I thank Peter Desain and Andrzej Duda who accepted to report on this work. I would like to thank Claude Girault, François Pachet, and Christian Queinnec who are willing to be members of the jury.

Special thanks must go to Gérard Assayag who accepted me in his team during more than three years. His ideas and vast musical culture enriched this work; his generosity and support have been exemplary.

I thank my supervisor Emmanuel Saint-James. Although we work in different places he closely followed my work. His comments and suggestions on this work have been invaluable.

I would like to thank the professors of the DEA ATIAM for accepting me to their classes. Thanks to Jean-Claude Risset and Philippe Depalle.

The fantastic team spirit has been a major stimulans for my work. Many thanks and coffees to Carlos Agon, Claudy Malherbe, Camilo Rueda, Olivier Delerue, and Benoit Meudic.

I thank Ircam and the many people that helped me there. Thanks to Hugues Vinet, Marie-Therese Join, Sylvie Benoit, Dominique Doublet, Laurent Ghys, Eric Daubresse, and Serge Lemouton.

I would like to thank Brad Garton (Columbia), Robert Rowe (NYU), and Daniel Oppenheim (IBM) for their hospitality and exchange of ideas during several trips to New-York.

The discussions with Marco Stroppa, Gerhard Eckel, Ramon González-Arroyo have been very enriching. Artistic projects of projects inspired my work. Thanks to Didier, Sylvie, Erik, Alain, Renny. Special thanks to Daniel and Sam for reformulating my thesis.

I would to like to thank the friends for bearing with me the last three years: Laurent ``Brain'', Bennet, Adrien, Franscisco, Federico, Geoffroy, Christophe, Richard, Tom, and Gilbert.

Finally, I would like to thank my parents. Without their support there would have been no expedition to Paris and no finished thesis.