Hochschule für Musik / Schola Cantorum Basiliensis
Dauerhafte URI für die Sammlunghttps://irf.fhnw.ch/handle/11654/51
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6 Ergebnisse
Ergebnisse nach Hochschule und Institut
Publikation Cartes itérées appliquées à un instrument de type clarinette(04/2010) Taillard, Pierre-André; Kergomard, Jean; Laloë, Franck; Karkar, SamiMc Intyre et coll. (1983) ont montré que l’on peut ramener le calcul des oscillations d’une clarinette à une simple itération, dans un modèle où le résonateur est cylindrique avec des pertes indépendantes de la fréquence, et où l’anche est vue comme un ressort sans inertie. Pour cela on choisit le couple des ondes aller et retour comme variables de base, et le système peut se ramener à l’itération d’une fonction f(x) qui relie les amplitudes de ces ondes, conduisant à des oscillations en signaux carrés. Nous donnons une étude plus approfondie de cette fonction et en déduisons un encadrement des valeurs des paramètres d’excitation pour lesquelles l’anche peut battre, ou encore pour lesquelles le signe du débit peut s’inverser. Les fonctions itérées de la fonction f(x) renseignent notamment sur la stabilité des régimes périodiques, ou aident à comprendre l’existence de régimes chaotiques, de fenêtres de périodicité ou d’intermittences.06 - PräsentationPublikation Statistical Estimation of Mechanical Parameters of Clarinet Reeds Using Experimental and Numerical Approaches(Hirzel, 2014) Taillard, Pierre-André; Gross, Michel; Dalmont, Jean-Pierre; Kergomard, Jean; Laloë, FranckA set of 55 clarinet reeds is observed by holography, collecting 2 series of measurements made under 2 different moisture contents, from which the resonance frequencies of the 15 first modes are deduced. A statistical analysis of the results reveals good correlations, but also significant differences between both series. Within a given series, flexural modes are not strongly correlated. A Principal Component Analysis (PCA) shows that the measurements of each series can be described with 3 factors capturing more than 90% of the variance: the first is linked with transverse modes, the second with flexural modes of high order and the third with the first flexural mode. A forth factor is necessary to take into account the individual sensitivity to moisture content. Numerical 3D simulations are conducted by Finite Element Method, based on a given reed shape and an orthotropic model. A sensitivity analysis revels that, besides the density, the theoretical frequencies depend mainly on 2 parameters: EL and GLT . An approximate analytical formula is proposed to calculate the resonance frequencies as a function of these 2 parameters. The discrepancy between the observed frequencies and those calculated with the analytical formula suggests that the elastic moduli of the measured reeds are frequency dependent. A viscoelastic model is then developed, whose parameters are computed as a linear combination from 4 orthogonal components, using a standard least squares fitting procedure and leading to an objective characterization of the material properties of the cane Arundo donax.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Iterated maps for clarinet-like systems(Springer, 2010) Taillard, Pierre-André; Kergomard, Jean; Laloë, FranckThe dynamical equations of clarinet-like systems are known to be reducible to a non-linear iterated map within reasonable approximations. This leads to time oscillations that are represented by square signals, analogous to the Raman regime for string instruments. In this article, we study in more detail the properties of the corresponding non-linear iterations, with emphasis on the geometrical constructions that can be used to classify the various solutions (for instance with or without reed beating) as well as on the periodicity windows that occur within the chaotic region. In particular, we find a regime where period tripling occurs and examine the conditions for intermittency. We also show that, while the direct observation of the iteration function does not reveal much on the oscillation regime of the instrument, the graph of the high order iterates directly gives visible information on the oscillation regime (characterization of the number of period doubligs, chaotic behaviour, etc.).01A - Beitrag in wissenschaftlicher ZeitschriftPublikation An Analytical Prediction of the Bifurcation Scheme of a Clarinet-Like Instrument: Effects of Resonator Losses(Hirzel, 2015) Taillard, Pierre-André; Kergomard, JeanThe understanding of the relationship between excitation parameters and oscillation regimes is a classical topic concerning bowed string instruments. The paper aims to study the case of reed woodwinds and attempts to find consequences on the ease of playing. In the minimum model of clarinet-like instruments, three parameters are considered: i) the mouth pressure, ii) the reed opening at rest, iii) the length of the resonator assumed to be cylindrical. Recently a supplementary parameter was added: the loss parameter of the resonator (using the “Raman model”, that considers resonator losses to be independent of frequency). This allowed explaining the extinction of sound when the mouth pressure becomes very large. The present paper presents an extension of the paper by Dalmont et al. (JASA, 2005), searching for a diagram of oscillation regimes with respect to the reed opening and the loss parameter. An alternative method is used, which allows easier generalization and simplifies the calculation. The emphasis is done on the emergence bifurcation: for very strong losses, it can be inverse, similarly to the extinction one for weak losses. The main part of the calculations are analytical, giving clear dependence of the parameters. An attempt to deduce musical consequences for the player is given.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Numerical Computation of the Transfer Functions of an Axisymmetric Duct with the Extended Discrete Singular Convolution Method(08.07.2014) Taillard, Pierre-André; Hélie, Thomas; Bensoam, JoëlThis work takes part of the "cagima" project (supported by the ANR) which investigates the defects of the tuning of reed musical instruments as well as their homogeneity of emission and timbre. The goal consists in replacing the traditional approach adopted by instrument makers by a global and rational approach in the design of new instruments /ab initio/ (called "logical instruments"), minimizing some identi ed defects. In this context, an interactive virtual model, predictive and con gurable is proposed. Several approaches are available in the literature but the main di culty is to design digital instruments that are accurate (according to measurements) and that can be implemented in real-time. In this paper, an approach based on the Extended Discrete Singular Convolution method (EDSC) is proposed. The temporal operator (including the fractional derivative term for viscothermal losses) is implemented according to the EDSC formalism. The method allows a fast, straightforward and accurate computation of the transfer functions of an axisymmetric duct with an arbitrary pro le. The computation of the case where the losses are dependent from the diameter causes no noticeable di culty. The results are compared to measurements of a trombone bell.06 - PräsentationPublikation Scraping technique for clarinet reeds derived from a static bending(26.04.2012) Taillard, Pierre-André; Dalmont, Jean-PierreReed scraping is an art mastered only by a few clarinettists. The published empirical methods do not agree on how to determine where to scrape. In order to understand the problematic more clearly, a purely mechanical and simplified approach is attempted. The reed is modelled by finite elements and a simulation of free static bending shows that the longitudinal flexural stress dominates the problem. By targeting a stress field on different areas of the reed, it is observed that the strain is mainly longitudinal and only slightly lateral, due to the strong anisotropy of the cane (Arundo donax). Thus, a bending moment imposed on the axis of the reed causes almost no translation of the edges of the reed. A local decrease in thickness causes a localized increase in curvature, when the stress field remains constant. With this result, a series of ClaripatchTM was developed to impose a localized decrease in curvature on the mouthpiece’s lay. Using these patches and assuming some hypotheses based on observations, simulations and on the viscoelastic properties of the reed, one can deduce how to scrape it, according to the musical preferences of the clarinettist.06 - Präsentation