Showing results 21 to 40 of 128
  Ray-tracing modelling of the diffraction by half-planes based on the energy flow lines conceptBillon, Alexis  ; Embrechts, Jean-Jacques Conference (2011, June 28) Detailed reference viewed: 14 (2 ULg)3D Audio Acquisition and Reproduction SystemsEvrard, Marc ; André, Cédric ; Embrechts, Jean-Jacques et alScientific 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 ▲] Detailed reference viewed: 103 (10 ULg) Theoretical Determination of the Random-Incidence Scattering Coefficients of Infinite Rigid Surfaces with a Periodic Rectangular Roughness ProfileEmbrechts, Jean-Jacques ; Billon, Alexis 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 ▲] Detailed reference viewed: 44 (5 ULg)Research activities in 3D sound and Auralization (in Intelsig)Embrechts, Jean-Jacques Poster (2010, December) Detailed reference viewed: 24 (3 ULg)Adding 3D Sound to 3D Cinema: Identification and Evaluation of Different Reproduction TechniquesAndré, Cédric ; Embrechts, Jean-Jacques ; Verly, Jacques 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 ▲] Detailed reference viewed: 152 (34 ULg)Adding 3D sound to 3D cinema: new challenges and perspectivesAndré, Cédric ; Embrechts, Jean-Jacques ; Verly, Jacques Poster (2010, May 18) Detailed reference viewed: 78 (12 ULg) Effect of ground scattering on noise barriers efficiencyBillon, Alexis ; Nemerlin, Jean ; Embrechts, Jean-Jacques 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 ▲] Detailed reference viewed: 30 (8 ULg)Real-time auralization of industrial noiseEmbrechts, Jean-Jacques ; Bos, Lionel 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 ▲] Detailed reference viewed: 32 (7 ULg)Recherche des intersections rayon-surfaces par classement préférentiel dans un logiciel d'acoustique des sallesLesoinne, Stéphane ; Embrechts, Jean-Jacques in Actes du 10è Congrès Français d'Acoustique (2010, April) Detailed reference viewed: 22 (13 ULg)Evaluation du temps de mélange à partir de la distribution temporelle du libre parcours dans une salleBillon, Alexis ; ; Embrechts, Jean-Jacques 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 ▲] Detailed reference viewed: 45 (12 ULg)Introduction to colorimetryEmbrechts, Jean-Jacques Learning material (2010) Detailed reference viewed: 15 (4 ULg)Adding sound to movies: Historical trends and new challenges of 3D cinemaAndré, Cédric ; Embrechts, Jean-Jacques ; Verly, Jacques 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 ▲] Detailed reference viewed: 130 (28 ULg)An interactive and real-time 3D auralization system for room acoustics (the AURALIAS project)Bos, Lionel ; Embrechts, Jean-Jacques in Proceedings of the 3D Stereo Media congress, Liege 2010 (2009, December) Detailed reference viewed: 96 (9 ULg)Objective study of spatial attributes in the room impulse response's late part and their relevance for auralizationBillon, Alexis ; Embrechts, Jean-Jacques in Proceedings of the Euronoise 2009 Congress (2009, October) Detailed reference viewed: 20 (8 ULg)An interactive and real-time based auralization sytem for room acoustics, implementing directional impulse responses and multiple audio reproduction modules for spatialization (the AURALIAS project)Bos, Lionel ; Embrechts, Jean-Jacques Conference (2009) Detailed reference viewed: 101 (9 ULg)Acoustical design of a listening studio for auralization sessionsEmbrechts, Jean-Jacques ; Duthoit, Fabienne Conference (2009) Detailed reference viewed: 20 (6 ULg)Real time auralization: a low cost updating of ray-tracing results induced by modifications of the acoustical spaceBillon, Alexis ; Embrechts, Jean-Jacques Conference (2009) Detailed reference viewed: 15 (7 ULg)Size-adaptive spherical receptor acceleration method for acoustical ray tracingLesoinne, Stéphane ; Embrechts, Jean-Jacques in Proceedings of the 5th Forum Acusticum "Acoustics '08" (2008, July) Detailed reference viewed: 32 (13 ULg) Mathematical modelization of reduced luminance coefficients for dry road surfaces; Embrechts, Jean-Jacques in Lighting Research & Technology (2008), 40 Detailed reference viewed: 22 (5 ULg)Acoustique du bâtimentEmbrechts, Jean-Jacques Learning material (2008) Detailed reference viewed: 29 (3 ULg) |
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