Ce travail présente une étude originale de l'interaction laser-matière en régime nanoseconde à l'aide d'une double approche expériences-modélisation numérique. L'approche expérimentale vise à caractériser les plasmas produits par laser et l'empreinte laissée par le faisceau laser sur la cible. L'approche numérique s'appuie sur un modèle 1D qui permet de décrire le chauffage de la cible par le laser, l'ablation de matière et la formation d'un plasma dans cette matière ablatée dûe à l'interaction avec le laser. Des comparaisons des résultats obtenus par les deux approches permettent d'évaluer le degré de précision des résultats issus du modèle. Ces comparaisons se limitent aux 100 premières nanosecondes d'expansion du plasma. Nous montrons ainsi que le modèle décrit assez bien l'écrantage du faisceau laser par le plasma, l'expansion du plasma et la propagation de l'onde de choc dans le gaz ambiant. De plus, les valeurs des seuils d'ablation et de formation du plasma sont calculées avec une bonne précision. En revanche, des écarts sont constatés pour la modélisation des processus d'interaction entre le laser et la cible. Le degré de précision du modèle est au final suffisamment bon pour nous permettre d'étudier précisément l'effet du gaz ambiant sur les propriétés et la dynamique du plasma. / This work provides an original study about laser-matter interaction in the nanosecond regime, based on a coupling between the experiments and the modelling. The experimental study provides a description of the dynamics of the laser produced plasmas. The modelling, based on a 1D numerical scheme, is aimed to describe the heating of the target by the laser pulse, the process of matter ablation and the formation of a plasma in this ablated material due to the interaction with the laser. The comparisons between both experimental and numerical results give the order of accuracy of the results obtained by modelling. These comparisons are limited to the first hundred nanoseconds of plasma expansion. We show that the plasma shielding, the plasma expansion and the propagation of the shockwave are well modelled. Furthermore, the values of both ablation and plasma formation threshold are accurately computed. However, many differences are observed in the results concerning the laser-target interaction process. Finally, the degree of accuracy of the model is sufficiently high to study precisely the background gas effet on both plasma dynamics and properties.

The bassoon is a conical woodwind instrument blown with a double-reed mouthpiece. The sound is generated by the periodic oscillation of the mouthpiece which excites the air column. The fundamental frequency of this oscillation is determined to a large extent by the resonances of the air column. These can be varied by opening or closing tone-holes. For any given tone hole setting a fine-tuning in pitch is necessary during playing. Musicians adjust the slit opening of the double-reed by pressing their lips against the opposing reed blades. These so-called embouchure corrections are required to tune the pitch, loudness and sound color of single notes. They may be tedious, especially if successive notes require inverse corrections. However, such corrections are essential: Due to the very high frequency sensitivity of the human ear playing in tune is the paramount requirement when playing music. This implies, that embouchure actions provide an important insight into a subjective quality assessment of reed wind instruments from the viewpoint of the musician: An instrument requiring only small corrections will be comfortable to play. Theoretical investigations of the whole system of resonator, reed, and musician by use of a physical model nowadays still seem insufficient with respect to the required precision. Therefore the path of well-described artificial mouth measurements has been chosen here. For the separate treatment of the resonator and the double-reed, existing classical models have been used. Modifications to these models are suggested and verified experimentally. The influence of the musician is incorporated by the lip force-dependent initial reed slit height. For this investigation a measurement setup has been built that allows precise adjustment of lip force during playing. With measurements of the artificial mouth parameters blowing pressure, mouthpiece pressure, volume-flow rate and axial lip position on reed, the experiment is fully described for a given resonator setting represented by an input impedance curve. By use of the suggested empirical model the adjustment parameters can be turned into model parameters. A large data set from blowing experiments covering the full tonal and dynamical range on five modern German bassoons of different make is given and interpreted. The experimental data presented with this work can be a basis for extending the knowledge and understanding of the interaction of instrument, mouthpiece and player. On the one hand, they provide an objective insight into tuning aspects of the studied bassoons. On the other hand the experiments define working points of the coupled system by means of quasi-static model parameters. These may be useful to validate dynamical physical models in further studies. The experimental data provide an important prerequisite for scientific proposals of optimizations of the bassoon and other reed wind instruments. It can further serve as a fundament for the interdisciplinary communication between musicians, musical instrument makers and scientists.

The bassoon is a conical woodwind instrument blown with a double-reed mouthpiece. The sound is generated by the periodic oscillation of the mouthpiece which excites the air column. The fundamental frequency of this oscillation is determined to a large extent by the resonances of the air column. These can be varied by opening or closing tone-holes. For any given tone hole setting a fine-tuning in pitch is necessary during playing. Musicians adjust the slit opening of the double-reed by pressing their lips against the opposing reed blades. These so-called embouchure corrections are required to tune the pitch, loudness and sound color of single notes. They may be tedious, especially if successive notes require inverse corrections. However, such corrections are essential: Due to the very high frequency sensitivity of the human ear playing in tune is the paramount requirement when playing music. This implies, that embouchure actions provide an important insight into a subjective quality assessment of reed wind instruments from the viewpoint of the musician: An instrument requiring only small corrections will be comfortable to play. Theoretical investigations of the whole system of resonator, reed, and musician by use of a physical model nowadays still seem insufficient with respect to the required precision. Therefore the path of well-described artificial mouth measurements has been chosen here. For the separate treatment of the resonator and the double-reed, existing classical models have been used. Modifications to these models are suggested and verified experimentally. The influence of the musician is incorporated by the lip force-dependent initial reed slit height. For this investigation a measurement setup has been built that allows precise adjustment of lip force during playing. With measurements of the artificial mouth parameters blowing pressure, mouthpiece pressure, volume-flow rate and axial lip position on reed, the experiment is fully described for a given resonator setting represented by an input impedance curve. By use of the suggested empirical model the adjustment parameters can be turned into model parameters. A large data set from blowing experiments covering the full tonal and dynamical range on five modern German bassoons of different make is given and interpreted. The experimental data presented with this work can be a basis for extending the knowledge and understanding of the interaction of instrument, mouthpiece and player. On the one hand, they provide an objective insight into tuning aspects of the studied bassoons. On the other hand the experiments define working points of the coupled system by means of quasi-static model parameters. These may be useful to validate dynamical physical models in further studies. The experimental data provide an important prerequisite for scientific proposals of optimizations of the bassoon and other reed wind instruments. It can further serve as a fundament for the interdisciplinary communication between musicians, musical instrument makers and scientists.:1 Introduction 1 1.1 Motivation 1 1.2 Scientific Approaches to Woodwind Musical Instruments 3 1.3 Organization of the Thesis 6 2 Acoustical Properties of the Bassoon Air Column 7 2.1 Wave propagation in tubes 7 2.1.1 Theory 7 2.1.2 Transmission Line Modeling 8 2.1.3 Implementation 18 2.1.4 Remarks on Modeling Wall Losses in a Conical Waveguide 19 2.2 Input Impedance Measurement 23 2.2.1 Principle 23 2.2.2 Device 23 2.2.3 Calibration and Correction 24 2.3 Comparison of Theory and Experiment 27 2.3.1 Repeatability and Measurement Uncertainty 27 2.3.2 Comparison of numerical and experimental Impedance Curves 32 2.4 Harmonicity Analysis of the Resonator 35 2.4.1 The Role of the Resonator 35 2.4.2 The reed equivalent Volume 35 2.4.3 Harmonicity Map 36 2.5 Summary 38 3 Characterization of the Double Reed Mouthpiece 41 3.1 Physical Model of the Double-Reed 41 3.1.1 Working Principle 41 3.1.2 Structural Mechanical Characteristics 42 3.1.3 Fluid Mechanical Characteristics 44 3.2 Measurement of Reed Parameters 49 3.2.1 Quasi-stationary Measurement 49 3.2.2 Dynamic Measurement 50 3.3 Construction of an Artificial Mouth 52 3.3.1 Requirements Profile 52 3.3.2 Generic Design 53 3.3.3 The artificial Lip 54 3.3.4 Air Supply 55 3.3.5 Sensors and Data Acquisition 57 3.3.6 Experimental setup 59 3.4 Summary 59 4 Modeling Realistic Embouchures with Reed Parameters 61 4.1 Reed Channel Geometry and Flow Characteristics 61 4.1.1 The Double-Reed as a Flow Duct 61 4.1.2 Bernoulli Flow-Model with Pressure Losses 65 4.1.3 Discussion of the Model 68 4.2 Quasi-static Interaction of Flow and Reed-Channel 72 4.2.1 Pressure-driven Deformation of the Duct Intake 72 4.2.2 Reed-Flow Model including Channel Deformation 75 4.2.3 Influence of Model Parameters 76 4.2.4 Experimental Verification 78 4.3 Effect of the Embouchure on the Reed-Flow 81 4.3.1 Adjustment of the Initial Slit Height 81 4.3.2 Quasi-static Flow in the Deformed Reed-Channel 83 4.3.3 Simplified empirical Model including a Lip Force 85 4.4 Summary 93 5 Survey of Performance Characteristics of the Modern German Bassoon 5.1 Experimental Procedure and Data Analysis 95 5.1.1 Description of the Experiment 95 5.1.2 Time Domain Analysis 97 5.1.3 Spectral Analysis – Period Synchronized Sampling 98 5.1.4 Spectral Centroid and Formants 99 5.1.5 Embouchure parameters 100 5.2 Observations on the Bassoon under Operating Conditions 105 5.2.1 Excitation Parameter Ranges 106 5.2.2 Characteristics of the radiated Sound 110 5.2.3 Reed Pressure Waveform Analysis 115 5.2.4 Summarizing Overview 118 5.3 Performance Control with the Embouchure 120 5.3.1 Register-dependent Embouchure Characteristics 120 5.3.2 Intonation Corrections 123 5.3.3 Sound Color Adjustments 127 5.3.4 Relation to the acoustical Properties of the Resonator 129 5.4 Summary 137 6 Conclusion 139 6.1 Summary 139 6.2 Outlook 141