File:DescenteInfinie.ogg

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DescriptionDescenteInfinie.ogg	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. Español: Este sonido es un Shepard-Risset glissando. Programé esta ilusión acústica hace un año en Java. Desafortunadamente, el código se perdió al estropeárseme el ordenador pero la ecuación está abajo. 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.
Date	9 December 2005, 21:40
Source	Own work
Author	This illustration was made by Gloumouth1. Please credit this: Gloumouth1, Creative Commons Attribution-Share Alike An email to gloumouth1 at gmail.com would be appreciated too. I, the copyright holder of this work, hereby publish it under the following licenses: 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.http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. You are free: to share – to copy, distribute and transmit the work to remix – to adapt the work Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original. This licensing tag was added to this file as part of the GFDL licensing update.http://creativecommons.org/licenses/by-sa/3.0/CC BY-SA 3.0Creative Commons Attribution-Share Alike 3.0truetrue This file is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic license. You are free: to share – to copy, distribute and transmit the work to remix – to adapt the work Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original. https://creativecommons.org/licenses/by-sa/2.5CC BY-SA 2.5 Creative Commons Attribution-Share Alike 2.5 truetrue You may select the license of your choice.

Wikipedia  This is a featured sound on the English language Wikipedia (Featured sounds) and is considered one of the finest sound files. See its nomination here. If you think this file should be featured on Wikimedia Commons as well, feel free to nominate it. If you have an image of similar quality that can be published under a suitable copyright license, be sure to upload it, tag it, and nominate it.

${\displaystyle \,s}$ T-periodicon${\displaystyle \mathbb {R} }$

${\displaystyle \forall t\in \left[0,T\right]}$

${\displaystyle \,s($t)=a(t)\sin \left(\omega (t)t\right)+a(t+T)\sin \left(2\omega (t)t\right)}

with ${\displaystyle {\begin{cases}{\begin{array}{lcl}a($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\,{\text{Hz}}\\T&=&20\,{\text{s}}\\A_{0}&=&0.7\end{array}}\end{cases}}}

The same signal is added on a minor chord, on several octaves.

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

If you want to have a loop, as T = 20 s, you can crop this sound exactly from 18 s to 38 s.

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

${\displaystyle \forall t\in \mathbb {R} \quad s($t)=\sum _{k=-\infty }^{\infty }a_{k}(t)\sin \left(\omega _{k}(t)t\right)}

with ${\displaystyle {\begin{cases}a_{k}($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 \,{\text{constants}}\end{cases}}}

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

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