158 research outputs found
MoReeSC: a framework for the simulation and analysis of sound production in reed and brass instruments
International audienceThis paper presents a free and open-source numerical framework for the simulation and the analysis of the sound production in reed and brass instruments. This tool is developed using the freely distributed Python language and libraries, making it available for acoustics student, engineers and researchers involved in musical acoustics. It relies on the modal expansion of the acoustic resonator (the bore of the instrument), the dynamics of the valve (the cane reed or the lips) and of the jet, to provide a compact continuous-time formulation of the sound production mechanism, modelling the bore as a series association of Helmholtz resonators. The computation of the self-sustained oscillations is controlled by time-varying parameters, including the mouth pressure and the player's embouchure, but the reed and acoustic resonator are also able to evolve during the simulation in order to allow the investigation of transient or non-stationary phenomena. Some examples are given (code is provided within the framework) to show the main features of this tool, such as the ability to handle bifurcations, like oscillation onset or change of regime, and to simulate musical effects
Modal analysis of the input impedance of wind instruments. Application to the sound synthesis of a clarinet
International audienceThis paper investigates the modal analysis of wind instruments as seen from the input of their air column. Beside the treatment of analytical models, a particular emphasis is given to the analysis of measured input impedances. This requires special care because the measurements cover only a limited frequency band and are affected by some unknown errors. This paper describes how the Prony analysis and the Least Squares Complex Exponential (LSCE) classical techniques can be used in this context and how the main pitfalls can be avoided in their application. A physically acceptable method of reconstruction of the low frequency band is proposed. A technique using fictitious points in the high frequency range is described in order to ensure the passivity of the resonator in the whole frequency band. The principles of a real-time synthesis of clarinet sounds based on the modal representation of the resonator is given as an application, with a method to efficiently handle the modal representation during the transition between fingerings
Energy conserving schemes for the simulation of musical instrument contact dynamics
Collisions are an innate part of the function of many musical instruments.
Due to the nonlinear nature of contact forces, special care has to be taken in
the construction of numerical schemes for simulation and sound synthesis.
Finite difference schemes and other time-stepping algorithms used for musical
instrument modelling purposes are normally arrived at by discretising a
Newtonian description of the system. However because impact forces are
non-analytic functions of the phase space variables, algorithm stability can
rarely be established this way. This paper presents a systematic approach to
deriving energy conserving schemes for frictionless impact modelling. The
proposed numerical formulations follow from discretising Hamilton's equations
of motion, generally leading to an implicit system of nonlinear equations that
can be solved with Newton's method. The approach is first outlined for point
mass collisions and then extended to distributed settings, such as vibrating
strings and beams colliding with rigid obstacles. Stability and other relevant
properties of the proposed approach are discussed and further demonstrated with
simulation examples. The methodology is exemplified through a case study on
tanpura string vibration, with the results confirming the main findings of
previous studies on the role of the bridge in sound generation with this type
of string instrument
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