Supervision: Hervé Lissek,Etienne Rivet,Romain Boulandet

Project type: Master thesis


Electroacoustic resonators are devices comprising (at least) one electrodynamic loudspeaker and an electronic instrumentation (feedback based on pressure/velocity sensing, shunt with a synthetic electrical load). This control allows to significantly modify the acoustic impedance presented by the moving part (namely the membrane) of the loudspeaker, eg. by increasing/lowering the mechanical resistance, or by reducing the effective mass and stiffness, leading in interesting properties in terms of acoustic waves reflection. The usual applications are mainly sound absorption at low frequencies (“electroacoustic absorbers”), either in ducts or in room.

We aim at investigating the application of this technique to wind instruments control, in particular to develop a prototype of active mute. The main interest of the active mute is to mute the sound without altering the intonation. Indeed, the control of the acoustic impedance at the duct termination colours the instrument's sound, as the timbre results from the natural harmonic series of the instrument due to the boundary conditions. A second interest in the active mute is that it might facilitate the playability of the instrument, the emission being potentially made difficult by the obstructing object.

A former work led to the development of a numerical model of a trombone, with a passive mute, with an active control architecture (shunt impedance) inside the mute. Preliminary simulation show that the concept of acoustic impedance synthesis may be suitable to alter the resonances of the instruments, and may be implemented in a real sourdine.

The proposed work is to design and further optimize the active mute concept based on the electroacoustic resonator principle, following electroacoustic specifications (loudspeaker, acoustic enclosure) to be indentified. Then a prototype will be built and tested in laboratory conditions.

Profile: Electrical engineering, Micro-engineering, Physics, Mechanics

Prerequisites: Electroacoustique (BA5) or Audio Engineering (MA1)

Context: Theory (20%), design (60%), experiments (20%)