References of "Embrechts, Jean-Jacques"
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See detailSearching for a theoretical relation between reverberation and the scattering coefficients of surface in a room
Embrechts, Jean-Jacques ULg

in Proceedings of the Acoustics 2012 Nantes conference (2012, April)

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See detailAURALIAS: an audio-immersive system for auralizing room acoustics projects
Embrechts, Jean-Jacques ULg

Conference (2011, December)

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See detailMicrophone arrays fundamentals
Embrechts, Jean-Jacques ULg

Conference (2011, November 23)

Microphone arrays are essentially directional sensors. They are therefore mainly used for locating, identifying, isolating, measuring and recording individual sound sources. The main principles governing ... [more ▼]

Microphone arrays are essentially directional sensors. They are therefore mainly used for locating, identifying, isolating, measuring and recording individual sound sources. The main principles governing the directivity of microphone arrays are reviewed: phase differences between signals create constructive and destructive interferences, depending on the direction of the sound source. Moreover, signal processing is applied to provide “beamforming”, i.e. beam shaping and steering. Contrary to continuous antenna, discrete arrays can create aliasing, which can result in false detections of sound sources. The delay-and-sum and filter-and-sum beamformers are described. Finally, as simple beamformers are often frequency dependent, some solutions to obtain constant (broad-band) directivity are presented. [less ▲]

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See detailObject-Based Sound Re-Mix for Spatially Coherent Audio Rendering of an Existing Stereoscopic-3D Animation Movie
Evrard, Marc ULg; André, Cédric ULg; Verly, Jacques ULg et al

Conference (2011, October 20)

While 3D cinema is becoming more established, little effort has focused on the general problem of producing a 3D sound scene spatially coherent with the visual content of a stereoscopic-3D (s-3D) movie ... [more ▼]

While 3D cinema is becoming more established, little effort has focused on the general problem of producing a 3D sound scene spatially coherent with the visual content of a stereoscopic-3D (s-3D) movie. The perceptual relevance of such spatial audiovisual coherence is of significant interest. In order to carry out such experiments, it is necessary to have an appropriate s-3D movie and its corresponding 3D audio track. This paper presents the procedure followed to obtain this joint 3D video and audio content from an existing animated s-3D film, problems encountered, and some of the solutions employed. [less ▲]

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See detailNumerical evidence of mixing in rooms using the free path temporal distribution
Billon, Alexis ULg; Embrechts, Jean-Jacques ULg

in Journal of the Acoustical Society of America (2011), 130(3), 13811389

The ergodic propriety of a room has strong effects on its reverberation. If the room is ergodic, the reverberation can be broken up in two steps: a deterministic process followed by a stochastic one. The ... [more ▼]

The ergodic propriety of a room has strong effects on its reverberation. If the room is ergodic, the reverberation can be broken up in two steps: a deterministic process followed by a stochastic one. The late reverberation can be then modeled by a reverberation algorithm instead of more computationally consuming methods. In this study, the free path temporal distribution obtained by ray-tracing is used as an indicator of the room’s mixing: the energetic average of the path lengths is computed at each time step. Ergodic rooms are thus characterized by rapidly convergent distributions. The free path value becomes independent of time. On the other hand, path selection mechanism and orbits are observed in non-ergodic rooms. The transition time from the deterministic process to the stochastic one is also studied through the evaluation of the room’s time constant. It is shown that its value depends only on the mean free path and the boundaries scattering value. An empirical expression is obtained which agrees well with simulations carried out in a concert hall. This transition time from a deterministic model to a stochastic one can be used to speed up the acoustical predictions and auralizations in ergodic rooms. [less ▲]

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See detailAcoustic comfort of air-treatment systems: influence of factors related to room acoustics
Minard, Antoine; Goujard, Bertrand; Sakout, Anas et al

Conference (2011, June 30)

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See detailRay-tracing modelling of the diffraction by half-planes based on the energy flow lines concept
Billon, Alexis ULg; Embrechts, Jean-Jacques ULg

in Proceedings of the Forum Acusticum 2011 Congress (2011, June 28)

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See detail3D Audio Acquisition and Reproduction Systems
Evrard, Marc ULg; André, Cédric ULg; Embrechts, Jean-Jacques ULg et al

Scientific conference (2011, February 23)

This presentation introduces two different research projects dealing with 3D audio for 3D-stereoscopic movies. The first project “3D audio acquisition for real time applications” studies the best method ... [more ▼]

This presentation introduces two different research projects dealing with 3D audio for 3D-stereoscopic movies. The first project “3D audio acquisition for real time applications” studies the best method for acquiring a full 3D audio soundscape on location and for processing it in real-time for further reproduction. The second project “Adding 3D sound to 3D cinema” is aimed towards the study of reproducing a 3D soundscape consistent with the visual content of a 3D-stereoscopic movie. These projects are linked together since they present both ends of the 3D audio chain. They are conducted as part of the “MEDIATIC – 3D MEDIA” project, which concerns the production, the processing, and the exploitation of rich audiovisual content, with a specific focus on 3D video imagery. [less ▲]

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See detailTheoretical Determination of the Random-Incidence Scattering Coefficients of Infinite Rigid Surfaces with a Periodic Rectangular Roughness Profile
Embrechts, Jean-Jacques ULg; Billon, Alexis ULg

in Acta Acustica United with Acustica (2011), 97

An exact solution is developed for the sound field reflected by an infinite rigid rough surface with a periodic rectangular profile. The random-incidence scattering coefficient of this surface is derived ... [more ▼]

An exact solution is developed for the sound field reflected by an infinite rigid rough surface with a periodic rectangular profile. The random-incidence scattering coefficient of this surface is derived from the numerical calculation of this solution for several directions of the incident plane wave. Scattering coefficients’ values are given in this paper for a great number of configurations by varying the geometrical parameters of the periodic profile, leading to a very detailed description of the scattering properties of this kind of profile. In particular, it is shown that, when the ratio H/L of the depth to the spatial period of the profile is small, the key parameter is H/, the ratio of the depth of the profile to the wavelength. The random-incidence scattering coefficient tends to increase with this ratio, as long as H/ is less than 0.3. This evolution is similar to gaussian and sine-shaped profiles analysed in previous studies. For H/ >0.3, the coefficient’s value oscillates while converging to an asymptotic value which depends on the width of the wells. Resonance effects have also been highlighted for periodic rectangular profiles, in particular by comparing the computed scattering coefficients with the few measured values published in the scientific literature. The scattering coefficients’ values published in this paper can be introduced in room acoustics’ models to characterize periodic rectangular surfaces, provided that their dimensions are much greater than the wavelength. Additional measurements and BEM computations are required to deeply analyse the influence of the finite size and the acoustical absorption of real surfaces having this profile. [less ▲]

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See detailResearch activities in 3D sound and Auralization (in Intelsig)
Embrechts, Jean-Jacques ULg

Poster (2010, December)

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See detailAdding 3D Sound to 3D Cinema: Identification and Evaluation of Different Reproduction Techniques
André, Cédric ULg; Embrechts, Jean-Jacques ULg; Verly, Jacques ULg

in Audio Language and Image Processing (ICALIP), 2010 International Conference on (2010, November 24)

Very little research has been conducted so far into the general problem of producing a 3D soundscape consistent with the visual content of a 3D-stereoscopic movie. First, the following 3D sound ... [more ▼]

Very little research has been conducted so far into the general problem of producing a 3D soundscape consistent with the visual content of a 3D-stereoscopic movie. First, the following 3D sound reproduction techniques are reviewed: Vector Base Amplitude Panning (VBAP), binaural and transaural techniques, Wave Field Synthesis (WFS) and Ambisonics. Second, the new challenges of 3D cinema are introduced. Third, we reconsider each 3D audio technique in the light of these challenges. We find that, at least in theory, a completely personalized soundscape is needed and that, due to various technical reasons, only binaural reproduction through headphones is able to accurately produce a 3D soundscape consistent with a 3D-stereo movie in a theater environment. [less ▲]

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See detailEffect of ground scattering on noise barriers efficiency
Billon, Alexis ULg; Nemerlin, Jean ULg; Embrechts, Jean-Jacques ULg

Conference (2010, April 29)

Noise barriers are popular devices to mitigate the impact of roads or railway noise on the community. So, heavy works have been devoted to improve their efficiency, both through their shapes and their ... [more ▼]

Noise barriers are popular devices to mitigate the impact of roads or railway noise on the community. So, heavy works have been devoted to improve their efficiency, both through their shapes and their building materials. In this work, the effect of ground scattering on the insertion loss created by a straight hard thin screen is investigated using a 1/10th scale model. The ground possesses thus a repetitive structure to induce scattering. Measurements are conducted on both sides of the screen and comparisons are drawn with a flat ground configuration. [less ▲]

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See detailReal-time auralization of industrial noise
Embrechts, Jean-Jacques ULg; Bos, Lionel ULg

in Proceedings of the Institute of Acoustics & Belgian Acoustical Society (2010, April)

A real-time and interactive auralization system has been developed within the research project Auralias (www.auralias.be). Originally conceived for architectural acoustics applications, this system is now ... [more ▼]

A real-time and interactive auralization system has been developed within the research project Auralias (www.auralias.be). Originally conceived for architectural acoustics applications, this system is now applied to auralize the effect of noise reduction solutions in industrial halls. Some specific characters of this kind of problems are first identified: several sources with intermittent noise emission, rectangular hall geometries, quite reverberant spaces, sound level calibration needed. A protocol for the application of the auralizer is then tested on an example, from the room acoustics model to the final sound rendering. [less ▲]

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See detailRecherche des intersections rayon-surfaces par classement préférentiel dans un logiciel d'acoustique des salles
Lesoinne, Stéphane ULg; Embrechts, Jean-Jacques ULg

in Actes du 10è Congrès Français d'Acoustique (2010, April)

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See detailEvaluation du temps de mélange à partir de la distribution temporelle du libre parcours dans une salle
Billon, Alexis ULg; Dirix, Simon; Embrechts, Jean-Jacques ULg

in Actes du 10ème Congrès Français d'Acoustique (2010, April)

Dans un espace clos où se mélangent les nombreuses ondes réfléchies, diffusées et diffractées par les surfaces, la propagation de l’énergie sonore peut être décomposée en deux étapes: tout d’abord, un ... [more ▼]

Dans un espace clos où se mélangent les nombreuses ondes réfléchies, diffusées et diffractées par les surfaces, la propagation de l’énergie sonore peut être décomposée en deux étapes: tout d’abord, un processus déterministe pour lequel il est possible d’identifier individuellement chaque contribution, suivi d’un processus stochastique pour lequel les contributions doivent être globalisées et vues comme un processus quasi-aléatoire. Le seuil de transition entre les deux comportements est matérialisé dans l’échogramme par le temps de mélange. Dans cette étude, le temps de mélange est analysé en regard de la distribution temporelle du libre parcours. Celle-ci est obtenue numériquement à l’aide du programme de tir de rayons large bande Salrev. Dans un premier temps, le mélange est identifié au travers du caractère asymptotique de cette distribution. Le temps de mélange est alors défini comme la durée (mesurée à partir de l’instant d’émission au départ de la source) nécessaire pour atteindre ce comportement asymptotique. A partir de cette définition du temps de mélange sont étudiées les influences de divers paramètres géométriques et acoustiques. Ensuite, trois applications pour des salles de concert sont réalisées. Cette étude montre que les valeurs obtenues pour le temps de mélange convergent vers celles observées expérimentalement, à condition que les parois de la salle soient suffisamment diffusantes. [less ▲]

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See detailIntroduction to colorimetry
Embrechts, Jean-Jacques ULg

Learning material (2010)

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See detailAdding sound to movies: Historical trends and new challenges of 3D cinema
André, Cédric ULg; Embrechts, Jean-Jacques ULg; Verly, Jacques ULg

Conference (2009, December 03)

Very little research has been done so far in producing 3D sound and audio that are consistent with the 3D stereo video being viewed by the spectator. After a review of the currently used techniques for ... [more ▼]

Very little research has been done so far in producing 3D sound and audio that are consistent with the 3D stereo video being viewed by the spectator. After a review of the currently used techniques for theater sound reproduction, this talk presents new challenges of 3D cinema in terms of sound reproduction and analyse which known 3D audio techniques are able to tackle those challenges. [less ▲]

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See detailAn interactive and real-time 3D auralization system for room acoustics (the AURALIAS project)
Bos, Lionel ULg; Embrechts, Jean-Jacques ULg

in Proceedings of the 3D Stereo Media congress, Liege 2010 (2009, December)

Detailed reference viewed: 110 (10 ULg)