'm working it out 
on guitar, but am not convinced it really creates the same illusion, 
possibly because there are only so many octaves to work with. In the 
example below, do you have any idea if the instruments are spread so far 
apart that no instrument ever crosses into the other's octave? I'm going 
to try to record my version this weekend.

and Qua, thanks for the Exploratium link. I visited the museum a number 
of years ago and vaguely remember the round keyboards...super cool.

Daryl Shawn
www.swanwelder.com
www.chinapaintingmusic.com
>> Very interesting! At http://en.wikipedia.org/wiki/Shepard_tone I found
>>> consider a brass trio consisting of a trumpet, a horn, and a tuba. 
>>> They all start to play a repeating C scale (C-D-E-F-G-A-B-C) in 
>>> their respective ranges, i.e. they all start playing C's, but their 
>>> notes are all in different octaves. When they reach the G of the 
>>> scale, the trumpet drops down an octave, but the horn and tuba 
>>> continue climbing. They're all still playing the same pitch class, 
>>> but at different octaves. When they reach the B, the horn similarly 
>>> drops down an octave, but the trumpet and tuba continue to climb, 
>>> and when they get to what would be the second D of the scale, the 
>>> tuba drops down to repeat the last seven notes of the scale. So no 
>>> instrument ever exceeds an octave range, and essentially keeps 
>>> playing the exact same seven notes over and over again. But because 
>>> two of the instruments are always "covering" the one that drops down 
>>> an octave, it seems that the scale never stops rising.