References of "Valeau, Vincent"
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See detailModélisation des champs sonores en acoustique architecturale par un processus de diffusion
Picaut, Judicaël; Billon, Alexis ULg; Valeau, Vincent et al

Conference (2010, April)

La modélisation des champs sonores en acoustique architecturale est d'autant plus complexe que la géométrie d'étude est elle-même complexe. En particulier, le domaine de propagation peut présenter de ... [more ▼]

La modélisation des champs sonores en acoustique architecturale est d'autant plus complexe que la géométrie d'étude est elle-même complexe. En particulier, le domaine de propagation peut présenter de nombreux volumes couplés de tailles très différentes, connectés par de faibles surfaces de couplage. Dans ces conditions, les formulations analytiques classiques, basées par exemple sur la théorie de la réverbération, ou les méthodes numériques, basées par exemple sur des méthodes de tracé de rayons ou de faisceaux sonores, sont difficilement applicables, voire impossibles. Ces dernières années, une solution alternative, fondée sur l'utilisation d'une équation de diffusion pour la densité d'énergie sonore, a été développée et validée. Dans ce présent travail, nous présentons les développements permettant ainsi de modéliser les champs sonores en acoustique des salles, en prenant en compte les difféerents phénomènes propagatifs mis en jeu, tel que l'atténuation atmosphérique, l'absorption par les parois, la transmission acoustique à travers les cloisons et la réflexion mixte au niveau des surfaces. Dans un second temps, nous présentons la méthode retenue pour la résolution numérique des équations de diffusion mises en jeu. A cet effet, une interface logicielle a été spécialement développée, permettant de manipuler de manière fonctionnelle les données géométriques et acoustiques du problème, avant l'exécution d'un logiciel de calcul multi-physique, en s'affranchissant ainsi du formalisme spécifique associé au modèle de diffusion. Cette interface permet ensuite le post-traitement de l'ensemble des résultats, notamment afin de déterminer et de représenter différents paramètres classiques d'acoustique des salles (niveaux sonores, temps de réverbération. . . ). [less ▲]

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See detailSound Field Modeling in Architectural Acoustics using a Diffusion Equation Based Model
Fortin, Nicolas; Picaut, Judicaël; Billon, Alexis ULg et al

Conference (2009, October)

In this paper, an implementation of a model for room-acoustic predictions in COMSOL Multiphysics is presented. The model (called diffusion model) is based on the solving of diffusion equations instead of ... [more ▼]

In this paper, an implementation of a model for room-acoustic predictions in COMSOL Multiphysics is presented. The model (called diffusion model) is based on the solving of diffusion equations instead of classical wave equations and allows simulating the sound propagation in complex geometries at high frequency. Instead of using COMSOL Multiplysics to solve directly the problem, a specific tool has been developed. It is composed of a user-friendly interface (I-Simpa) which manipulates all the physical data of the problem (geometries, acoustic properties and elements…) and generates an interoperability script to execute COMSOL Multiplysics via the generation of .m file scripts. Then, numerical results are processed by I-Simpa for the acoustic post-treatment and results display, like sound levels, reverberation times… [less ▲]

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See detailNumerical simulations of the sound propagation in non rectilinear streets
Billon, Alexis ULg; Picaut, Judicaël; Valeau, Vincent et al

Conference (2009, October)

At high frequencies, the sound propagation can be approximated by the propagation of sound particles which are reflected and absorbed at the boundaries. This propagation follows then a transport process ... [more ▼]

At high frequencies, the sound propagation can be approximated by the propagation of sound particles which are reflected and absorbed at the boundaries. This propagation follows then a transport process. In urban canyons, this transport process can be reduced to a diffusion process. The resultant model allows one to obtain the spatial distribution of the acoustical energy in a street in a few seconds using a classical finite elements program. This diffusion model has been previously validated in rectilinear streets for different geometrical and acoustical parameters. In this paper, more complex geometries such as varying cross-sections, bents and streets crossings are dealt with. As the diffusion model only models the reverberated sound field, diffraction effects on the direct sound field at streets corners are added. The obtained results are then compared to scale model experiments. [less ▲]

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See detailExperimental investigation of the aeroacoustic coupling between the non-planar modes of a resonator and the misaligned jet-slot oscillator
Glesser, Martin; Valeau, Vincent; Billon, Alexis ULg et al

in Acta Acustica United with Acustica (2009), 95(3), 512-518

The jet-slot oscillator is a source of aeroacoustic self-sustained tones resulting from the impingement of the vortical structures of a plane jet onto a slotted plate. The coupling of this type of ... [more ▼]

The jet-slot oscillator is a source of aeroacoustic self-sustained tones resulting from the impingement of the vortical structures of a plane jet onto a slotted plate. The coupling of this type of aeroacoustic source with high-order acoustic resonances of the flow-supply duct is experimentally studied, in the particular case where the jet-exit and the obstacle are misaligned in the spanwise direction. An experimental setup based on microphones and hot-wire probes is used to investigate this coupling. It is shown that: (i) the misaligned jet-slot oscillator can be coupled to non-planar (transverse) modes of the flow-supply duct, (ii) the vortex tubes spanwise morphology is governed by the phase pattern of the excited modes, and (iii) the impingement of the vortices on the inclined obstacle tends to occur in phase in the spanwise direction, in order to enhance the coherence of the interaction along the slot. An investigation of the excited modes as a function of the plate inclination angle and of the streamwise slot position was then conducted. For small inclination angles, the coupling involves a planar mode or a combination of planar and transverse modes. For higher misalignment angles the coupling involves transverse modes or “opposite-transverse” modes, generating vortices with an inclination angle opposite to the plate inclination angle. The influence of the coupling nature on tone production (emission frequency and SPL) was thus evaluated. [less ▲]

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See detailAn empirical diffusion model for acoustic prediction in rooms with mixted specular and diffuse refections
Foy, Cédric; Valeau, Vincent; Billon, Alexis ULg et al

in Acta Acustica United with Acustica (2009), 95(1), 97-105

In this paper, a modification to the room-acoustic diffusion model is proposed to take different amounts of wall scattering into account. An extensive set of numerical simulations using a cone-tracing ... [more ▼]

In this paper, a modification to the room-acoustic diffusion model is proposed to take different amounts of wall scattering into account. An extensive set of numerical simulations using a cone-tracing software has first been carried out, in order to highlight the impact of the scattering coefficient on the diffusion process in rooms, in terms of sound pressure levels. An iterative method is then proposed to identify, for a given value of the wall’s scattering coefficient, the diffusion constant that allows the stationary sound field to be governed by a diffusion process, regardless of the room’s geometry. Using this method, an empirical law can be proposed between the diffusion constant and the scattering coefficient. The empirical diffusion model is then compared to scale model experiments, as well as to other models from the literature, with a satisfactory agreement for the sound pressure level. However, the empirical diffusion model fails to predict the sound decay for rooms with perfectly specularly reflecting surfaces, due to the inherent concept of a diffusion process. [less ▲]

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See detailIntroducing atmospheric attenuation within a diffusion model room-acoustic predictions
Billon, Alexis ULg; Picaut, Judicaël; Foy, Cédric et al

in Journal of the Acoustical Society of America (2008), 123(6), 4040-4043

This paper presents an extension of a diffusion model for room acoustics to handle the atmospheric attenuation. This phenomenon is critical at high frequencies and in large rooms to obtain correct ... [more ▼]

This paper presents an extension of a diffusion model for room acoustics to handle the atmospheric attenuation. This phenomenon is critical at high frequencies and in large rooms to obtain correct acoustic predictions. An additional term is introduced in the diffusion equation as well as in the diffusion constant, in order to take the atmospheric attenuation into account. The modified diffusion model is then compared with the statistical theory and a cone-tracing software. Three typical room-acoustic configurations are investigated: a proportionate room, a long room and a flat room. The modified diffusion model agrees well with the statistical theory (when applicable, as in proportionate rooms) and with the cone-tracing software, both in terms of sound pressure levels and reverberation times. [less ▲]

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See detailOn the use of diffusion equations to model the acoustics of coupled rooms
Billon, Alexis ULg; Valeau, Vincent; Picaut, Judicaël et al

in Journal of the Acoustical Society of America (2008), 123(5), 3910-3910

he acoustics of coupled rooms are characterized by energy exchanges through apertures and/or partition walls. The use of systems of diffusion equations allows to predict the temporal and spatial energy ... [more ▼]

he acoustics of coupled rooms are characterized by energy exchanges through apertures and/or partition walls. The use of systems of diffusion equations allows to predict the temporal and spatial energy distributions in these configurations quite accurately. In this presentation, the diffusion formalism for room acoustics-prediction is summarized. The systems of equations to be solved in the case of coupling through an aperture and through a partition wall are presented. For two rooms coupled through an aperture (two classrooms connected through an open door), the results obtained with the diffusion model are compared to experimental data, in terms of sound pressure levels and sound decays. On the other hand, for the case of two classrooms connected through a partition wall, the diffusion model is compared to experimental data in terms of sound pressure level difference only. Finally, an engineering application is presented in the configuration involving a workroom including multiple sound sources (e.g., machines) connected to offices through open and closed doors. [less ▲]

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See detailModeling the sound transmission coupled through partition walls using a diffusion model
Billon, Alexis ULg; Foy, Cédric; Picaut, Judicaël et al

in Journal of the Acoustical Society of America (2008), 123(6), 4261-4271

In this paper, a modification of the diffusion model for room acoustics is proposed to account for sound transmission between two rooms, a source room and an adjacent room, which are coupled through a ... [more ▼]

In this paper, a modification of the diffusion model for room acoustics is proposed to account for sound transmission between two rooms, a source room and an adjacent room, which are coupled through a partition wall. A system of two diffusion equations, one for each room, together with a set of two boundary conditions, one for the partition wall and one for the other walls of a room, is obtained and numerically solved. The modified diffusion model is validated by numerical comparisons with the statistical theory for several coupled-room configurations by varying the coupling area surface, the absorption coefficient of each room, and the volume of the adjacent room. An experimental comparison is also carried out for two coupled classrooms. The modified diffusion model results agree very well with both the statistical theory and the experimental data. The diffusion model can then be used as an alternative to the statistical theory, especially when the statistical theory is not applicable, that is, when the reverberant sound field is not diffuse. Moreover, the diffusion model allows the prediction of the spatial distribution of sound energy within each coupled room, while the statistical theory gives only one sound level for each room. [less ▲]

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See detailDiffusion-based models for predicting sound fields in rooms with mixed specular and diffuse reflection
Foy, Cédric; Billon, Alexis ULg; Valeau, Vincent et al

Conference (2007, September)

A diffusion model, based on the numerical solution of a diffusion equation, was developed in the past to give accurate predictions of the sound-pressure level and of the sound decay at any location in a ... [more ▼]

A diffusion model, based on the numerical solution of a diffusion equation, was developed in the past to give accurate predictions of the sound-pressure level and of the sound decay at any location in a single enclosure or in coupled rooms. However, this model is limited to rooms with diffusely reflecting walls. In this study, two methods are presented to extend this model to rooms with mixed specular and diffuse reflections, defined by the classical room-acoustics scattering coefficient. The first method models the reverberant field by using a modified diffusion process, with an empirical diffusion constant departing from the theoretical one based on the mean free path. The set of these coefficients, which depend on the scattering coefficient, has been found empirically to fit the results given by a ray-tracing program. The second method is a hybrid approach. The reverberant sound field due to the diffuse reflections is first obtained with the original diffusion model. Then the sound field due to the specular reflections is modelled with an image-source model. The results given by the two approaches are compared to experimental data obtained for several types of rooms (a classroom, an office and some long rooms). [less ▲]

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See detailAeroacoustics coupling of a misaligned jet-slot-oscillator with non-planar modes of a resonator
Glesser, Martin; Billon, Alexis ULg; Valeau, Vincent et al

Conference (2007, September)

The impingement of a plane jet on a slotted plate produces a “jet-slot oscillator” emitting acoustic tones. The coupling of such tones with high-order acoustic resonances of the flow-supply duct (i.e ... [more ▼]

The impingement of a plane jet on a slotted plate produces a “jet-slot oscillator” emitting acoustic tones. The coupling of such tones with high-order acoustic resonances of the flow-supply duct (i.e., above the first transverse mode cut-off frequency) is studied experimentally , in the particular case where the jet-exit and the obstacle are misaligned in the spanwise direction. An experimental set-up based on microphones and hot-wire probes is used to investigate the effect of the slot angle on the sound production mechanism. The aligned jet-slot oscillator is first studied, showing that the parallelism between the jet exit and the slot imposes the excitation of planar modes of the resonator only. Conversely, the misaligned jet-slot oscillator appears to be coupled with a combination of planar and transverse modes. The induced spanwise variation of the acoustic field phase has two consequences. First, it compensates the difference of vortices convection time in the spanwise direction, due to the obstacle misalignment. Second, it enhances the spanwise coherence of the aeroacoustic source produced by the jet-slot interaction: the vortex-tubes are shed in an oblique direction which tends to be parallel to the obstacle. [less ▲]

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See detailModelling the sound transmission through separation walls using a diffusion model
Billon, Alexis ULg; Foy, Cédric; Valeau, Vincent et al

Conference (2007, September)

The diffusion model has been used successfully to evaluate the acoustic behaviour of a system of coupled rooms connected through a coupling aperture. In this paper, an extension of this model is proposed ... [more ▼]

The diffusion model has been used successfully to evaluate the acoustic behaviour of a system of coupled rooms connected through a coupling aperture. In this paper, an extension of this model is proposed to deal with the propagation of sound energy through a partition wall. The diffusion model can be considered as an extension of the statistical theory to none diffuse sound fields. Numerical comparisons with the statistical theory are then carried out. The following parameters are varied: its transmission loss of the separation wall, its surface, the coupled room’s absorption coefficient and the coupled room’s volume. The agreement between the statistical theory and the diffusion model is very good. [less ▲]

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See detailSound field modeling in architectural acoustics using a diffusion equation
Picaut, Judicaël; Valeau, Vincent; Billon, Alexis ULg et al

Conference (2006, December)

A numerical approach is proposed to model the reverberated sound field in rooms. The model is based on the numerical implementation of a diffusion model enabling spatial variations of the sound energy ... [more ▼]

A numerical approach is proposed to model the reverberated sound field in rooms. The model is based on the numerical implementation of a diffusion model enabling spatial variations of the sound energy within a room, unlike the statistical theory. The proposed method allows to take into account most of complex phenomena encountered in room acoustics, like mixed reflections on walls (diffuse and specular), low and high absorption on walls, atmospheric attenuation, fitted zones. Moreover, the model can be applied to complex geometries, like multiple coupled rooms of different sizes. In this paper, the model and its numerical implementation are first detailed. Then, an application is proposed for a complex geometry defined by multiple coupled rooms with fitting objects, including low and high absorption on walls, in terms of sound level and reverberation times. The main interest of the model is that such approach requires less computational time in comparison with common approaches like ray-tracing simulations. [less ▲]

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See detailSifflements produits par un jet plan accordé heurtant une plaque fendue
Billon, Alexis ULg; Glesser, Martin; Valeau, Vincent et al

Scientific conference (2006, August)

Sous certaines conditions défavorables, les bouches de soufflage des circuits de ventilation peuvent émettre des sifflements désagréables. Ce phénomène, modélisé par l’impact d’un jet plan sur une plaque ... [more ▼]

Sous certaines conditions défavorables, les bouches de soufflage des circuits de ventilation peuvent émettre des sifflements désagréables. Ce phénomène, modélisé par l’impact d’un jet plan sur une plaque fendue, est étudié expérimentalement. Les fréquences des deux instabilités principales, l’instabilité de la couche de cisaillement et le mode de battement du jet, de l’écoulement sans obstacle permettent de définir le domaine d’existence de la fréquence la plus énergétique des sons auto-entretenus produits. Le cas particulier d’un jet accordé est étudié. Cette donnée permet d’anticiper la stratégie de réduction la plus adaptée. [less ▲]

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See detailFrequency halving due to vortex pairing for the jet-slot oscillator
Billon, Alexis ULg; Glesser, Martin; Valeau, Vincent et al

Conference (2006, July)

At the outlet of the HVCA systems, whistling can occur, due to self-sustained oscillations. In this study, the ventilation outlet is modelled by a free plane subsonic jet impinging on a slotted plate ... [more ▼]

At the outlet of the HVCA systems, whistling can occur, due to self-sustained oscillations. In this study, the ventilation outlet is modelled by a free plane subsonic jet impinging on a slotted plate, leading to self-sustained tones production; this configuration is known as the jet-slot oscillator. The tone's frequency can be predicted through the vortex dynamics within the flow. For jet velocities higher than 16m/s, the tones couple with the flow-supply-duct’s resonances. These resonances control the vortex dynamics and reinforce the sound production, of about 20dB. Moreover, when the distance from the jet exit to the plate is increased and reaches 4.5 times the jet height, the fundamental frequency of the tones is suddenly halved due to some vortex pairing occurring at the end of the potential core of the jet. In this paper, the vortex pairing is observed with three different experimental techniques. Firstly, comparison between the radiated and the in-duct acoustic fields is conducted. Then the energy transfer from the fundamental to the sub-harmonics of the shear layer's velocity fluctuations is observed with anemometric measurements. Finally high speed flow visualizations are performed and allow to link the vortex impingement on the plate to the sound production. [less ▲]

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See detailPrediction of the acoustics of coupled rooms with the acoustic-diffusion model
Valeau, Vincent; Billon, Alexis ULg; Hodgson, Murray et al

Conference (2006, June)

A general model is proposed to simulate the acoustics of coupled rooms. It is based on a diffusion equation, solved numerically to perform acoustic predictions. The presence of scattering objects –or the ... [more ▼]

A general model is proposed to simulate the acoustics of coupled rooms. It is based on a diffusion equation, solved numerically to perform acoustic predictions. The presence of scattering objects –or the “fittings”– is also taken into account. Distinct sub-volumes can be defined, representing either coupled volumes or zones with different fitting characteristics. Some sample results are presented, and compared with ray-tracing results and experimental data. Two situations are assessed: two coupled classrooms, and a room divided into two zones, one empty, one fitted. The diffusion-model predictions match the other data satisfactorily, both in terms of sound attenuation and sound decay. Diffusion-based results are obtained with the advantage of low computational time compared to ray-tracing results. [less ▲]

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See detailNon-confined jet-slot-cavity oscillator: flow-acoustic interaction modeling
Glesser, Martin; Billon, Alexis ULg; Valeau, Vincent et al

Conference (2006, May)

Disturbing whistling due to self-sustained oscillations can be produced in a wide variety of geometries where a sheared subsonic flow impinges on a downstream obstacle. When those self-sustained ... [more ▼]

Disturbing whistling due to self-sustained oscillations can be produced in a wide variety of geometries where a sheared subsonic flow impinges on a downstream obstacle. When those self-sustained oscillations are coupled with an acoustic resonator, the acoustic production can reach dramatically high levels. The configuration known as jet-slot oscillator is studied in the particular case where the resonator is the flow-supply duct and the source region is unconfined. This sound production is due to flow-acoustic interactions and can be modeled by using the vortex-sound theory. It allows one to express the acoustic power generated by the interaction between the acoustic, velocity, and vorticity fields. They are obtained separately by using rather simple models together with experimental input data. The vorticity field is modeled with the assumption that the shear layer is rectilinear and the vorticity is only concentrated on discrete vortex-points convected at constant velocity. The vorticity being non null only in the shear layer, the velocity field is calculated only in this region where it is equal to the vortices convection speed. The source region dimensions being small compared to the acoustic wavelength, this field is considered, in harmonic regime, as a sinusoidal temporal fluctuation of a potential field. This field can be taken as resulting from the flow produced by the radiation of the flow supply duct's acoustic resonance. It is obtained by solving the Poisson equation in a simplified geometry obtained by Schwarz-Christoffel mapping. The configuration studied here presents some specific problems which must be addressed to correctly model its sound production. Experimentations are used to specify the missing parameters. The major one is the synchronisation between the vorticity field and the acoustic field which governs the way that the vortices interact with the resonant acoustic field. At last, comparison between experimental data and modeling results permits to validate the study, in terms of emitted frequency. Further developments of the model will allow to predict the emitted sound level. [less ▲]

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See detailDynamique des structures tourbillonnaires participant à la production du bruit de fente
Glesser, Martin; Billon, Alexis ULg; Valeau, Vincent et al

Conference (2006, April)

Des sons auto-entretenus (sifflements de forte intensité) peuvent être produits par les bouches de soufflage des systèmes de ventilation. L'impact du jet produit par la bouche sur une grille de protection ... [more ▼]

Des sons auto-entretenus (sifflements de forte intensité) peuvent être produits par les bouches de soufflage des systèmes de ventilation. L'impact du jet produit par la bouche sur une grille de protection située en aval induit une perturbation pouvant remonter l'écoulement et venir exciter le jet à sa naissance, établissant ainsi une boucle d'auto-entretien. Pour certains nombres de Reynolds et distances "sortie du jet / obstacle", un couplage entre les sons auto-entretenus et le conduit de soufflage est observé. La résonance du conduit contrôle alors la fréquence et amplifie le niveau sonore. Cette étude s'intéresse à la production sonore résultant de ce couplage. Les structures tourbillonnaires crées dans les couches de cisaillement du jet jouent un rôle prépondérant : la synchronisation entre leur création ou leur impact sur l'obstacle et le champ acoustique rayonné par le conduit résonnant influe fortement sur la production sonore. Or les résultats disponibles dans la littérature pour des configurations géométriques ressemblantes ne permettent pas de clarifier cette synchronisation. Un dispositif expérimental où un jet plan rectangulaire heurte une plaque fendue (configuration géométrique appelée bruit de fente) est donc étudié à l'aide de mesures vélocimétriques. La comparaison de la fluctuation du signal de vitesse dans le cône potentiel du jet (directement lié à la vitesse acoustique) et du signal de vitesse dans la couche de cisaillement (contenant des informations sur le passage des structures tourbillonnaires) permet de clarifier la dynamique de ces structures. L'information obtenue permet alors d'évaluer la synchronisation entre le champ acoustique et le champ tourbillonnaire. Cette étude contribuera à terme a l'implémentation d'un modµele du bruit de fente basé sur la théorie aéroacoustique de Howe. [less ▲]

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See detailDifférentes estimations du libre parcours moyen en acoustique des salles : influence sur l’estimation de l’énergie acoustique par un modèle de diffusion
Foy, Cédric; Billon, Alexis ULg; Valeau, Vincent et al

Conference (2006, April)

La plupart des outils de prévision en acoustique des salles sont basés sur le principe du tir de rayons. La précision des résultats dépend alors du nombre de rayons choisi, nécessairement important quand ... [more ▼]

La plupart des outils de prévision en acoustique des salles sont basés sur le principe du tir de rayons. La précision des résultats dépend alors du nombre de rayons choisi, nécessairement important quand la géométrie simulée est grande et/ou disproportionnée, ce qui implique alors des temps de calcul élevés. Pour ce type de géométrie, une méthode alternative, basée sur la résolution numérique d’une équation de diffusion, permet en revanche de réaliser des prévisions acoustiques au prix d’un coût numérique modeste. Ce modèle repose en particulier sur un coefficient de diffusion caractérisant la pièce. Ce coefficient est théoriquement proportionnel au libre parcours moyen (LPM) du local considéré, vérifiant classiquement l’expression 4V/S (V étant le volume de la salle, S la surface des parois). Il est souvent admis que cette valeur est valide pour une salle de dimensions homogènes et dans le cas d’un champ réverbéré diffus. Néanmoins, dans la présente étude nous montrons que pour des locaux particulièrement allongés ou plats, l’atténuation sonore, directement dépendante du coefficient de diffusion, est surestimée par ce modèle. Il en est de même pour des locaux dont la loi de réflexion aux parois s’écarte d’une loi de Lambert. Ainsi, afin d’améliorer les performances du modèle de diffusion, la solution envisagée consiste d’une part, à réaliser un calcul numérique préliminaire du LPM et d’autre part, à considérer les approches analytiques alternatives du LPM rencontrées dans la littérature. La méthode numérique retenue est basée sur le suivi de particules sonores, et permet d’établir le LPM à partir de l’ensemble des distances de collision entre deux parois, pour des conditions de réflexion quelconques. Les résultats de ces approches analytiques et numériques sont présentés en terme d’atténuation sonore pour un local plat et un local allongé, et sont comparés à ceux issus d’autres méthodes numériques. [less ▲]

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See detailValidation expérimentale d’un modèle de diffusion pour l’acoustique des locaux couplés
Billon, Alexis ULg; Picaut, Judicaël; Valeau, Vincent et al

Conference (2006, April)

La modélisation du champ sonore au sein de locaux couplés acoustiquement au moyen d’ouvertures a déjà fait l’objet de nombreuses études. Néanmoins, des modèles à la fois rapides et précis restent encore à ... [more ▼]

La modélisation du champ sonore au sein de locaux couplés acoustiquement au moyen d’ouvertures a déjà fait l’objet de nombreuses études. Néanmoins, des modèles à la fois rapides et précis restent encore à développer, parti-culièrement dans le cas où trois ou quatre salles sont associées. Récemment, un modèle basé sur une équation de diffusion a été appliqué avec succès pour la prévision du champ sonore réverbéré au sein d’un ensemble de deux locaux couplés. Dans cette étude, l’équation de diffusion est résolue numériquement en trois dimensions à l’aide d’une méthode par éléments finis. Cette résolution permet ainsi d’obtenir le niveau et la décroissance sonore en tout point du domaine considéré, au prix d’un faible temps de calcul (quelques minutes). Dans cette étude, les résultats obtenus sont validés, à la fois en termes de niveau du champ sonore et temps de réverbération, à l’aide d’une campagne expérimentale menée dans deux salles de cours couplées entre elles. De plus, une comparaison est réalisée avec des résultats issus de la théorie statistique classique et d’un logi-ciel commercial de tir de rayons largement répandu. Les résultats obtenus montrent un bon accord entre le modèle de diffusion et les expériences. En revanche, la théorie stati-stique ne permet pas de rendre compte précisément de la distribution spatiale et de la décroissance de l’énergie sonore. Enfin, le gain de temps par rapport au logiciel de tir de rayons est très important. [less ▲]

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See detailOn the use of a diffusion model for acoustically coupled rooms
Billon, Alexis ULg; Valeau, Vincent; Sakout, Anas et al

in Journal of the Acoustical Society of America (2006), 120(4), 2043-2054

A numerical model is proposed to predict the reverberant sound field in a system of two coupled volumes that are connected through an open aperture. The model is based on the numerical implementation of a ... [more ▼]

A numerical model is proposed to predict the reverberant sound field in a system of two coupled volumes that are connected through an open aperture. The model is based on the numerical implementation of a diffusion model that has already been applied to predict the sound-energy distribution and the sound decay in single rooms. In comparison with the statistical theory, the proposed approach permits the prediction of the sound field by taking into account the sound source location and the receiver locations as well as the transition from one room to the other at the coupling aperture. Moreover, the diffusion model results match satisfactorily the experimental data in terms of sound-pressure level and reverberation times, both in the room containing the source and in the receiving room. Simulations with a ray-based model are also carried out, leading to results similar to those of the diffusion model, but at a cost of larger computation times. [less ▲]

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