[Smt-talk] accellerandi-pieces

[Justin London]

This is a nifty idea, but I don't think it works.  For the  
periodicities one tracks in the ritardando illusion are invidividual,  
discernable strands of the musical texture (so to speak), as these  
stream separately from the other periodicities at different rates in  
different registers.  Whereas in the case of the shepherd tones, the  
components tend to fuse into a single tone percept, which enables the  
illusion.

Best,
Justin London

On Oct 15, 2009, at 1:42 AM, Thomas Noll wrote:

Dear colleages,
with students in theory class we have been working on the idea of an  
infinite accellerando (or ritardando) in analogy to the illusion of  
infinite ascend (or descend) in pitch height in the Shepard scale (or  
glissando). The solution we came up with is a combination of
(1) a non-periodic self-similar rhythm (such as investigated by Norman  
Carey and David Clampitt in their 1996 PNM article: "Self-similar  
pitch structures, their duals, and rhythmic analogues"), which is  
played simultaneously at several speeds, where "old" levels fade out  
and new levels fade in through a Gaussian envelope for the amplitude,  
and
(2) an exponential time flow (which is the physical time of  
performance as a function of symbolic score time). All of the  
(infinitely many) voices silently start simultaenously at minus  
infinity  ;-)
One of the students, Christobal Massis Valencia (percussionist),  
realized a ritardando (in combination with an "infinite" descend) as a  
homework on that class:
http://user.cs.tu-berlin.de/~noll/sqrt2
Thomas Noll


*********************************************************
Thomas Noll
http://flp.cs.tu-berlin.de/~noll
noll at cs.tu-berlin.de
Escola Superior de Musica de Catalunya, Barcelona
Departament de Teoria i Composició

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*************************************************
Justin London, Professor of Music (and other stuff)
President, Society for Music Theory
Carleton College
Department of Music
One North College St.
Northfield, MN 55057 USA
507-222-4397
fax 507-222-5561
jlondon at carleton.edu




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