title: Idealized digital models for conical reed instruments, with focus on the internal pressure waveform.
abstract: Two models for the generation of self-oscillations of reed conical woodwinds are presented. The models use the fewest parameters (of either the resonator or the exciter), whose influence can be quickly explored. The formulation extends iterated maps obtained for lossless cylindrical pipes without reed dynamics. It uses spherical wave variables in idealized resonators, with one parameter more than for cylinders: the missing length of the cone. The mouthpiece volume equals that of the missing part of the cone, and is implemented as either a cylindrical pipe (first model) or a lumped element (second model). Only the first model adds a length parameter for the mouthpiece and leads to the solving of an implicit equation. For the second model, any shape of nonlinear characteristic can be directly considered. The complex characteristic impedance for spherical waves requires sampling times smaller than a round trip in the resonator. The convergence of the two models is shown when the length of the cylindrical mouthpiece tends to zero. The waveform is in semi-quantitative agreement with experiment. It is concluded that the oscillations of the positive episode of the mouthpiece pressure are related to the length of the missing part, not to the reed dynamics.
authors.affiliation: Laboratoire de Mécanique et d'Acoustique (LMA, Research Unit of CNRS 7051) Aix-Marseille University, Centrale Marseille, F-13453 Marseille Cedex 13, France.
authors.forename: J
authors.initials: J
authors.lastname: Kergomard
authors.affiliation: Laboratoire de Mécanique et d'Acoustique (LMA, Research Unit of CNRS 7051) Aix-Marseille University, Centrale Marseille, F-13453 Marseille Cedex 13, France.
authors.forename: P
authors.initials: P
authors.lastname: Guillemain
authors.affiliation: Laboratoire de Mécanique et d'Acoustique (LMA, Research Unit of CNRS 7051) Aix-Marseille University, Centrale Marseille, F-13453 Marseille Cedex 13, France.
authors.forename: F
authors.initials: F
authors.lastname: Silva
authors.affiliation: Laboratory of Electromagnetics and Acoustics, École Polytechnique Fédérale de Lausanne, Station 11 Route Cantonale, CH-1015 Lausanne, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Karkar