2,238 research outputs found

    Regime change thresholds in flute-like instruments: influence of the mouth pressure dynamics

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    Since they correspond to a jump from a given note to another one, the mouth pressure thresholds leading to regime changes are particularly important quantities in flute-like instruments. In this paper, a comparison of such thresholds between an artificial mouth, an experienced flutist and a non player is provided. It highlights the ability of the experienced player to considerabily shift regime change thresholds, and thus to enlarge its control in terms of nuances and spectrum. Based on recent works on other wind instruments and on the theory of dynamic bifurcations, the hypothe- sis is tested experimentally and numerically that the dynamics of the blowing pressure influences regime change thresholds. The results highlight the strong influence of this parameter on thresholds, suggesting its wide use by experienced musicians. Starting from these observations and from an analysis of a physical model of flute-like instruments, involving numerical continuation methods and Floquet stability analysis, a phenomenological modelling of regime change is proposed and validated. It allows to predict the regime change thresholds in the dynamic case, in which time variations of the blowing pressure are taken into account

    Effect of Changing the Vocal Tract Shape on the Sound Production of the Recorder: An Experimental and Theoretical Study

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    Changing the vocal tract shape is one of the techniques which can be used by the players of wind instruments to modify the quality of the sound. It has been intensely studied in the case of reed instruments but has received only little attention in the case of air-jet instruments. This paper presents a first study focused on changes in the vocal tract shape in recorder playing techniques. Measurements carried out with recorder players allow to identify techniques involving changes of the mouth shape as well as consequences on the sound. A second experiment performed in laboratory mimics the coupling with the vocal tract on an artificial mouth. The phase of the transfer function between the instrument and the mouth of the player is identified to be the relevant parameter of the coupling. It is shown to have consequences on the spectral content in terms of energy distribution among the even and odd harmonics, as well as on the stability of the first two oscillating regimes. The results gathered from the two experiments allow to develop a simplified model of sound production including the effect of changing the vocal tract shape. It is based on the modification of the jet instabilities due to the pulsating emerging jet. Two kinds of instabilities, symmetric and anti-symmetric, with respect to the stream axis, are controlled by the coupling with the vocal tract and the acoustic oscillation within the pipe, respectively. The symmetry properties of the flow are mapped on the temporal formulation of the source term, predicting a change in the even / odd harmonics energy distribution. The predictions are in qualitative agreement with the experimental observations

    Systems control theory applied to natural and synthetic musical sounds

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    Systems control theory is a far developped field which helps to study stability, estimation and control of dynamical systems. The physical behaviour of musical instruments, once described by dynamical systems, can then be controlled and numerically simulated for many purposes. The aim of this paper is twofold: first, to provide the theoretical background on linear system theory, both in continuous and discrete time, mainly in the case of a finite number of degrees of freedom ; second, to give illustrative examples on wind instruments, such as the vocal tract represented as a waveguide, and a sliding flute

    An acoustic model for automatic control of a slide flute

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    International audienceIn this paper, we consider the problem of modeling and control of a slide flute : a kind of recorder without finger holes but which is ended by a piston mechanism to modify the length of the resonator. A previous study has been done (see [3]), but with a very simple boundary condition for the mouth, corresponding to an ideal situation assuming that the acoustic pressure is zero at the entrance of the resonator. In this work, we have taken into account a more realistic model, describing the coupling effects between the jet and the pipe. The jet is obtained by blowing through a flue channel and formed by flow separation at the flue exit, and finally directed towards a sharp edge, called the labium. The resulting structure can then be seen as a nonlinear oscillator coupled with the pipe which is a linear acoustic resonator. The pressure obtained through this model has been compared to the pressure measured on an actual instrument, a recorder closed at its end. A modal analysis is then performed using the linearized boundary conditions which can also be used to compute the suitable blowing pressure and the suitable pipe length to obtain a desired fundamental frequency or equivalently a desired pitch. This will constitute the basis of our control algorithm. A possible musical application of such a device is to build a flue instrument with a pitch independent of the dynamical level

    Flute-like musical instruments: a toy model investigated through numerical continuation

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    Self-sustained musical instruments (bowed string, woodwind and brass instruments) can be modeled by nonlinear lumped dynamical systems. Among these instruments, flutes and flue organ pipes present the particularity to be modeled as a delay dynamical system. In this paper, such a system, a toy model of flute-like instruments, is studied using numerical continuation. Equilibrium and periodic solutions are explored with respect to the blowing pressure, with focus on amplitude and frequency evolutions along the different solution branches, as well as "jumps" between periodic solution branches. The influence of a second model parameter (namely the inharmonicity) on the behaviour of the system is addressed. It is shown that harmonicity plays a key role in the presence of hysteresis or quasi-periodic regime. Throughout the paper, experimental results on a real instrument are presented to illustrate various phenomena, and allow some qualitative comparisons with numerical results

    Sound Generation by a Turbulent Flow in Musical Instruments - Multiphysics Simulation Approach -

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    Total computational costs of scientific simulations are analyzed between direct numerical simulations (DNS) and multiphysics simulations (MPS) for sound generation in musical instruments. In order to produce acoustic sound by a turbulent flow in a simple recorder-like instrument, compressible fluid dynamic calculations with a low Mach number are required around the edges and the resonator of the instrument in DNS, while incompressible fluid dynamic calculations coupled with dynamics of sound propagation based on the Lighthill's acoustic analogy are used in MPS. These strategies are evaluated not only from the viewpoint of computational performances but also from the theoretical points of view as tools for scientific simulations of complicated systems.Comment: 6 pages, 10 figure files, to appear in the proceedings of HPCAsia0

    The search for a microtonal Flute

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    This thesis investigates the possibility of a microtonal flute and the practicality of playing such an instrument. Microtonality is concerned with the intervals between any two consecutive notes in a tuning system. Standard tuning is not considered microtonal, however, any other system can be. There are various tuning systems that are used throughout the world. These include Equal Tempered Tuning, Just Intonation, Chinese Pentatonic, and Javanese Slendro tuning. An instrument with the ability to change between any tuning systems would be considered fully microtonal. In this thesis the frequencies and spectrums produced by the Boehm flute are investigated prior to investigating the 'plunger' flute and the 'sieve' flutes. Within a given register the plunger can be considered as a fully microtonal instrument however, results from the plunger flute show that the instrument could not play the full range, and that the size of the bore greatly impeded the result. The Sieve flutes produced a clearer sound, which was more like the Boehm flute than the Plunger flute was. However, the results show that for the two sieve flutes produced, neither of them could play in any complete tuning system. Due to the tone hole positions not matching those on the Boehm flute the instruments were unable to play in 12-ET (Equal Tempered). However, the results were not entirely unsatisfactory and with the modifications suggested for the sieve flute it is believed that a tuning system other than 12-ET would be playable. This thesis examines some of the other possibilities that could be used to develop and subsequently produce a suitable playable microtonal flute. This thesis briefly considers how the ideas from the search for a microtonal flute could be used in the search for other microtonal woodwind instrument

    Vortices on Sound Generation and Dissipation in Musical Flue Instruments

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    Musical flue instruments such as the pipe organ and flute mainly consist of the acoustic pipe resonance and the jet impinging against the pipe edge. The edge tone is used to be considered as the energy source coupling to the pipe resonance. However, jet-drive models describing the complex jet/pipe interaction were proposed in the late 1960s. Such models were more developed and then improved to the discrete-vortex model and vortex-layer model by introducing fluid-dynamical viewpoint, particularly vortex sound theory on acoustic energy generation and dissipation. Generally, the discrete-vortex model is well applied to thick jets, while the jet-drive model and the vortex-layer model are valid to thin jets used in most flue instruments. The acoustically induced vortex (acoustic vortex) is observed near the amplitude saturation with the aid of flow visualization and is regarded as the final sound dissipation agent. On the other hand, vortex layers consisting of very small vortices along both sides of the jet are visualized by the phase-locked PIV and considered to generate the acceleration unbalance between both vortex layers that induces the jet wavy motion coupled with the pipe resonance. Vortices from the jet visualized by direct numerical simulations are briefly discussed
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