Workshop on Physical Sound Synthesis: Ness/STMS/LAM-IJLRA

The “NESS” team (Next Generation Sound Synthesis, ERC project) of the University of Edinburgh was in Paris the 13 and 14 october 2016 to present scientific and musical results of the project (Schedule).

S3 team presentations:

Summer school Science and Voice: expression, use and care of the human vocal instrument

26th to 30th september 2016, Porquerolles, France :

  • Course (Thomas Hélie and Fabrice Silva): Physique de la dynamique glottique : aspects énergétiques et auto-oscillations (in french: summary, slides)
  • Practical work (Thomas Hélie and Fabrice Silva): Acoustique du conduit vocal (in french: summary)

PhD defense: Antoine Falaize

Tuesday 12 july 2016, 2.30 pm – Ircam, salle Igor Stravinsky (

Antoine FALAIZE will defend his PhD work entitled:

“Modeling, Simulation, Code Generation and Correction of Multi-Physical Audio Systems: Approach by Network of Components and Port-Hamiltonian Formulation”



This work took place in the Project-Team Sound Signals and Systems and in the Analysis-Synthesis team of Laboratoire Sciences et Technologies de la Musique et du Son, IRCAM-CNRS-UPMC under the supervision of Thomas Hélie (Researcher, UMR STMS, IRCAM).

It is part of the ANR (French National Research Agency) project: ANR-HamecMopsSys.

This work will be defended to the following jury:

M. Stefan Bilbao           Rapporteur, Professeur, Acoustics and Audio Group, Edinburgh University

M. Pierre Rouchon       Rapporteur, Professeur, Centre Automatique et Systèmes, Mines-ParisTech

M. Benoît Fabre            Examinateur, Professeur, Équipe Lutherie Acoustique Musique, IJLRA, Université Paris 6

M. Yann Le Gorrec       Examinateur, Professeur, École Nationale Supérieure de Mécanique et des Microtechniques, FEMTO-ST/AS2M

M. Aziz Hamdouni       Examinateur, Professeur, Laboratoire des Sciences de l’Ingénieur pour l’Environnement, Université de La Rochelle

M. Hervé Lissek            Examinateur, Professeur, LTS2, École Polytechnique Fédérale de Lausanne

The class of audio systems includes traditional musical instruments (percussion, string, wind, brass, voice) and electro-acoustic systems (guitar amplifiers, analog audio processing, synthesizers). These multi-physical systems have a common property: out of excitation sources (generators), they are all passive. We present a set of automatic methods dedicated to their modeling, simulation and control, which explicitly guarantee and exploit the passivity of the original system. This class of systems is that of port-Hamiltonian systems (PHS), introduced in system theory in the early 1990s.
Regarding the models, we exploit the fact that the interconnection of systems described in this formalism explicitly preserves the dynamics of total dissipated power. This enabled the development of an automated method that builds models of complete instruments based on a dictionary of elementary models.
Regarding the simulations, we developed a numerical method that preserves the passive structure of PHS in discrete-time domain. This ensures the stability of simulations (for which the C++ code is automatically generated).
Regarding the control, we exploit the interconnection structure to automatically build an input-to-output decoupled form for a class of PHS. Systems of this class are flat, within the meaning of the differential flatness approach. A formula that yields the (open loop) control law for these systems is provided.

PhD defense: Nicolas Lopes

Wednesday 15 june 2016, 2.30pm – Ircam, salle Igor Stravinsky (

Nicolas LOPES, will defend his PhD work entitled:

Passive approach for the modelling, the simulation and the study of a robotised test bench for brass instruments.”Photo Robot

This work took place in the Project-Team Sound Signals and Systems and in the Analysis-Synthesis et Instrumental acoustics teams of Laboratoire Sciences et Technologies de la Musique et du Son, IRCAM-CNRS-UPMC.

It is part of two ANR (French National Research Agency) projects: ANR-HamecMopsSys and ANR-Cagima.

This work will be defended to the following jury:
Brigitte d’Andréa-Novel   Rapporteur – Professeur Mines-ParisTech

Christophe Vergez            Rapporteur – Directeur de Recherche, CNRS LMA

Benoît Fabre                      Examinateur – Professeur, LAM, Institut d’Alembert, UPMC

Isabelle Terrasse               Examinateur – Directrice de Recherche, Airbus Group Innovations

Bernhard Maschke           Examinateur – Professeur Université Claude Bernard, Lyon 1

Thomas Hélie                    Directeur de thèse – Chargé de Recherche, Laboratoire STMS, CNRS

René Caussé                      Co-directeur de thèse – Directeur de Recherche, Laboratoire STMS, Ircam



This thesis is to be seen against the robotic, the automatic, and the musical acoustics backgrounds.

It provides a study of a robotised test bench for brass instruments. This study is divided into three parts: the passive modelling of the system, its simulation and its development. The modelling is done using a passive formalism, namely, the ports-Hamiltonian systems. The main parts of the complete system are: an air supply for the breath, an acoustic exciter itself composed of a couple of artificial lip and an air jet, and an acoustic resonator. In this work, the acoustic resonator is a valve trombone. A new model for the air jet generated between the lips is proposed. This model aims at providing a power balance, which is closer to the real system than other commonly used models. Refinements are added to the jet model to obtain a self-oscillating complete model. The discrete gradient method is presented to perform simulations. This method offers a discrete time description that verifies the power balance, and then the passivity during simulations. However, it does not generally guaranty the existence and uniqueness of a solution. Moreover, it is limited to the second order of numerical consistency, and its execution needs nonlinear optimisation algorithms, that are time-consuming processes. To compensate for these limitations, a multi-stage method of double Runge-Kutta type and based on a change of variable is proposed. Results from simulations are interpreted and compared to those coming from a Bernoulli type model. Finally, the test bench and the technical developments carried out in this thesis are presented. These developments are both about programming and mechanic. They enable the performance of repeatable cartographies experiments which can be used to characterise music instruments. Experimental and numerical results are compared. Comparisons enable the highlighting of the defaults and the qualities of the proposed model and lead to future choices for the modelling and the development of the test bench.

Invited seminar: Thomas Hélie, Outils scientifiques et technologiques pour les systèmes et signaux sonores (Tuesday 16th february 2016, Team “Recherche opérationnelle et mathématiques appliquées”, ISAE, Sup’aéro, Toulouse)

In this seminar, I will present a few scientific and technological tools we develop to model physical systems and process the resulting sound signals. The introduction gives a brief scan of the S3 team activities, physical modeling, nonlinear systems, robotics and analysis / sound synthesis. A more thorough presentation on Port Hamiltonian Systems (HamecMopSys project), the development of a class of non-linear damping and guaranteed passive simulation will be given and illustrated in the case of bars sound synthesis.
We will provide sound examples for materials whose properties mutate (wood to metal, for example) with the signal amplitude (metallophone to marimba, for example), producing “physically sensible sound morphing” effect. Finally, I will conclude with a presentation of a frequency analysis tool of the sound signal and visualization: the SnailAnalyser-Tuner (The Snail). This tool provides an intuitive representation of sounds with chromatic alignment of the spectral components. Samples and demonstrations will be given during the presentation.



Invited seminar: Thomas Hélie, New tools for modelling musical systems and exploring musical sound (Wednesday 20th january 2016, TBC, Informatics Forum, University of Edinburgh)

In this presentation, I will present a few scientific and technological tools that we develop to model physical systems and to process sound signals. The introduction will be devoted to a short description of some activities of the Project-Team S3 in physical modelling, nonlinear systems, robotics, sound synthesis and sound analysis. Then, selected works will be deepened.

  • Port-Hamiltonian systems: sound synthesis based on the guaranteed-passive simulation of physical models.
  • Fractional filters: modelling and simulation of a class of low-pass filters, the slope of which can be continuously tuned from 0 (unit gain) to -6 decibel per octave (1 pole filter).
  • SnailAnalyser: a frequency-domain analyser that delivers in real-time an intuitive representation of sounds based on the chromatic alignment of spectral active zones.

Sound examples and demonstrations will be given along this presentation:

  • Port-Hamiltonian systems:

Sound slide 19

Sound slide 20

  • SnailAnalyser:

SnailAnalyser Demo

Invited seminar: Antoine Falaize, Passive structure for modelling, simulation and control of audio multiphysics systems (10 december 2015, LaSIE, Université de La Rochelle)


Presentation (in french)

Control techniques in vibrations, acoustics and music

On November 16th 2015 TCVAM day was held at IRCAM with the support of the French Acoustics Society (SFA) and organised by Thomas Hélie of the Musical Acoustics working group (GSAM) and Kerem Ege of the Noise and Vibration control working group (GVB).





Collegium Musicae

S3 team presentation has been made at the inaugural seminar of the Collegium Musicae at the Philarmonie de Paris on November 13th.

Presentation (ppt in french)

Presentation video (with speech in french)