Study of the undercutting of woodwind toneholes using particle image velocimetry

The undercutting of toneholes has been practised for centuries with the aim of improving the tuning and playability of woodwind instruments. The influence of undercutting on tuning can be understood in terms of linear acoustic theory. Its effect on other playing characteristics is thought to lie in its reduction of local non-linear flow phenomena (boundary layer separation and the formation of jets and vortices) at the tonehole. Particle Image Velocimetry (PIV) is used to examine the oscillating airflow around a model woodwind tonehole. Velocity and vorticity information is obtained and compared for a square-edged tonehole and an undercut tonehole at a variety of sound levels. The upstream, internal edge of the tonehole is found to be the location of the most significant local non-linear flow behaviour. Undercutting is found to reduce the strength of local non-linear flow phenomena at a given sound level. Microphone measurements carried out in a reverberation chamber show that undercutting the tonehole also reduces the harmonic distortion introduced to the radiated pressure signal by the non-linear flow. Proper Orthogonal Decomposition (POD) is then applied to PIV data of oscillating flow at the end of a tube. It is used to approximately separate the acoustic field from the induced local non-linear flow phenomena. The POD results are then used to approximate the percentage of kinetic energy present in the non-linear flow. POD analysis is applied to the case of flow around the two toneholes. It shows a smaller transfer of kinetic energy to non-linear flow effects around the undercut tonehole at a given sound level. The dependence of the local non-linear flow kinetic energy on Strouhal number is considered

Generic resonator models for real-time synthesis of reed and brass instruments

International audienceFrom accurate measurements of bore profiles of various reed and brass instruments, a common and simplified geometrical model made of three parts totalizing seven geometrical parameters is proposed. From this geometry, it is shown that a good approximation of the input impedance can be obtained by a combination of two lumped elements gathered in series and parallel with a distributed element. Each element is approximated and discretized in order to end up with costless digital filters representing the impedance impulse response. These filters require the order of twenty multiplication/additions per sample and their coefficients are analytically expressed as functions of the geometrical parameters. The choice of the geometry and the time discretization schemes are validated both through comparison with continuous models and through the estimation of the geometrical parameters via a global optimization procedure, using measured input impedance curves

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

The influence of the vocal tract on the attack transients in clarinet playing

When playing single-reed woodwind instruments, players can modulate the spectral content of the airflow in their vocal tract, upstream of the vibrating reed. In an empirical study with professional clarinettists (Np=11), blowing pressure and mouthpiece pressure were measured during the performance of Clarinet Concerto excerpts. By comparing mouth pressure and mouthpiece pressure signals in the time domain, a method to detect instances of vocal tract adjustments was established. Results showed that players tuned their vocal tract in both clarion and altissimo registers. Furthermore, the analysis revealed that vocal tract adjustments support shorter attack transients and help to avoid lower bore resonances

Acoustique et respiration dans le jeu musical des instruments à vent : application aux flûtes

This thesis presents an acoustical study of flute-like instruments, which is developed by the analysis of flautist’s breathing. The flautist acquires during his musical background an expert control of his instrument. The control developed by the musician directly depends on the freedoms and constraints provided by the musician musical expertise, his respiratory physiology, the musical tasks and the acoustic behavior of the flute. Studying the playing techniques requires us to consider the flautist and the instrument as a whole.First, this work focuses on the study of the acoustic response of the flute through two studies: one on the contribution of the linear acoustics in the design of a new instrument with a flute-maker, the other on the influence of the position of the flautist’s lips. This work allows us to highlight irregularities in the acoustic behavior of the flute according to the fingerings, and leads us to study how the flautist compensates them. Secondly, we study the respiratory strategies developed by the musician while playing, in order to obtain detailed analysis and understanding of relationships between respiratory and aeroacoustic control parameters in a musical context. We answer two questions: how does a flute player adapt his breathing and playing to musical tasks, and when does the musical playing begin. Finally, we were interested in the respiratory efforts developed by the musician, in terms of work and power. A new question is asked: how does the flautist use his respiratory system in order to achieve and/or to highlight a musical intention.Cette thèse présente une étude acoustique des instruments de musique de type flûte, enrichie par l'analyse de la respiration chez les flûtistes.Le flûtiste acquiert au cours de son parcours musical un contrôle expert du jeu de son instrument. Les contrôles développés par le musicien dépendent des libertés et contraintes apportées par son expertise musicale, sa physiologie respiratoire, la consigne musicale et la réponse acoustique de la flûte. Etudier les techniques de jeu nécessite de considérer le flûtiste et son instrument comme un ensemble.D'une part, ce travail porte sur l'étude de la réponse acoustique de la flûte à travers deux études: l'une concernant l'apport de l'acoustique linéaire lors de la conception d'un nouvel instrument par un facteur, l'autre portant sur l'influence de la position des lèvres du flûtiste. Ce travail permet de mettre en lumière les irrégularités du comportement acoustique de la flûte selon le doigté et amène à étudier comment le flûtiste les compense.D'autre part, nous étudions les stratégies respiratoires développées par le musicien au cours du jeu, afin d'obtenir une analyse et une compréhension fines des relations entre les paramètres de contrôle respiratoires et aéro-acoustiques dans un contexte musical. Nous répondons à deux questions : comment le flûtiste adapte sa respiration aux consignes musicales, et quand commence le jeu musical. Enfin, nous nous sommes intéressés aux efforts respiratoires développés par le musicien, en termes de travail et puissance. Une nouvelle question est posée : comment le flûtiste met à profit son système respiratoire afin de réaliser et/ou de faire entendre une intention musicale

Viscothermal models for wind musical instruments

This work focuses on thermal and viscous effects on linear wave propagation inside a pipe. It aims at understanding the ground on which are built many dissipative propagating wave models found in the musical acoustics literature, in order to quantify, as much as possible, the underlying assumptions and model errors which are performed. The Navier-Stokes (NS) equations, which are nonlinear and expressed in the 3 dimensions of space, are the starting point of all models. Thermoviscous (or viscothermal) equations are derived from NS equations mainly after linearization and assumptions on the gas state equation. Analytical or numerical solutions to these equations can be proposed, after modifying more of less the original system. These derived models are summed-up in a global sketch of the underlying hypotheses. What is observed is that the thermal and viscous effects are mainly confined near the boundaries of the pipe, in regions called "boundary layers", whose lengths depend on the physical coefficients and the harmonic regime. These thermal and viscous effects can therefore be neglected far from the boundaries (where a standard 3D Helmholtz wave equation holds). These procedures can lead to 3D models, describing the propagation of the pressure field in all the domain or only a part of it, or 1D models, describing the propagation of the mean pressure across a pipe section. Some other 1D models are obtained from derived 3D models, and describe the propagation of the pressure near the boundary layer. The time dependancy of these derived models can be very intricate because the model derivation is done in the harmonic regime, and nonlocal operators can arise. An additional modelling step can lead to local time-domain 1D models. An assessment of some of these 3D and 1D models is proposed, aiming at a quantitative estimation of the model errors with respect to their domains of validity, and at a comparison between some models for simple geometries.Ce travail porte sur les effets visqueux et thermiques se manifestant lors de la propagation d'ondes linéaires dans un tuyau. Il vise à comprendre le fondement sur lequel s'appuient de nombreux modèles d'ondes dissipatives courants en acoustique musicale, afin de quantifier autant que possible, les hypothèses sous jacentes et les erreurs de modèle effectuées. Les équations de Navier-Stokes (NS), qui sont non linéaires et formulées dans les trois dimensions de l'espace, forment le point de départ de tous les modèles. Les équations thermovisqueuses (ou viscothermiques) sont dérivées des équations de NS essentiellement après une étape de linéarisation et certaines hypothèses sur l'équation d'état du gaz. Des solutions analytiques ou numériques peuvent être proposées, après des modifications plus ou moins profondes du système original. Ces modèles dérivés sont résumés dans un schéma global précisant les hypothèses effectuées. Ce que l'on peut observer est que les effets thermiques et visqueux sont essentiellement confinés à proximité des bords du tuyau, dans une région abritant les "couches limites", dont la taille caractéristique dépend des coefficients physiques et du régime harmonique. Ces effets thermiques et visqueux peuvent donc être négligés loin des bords (où une équation de Helmholtz 3D standard est valide). Ces procédures peuvent mener à l'établissement de modèles 3D qui décrivent la propagation du champ de pression dans tout le domaine ou seulement une sous partie, ou de modèles 1D qui décrivent la propagation de la pression moyenne sur une section du tuyau. D'autres modèles 1D peuvent découler des modèles 3D, et décrivent la propagation de la pression au voisinage des couches limites. La dépendance en temps de ces modèles dérivés est parfois très délicate car leur dérivation est faite dans le régime harmonique, faisant apparaitre des opérateurs non locaux. Une étape supplémentaire de modélisation peut aboutir à des modèles 1D locaux en temps. Ce travail propose une évaluation de certains de ces modèles (3D et 1D), à travers une estimation quantitative des erreurs de modèles en lien avec leurs domaines de validité, ainsi qu'une comparaison entre les modèles pour des géométries simples

Wooden Musical Instruments - Different Forms of Knowledge: Book of End of WoodMusICK COST Action FP1302

International audienceMusical instrument are fundamental tools of human expression that reveal and reflect historical, technological, social and cultural aspects of times and people. These three-dimensional, polyma-teric objects-at times considered artworks, other times technical objects-are the most powerful way to communicate emotions and to connect people and communities with the surrounding world. The participants in WoodMusICK (WOODen MUSical Instrument Conservation and Knowledge) COST Action FP1302 have aimed to combine forces and to foster research on wooden musical instruments in order to preserve, develop and disseminate knowledge on musical instruments in Europe through inter-and transdisciplinary research. This four-year program, supported by COST (European Cooperation in Science and Technology), has involved a multidisciplinary and multinational research group composed of curators, conservators/restorers, wood, material and mechanical scientists, chemists, acousticians, organologists and instrument makers. The goal of the COST Action was to improve the knowledge and preservation of wooden musical instruments heritage by increasing the interaction and synergy between different disciplines