Physical modeling of the piano
This page is devoted to my contributions to piano modeling. This instrument is an interesting case study from a modeling point of view, as the player has very limited contact with the vibratory and acoustic part of the instrument, due to the key escapement mechanism. Indeed, after a key is depressed, the corresponding hammer head is propelled by a push on the neck from the escapement stick, which very quickly loses contact with it. It is through these “throwing” gestures that pianists control their sound, reducing human action to the fine-tuning of a few initial conditions in the mechanical and vibratory model we can write. Of course, musicality derives from multiple parameters such as the dynamics of each note (piano/ forte), the arrangement in time of the different notes played (duration, articulation), the use of pedals that modify the vibratory properties of the instrument, the action of dampers, etc. From a scientific point of view, the approach consists of isolating each effect and trying to identify its consequences, by demonstrating one or more possible mechanisms, which are then modelled using mathematical models and their digital simulation. The multiphysical and highly coupled nature of the resulting system in itself raises mathematical and numerical difficulties. In particular, we have carefully considered the quasi-linear behavior of strings, and the impact of this behavior on sound, while keeping a formalism that guarantees a global energy identity that we hope will ensure the stability and convergence of the methods, in the presence of couplings. I had provided an initial modeling and simulation tool during my PhD thesis in 2012, we crudely modeled piano touch with Marc Duruflé in 2014, and we perfected several aspects during Guillaume Castera’s thesis, which I co-directed with Paul Fisette.