Image:DescenteInfinie.ogg

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DescenteInfinie.ogg (Fichier son Ogg Vorbis, durée 1m6s, 42kbps)

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[edit] Summary

[edit] Comments

  • English : This is a Shepard-Risset glissando. I programmed this acoustic illusion in Java one year ago. Unfortunately, the source code is lost today because of a computer crash, but the equation is below.
  • Français : Ceci est un glissando de Shepard-Risset. J'ai programmé cette illusion acoustique en Java il y a un an. Le code source est malheureusement perdu (crash de mon ordinateur), mais l'équation est présentée ci-dessous.
  • Español : Este sonido es un Shepard-Risset glissando. Programe esta ilusion acustica hace un año en Java. Desafortunadamente, el codigo se perdio al estropearseme el ordenador pero la ecuacion esta abajo.

[edit] Equation

\,s T-periodic on \mathbb{R}

\forall t \in \left [0, T \right [

\,s(t) = a(t) \sin \left ( \omega(t) t \right ) + a(t + T) \sin \left (2 \omega(t) t \right )

with 
\begin{cases}
\begin{array}{lcl}
a(t) & = & A_0 \cfrac{1 + \cos \pi \frac{t}{T}}{4} \\
\omega(t) & = & 2 \pi F_0 \cfrac{1}{2^\frac{t}{T}} \\
F_0 & = & 220\,Hz \\
T & = & 20\,s \\
A_0 & = & 0.7
\end{array}
\end{cases}

The same signal is added on a minor chord, on several octaves, see details on my web site.

--Gloumouth1 01:39, 10 December 2005 (UTC)

[edit] Loop

If you want to have a loop, as T = 20 s, you can crop this sound exactly from 20 s to 40 s.

[edit] Another idea

If I (or you) have time, one day, another function which could be programmed and recorded...

\forall t \in \mathbb{R} \quad s (t) = \sum_{k=-\infty}^\infty a_k(t) \sin \left ( \omega_k(t) t \right )

with 
\begin{cases}
a_k(t)       =  A_0 e^{-\cfrac{ \left ( k-\frac{t}{T} \right ) ^2}{\sigma^2}} \\
\omega_k(t)  =  2 \pi F_0 2^{k - \frac{t}{T}} \\
A_0, F_0, T, \sigma \, constants
\end{cases}

--Gloumouth1 17:04, 5 March 2007 (UTC)

[edit] Licensing

This illustration was made by Gloumouth1.

Please credit this : Gloumouth1, http://gloumouth1.free.fr

An email to gloumouth1 at laposte.net would be appreciated too.

I, the copyright holder of this work, hereby publish it under the following licenses:
GNU head Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation license, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation license".

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This file is licensed under the Creative Commons Attribution ShareAlike 2.5 License. In short: you are free to share and make derivative works of the file under the conditions that you appropriately attribute it, and that you distribute it only under a license identical to this one. Official license
You may select the license of your choice.

josh

Historique du fichier

Cliquer sur une date et une heure pour voir le fichier tel qu’il était à ce moment-là

Date et heureDimensionsUtilisateurCommentaire
actuel9 décembre 2005 à 23:401m6s (336 Kio)Gloumouth1 (en:Shepard tone I programmed it in en:Java one year ago. --Gloumouth1 Category:Synthetic sound)

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