[Smt-talk] accellerandi-pieces

Robert Morris mris at mail.rochester.edu
Thu Oct 15 08:38:03 PDT 2009

Hi Justin,

In Jean Claude Risset's Mutations (an early computer music piece cira
1970) there is a temporal interpretation of the Shepherd tone idea that I
think works, so that one hears things (loudness pulsations)  getting
faster all the time, but also returning to the old tempo accelerando

Best, Bob

Robert Morris, Professor of Composition
Chair of the Composition Department
Affiliate Faculty of the Theory and Musicology Departments
Eastman School of Music, University of Rochester
phone: 585-274-1108.  e-mail: mris at mail.rochester.edu

On Thu, 15 Oct 2009, Justin London wrote:

> 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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