CNRS LIMSI

Orsay, France

CNRS LIMSI

Orsay, France
SEARCH FILTERS
Time filter
Source Type

Parseihian G.,University Paris - Sud | Parseihian G.,Aix - Marseille University | Jouffrais C.,French National Center for Scientific Research | Katz B.F.G.,University Paris - Sud | Katz B.F.G.,CNRS LIMSI
Frontiers in Neuroscience | Year: 2014

Sound localization studies over the past century have predominantly been concerned with directional accuracy for far-field sources. Few studies have examined the condition of near-field sources and distance perception. The current study concerns localization and pointing accuracy by examining source positions in the peripersonal space, specifically those associated with a typical tabletop surface. Accuracy is studied with respect to the reporting hand (dominant or secondary) for auditory sources. Results show no effect on the reporting hand with azimuthal errors increasing equally for the most extreme source positions. Distance errors show a consistent compression toward the center of the reporting area. A second evaluation is carried out comparing auditory and visual stimuli to examine any bias in reporting protocol or biomechanical difficulties. No common bias error was observed between auditory and visual stimuli indicating that reporting errors were not due to biomechanical limitations in the pointing task. A final evaluation compares real auditory sources and anechoic condition virtual sources created using binaural rendering. Results showed increased azimuthal errors, with virtual source positions being consistently overestimated to more lateral positions, while no significant distance perception was observed, indicating a deficiency in the binaural rendering condition relative to the real stimuli situation. Various potential reasons for this discrepancy are discussed with several proposals for improving distance perception in peripersonal virtual environments. © 2014 Parseihian, Jouffrais and Katz.


Auvray M.,CNRS LIMSI | Rohde M.,Bielefeld University
Frontiers in Human Neuroscience | Year: 2012

Researchers in social cognition increasingly realize that many phenomena cannot be understood by investigating offline situations only, focusing on individual mechanisms and an observer perspective. There are processes of dynamic emergence specific to online situations, when two or more persons are engaged in a real-time interaction that are more than just the sum of the individual capacities or behaviors, and these require the study of online social interaction. Auvray et al.'s (2009) perceptual crossing paradigm offers possibly the simplest paradigm for studying such online interactions: two persons, a one-dimensional space, one bit of information, and a yes/no answer. This study has provoked a lot of resonance in different areas of research, including experimental psychology, computer/robot modeling, philosophy, psychopathology, and even in the field of design. In this article, we review and critically assess this body of literature. We give an overview of both behavioral experimental research and simulated agent modeling done using the perceptual crossing paradigm. We discuss different contexts in which work on perceptual crossing has been cited. This includes the controversy about the possible constitutive role of perceptual crossing for social cognition. We conclude with an outlook on future research possibilities, in particular those that could elucidate the link between online interaction dynamics and individual social cognition. © 2012 Auvray and Rohde.


Boronska K.,CNRS LIMSI | Tuckerman L.S.,CNRS LIMSI
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

Rayleigh-Bénard convection in a cylindrical container can take on many different spatial forms. Motivated by the results of Hof [Phys. Fluids 11, 2815 (1999)], who observed coexistence of several stable states at a single set of parameter values, we have carried out simulations at the same Prandtl number, that of water, and a radius-to-height aspect ratio of two. We have used two kinds of thermal boundary conditions: perfectly insulating sidewalls and perfectly conducting sidewalls. In both cases we obtain a wide variety of coexisting steady and time-dependent flows. © 2010 The American Physical Society.


Grouin C.,CNRS LIMSI
AMIA ... Annual Symposium proceedings / AMIA Symposium. AMIA Symposium | Year: 2011

The CHA2DS2-VASc score is a 10-point scale which allows cardiologists to easily identify potential stroke risk for patients with non-valvular fibrillation. In this article, we present a system based on natural language processing (lexicon and linguistic modules), including negation and speculation handling, which extracts medical concepts from French clinical records and uses them as criteria to compute the CHA2DS2-VASc score. We evaluate this system by comparing its computed criteria with those obtained by human reading of the same clinical texts, and by assessing the impact of the observed differences on the resulting CHA2DS2-VASc scores. Given 21 patient records, 168 instances of criteria were computed, with an accuracy of 97.6%, and the accuracy of the 21 CHA2DS2-VASc scores was 85.7%. All differences in scores trigger the same alert, which means that system performance on this test set yields similar results to human reading of the texts.


Katz B.F.G.,CNRS LIMSI
Journal of the Acoustical Society of America | Year: 2015

The room acoustic parameter "strength of sound G" is a measure of room amplification relative to a 10 m free-field reference. Due to this reference requirement, G is often considered excessively difficult to measure. Standards require reference measurements using reverberation or anechoic chambers. While possible for well-equipped laboratories, this is impractical for most practitioners. Considering the entire measurement chain, stability of amplifier and converter gains must be identical between on-site and calibration measurements, which cannot always be assured. An in situ calibration method is proposed, taking advantage of the full hall dataset. Results show significant advantages compared to previous methods. © 2015 Acoustical Society of America.


Bredin H.,CNRS LIMSI
ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings | Year: 2012

We investigate the use of speaker diarization (SD) and automatic speech recognition (ASR) for the segmentation of audiovisual documents into scenes. We introduce multiple monomodal and multimodal approaches based on a state-of-the-art algorithm called generalized scene transition graph (GSTG). First, we extend the latter with the use of semantic information derived from both SD and ASR. Then, multimodal fusion of color histograms, SD and ASR is investigated at various point of the GSTG pipeline (early, late or intermediate fusion). Experiments driven on a few episodes of a popular TV show indicate that SD and ASR can be successfully combined with visual information and bring an additional +11% relative increase in terms of F 1-measure for scene boundary detection over the state-of-the-art baseline. © 2012 IEEE.


Bernhard D.,CNRS LIMSI
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

This paper investigates a novel approach to unsupervised morphology induction relying on community detection in networks. In a first step, morphological transformation rules are automatically acquired based on graphical similarities between words. These rules encode substring substitutions for transforming one word form into another. The transformation rules are then applied to the construction of a lexical network. The nodes of the network stand for words while edges represent transformation rules. In the next step, a clustering algorithm is applied to the network to detect families of morphologically related words. Finally, morpheme analyses are produced based on the transformation rules and the word families obtained after clustering. While still in its preliminary development stages, this method obtained encouraging results at Morpho Challenge 2009, which demonstrate the viability of the approach. © 2010 Springer-Verlag Berlin Heidelberg.


d'Alessandro C.,CNRS LIMSI
The Journal of the Acoustical Society of America | Year: 2010

An experimental study of variations in the sound of clavichord notes at different dynamic levels is described. Radiated acoustic signal, tangent velocity and two tangent-string contact signals are synchronously measured for all 51 notes of an unfretted instrument. More than ten repeated measures are recorded in order to obtain as much variation in dynamic level as possible. The tangent motion, expressed in terms of velocity, is studied in the time and frequency domains. A model of the tangent-string contact point velocity is proposed. Then, three aspects of the sounded tones are analyzed: SPL and its relationship to tangent velocity, spectral slope, and pitch variations. These results indicate a linear relationship between sound pressure level and tangent peak log velocity. Spectral slope seems almost constant independent of tangent velocity and dynamic level. Both tangent velocity and finger pressure are shown to influence the fundamental frequency. In conclusion, controlling both finger velocity and finger pressure may prove challenging for the player, and this may explain why the sound quality of the clavichord depends so much on the players ability.


Prediction of sound fields in closed spaces can be achieved by various methods, either physical or numerical, based on different theoretical features. While the benefits and limitations of many methods have been examined for single volume spaces, there has been little effort in examining these effects for coupled volume situations. The present study presents a case study comparing theoretical, experimentally physical measurements on a scale model, and various numerical methods, namely boundary element method (BEM), finite-difference time-domain (FDTD) and ray-tracing through the commercial software CATT-Acoustic and ODEON. Although these numerical methods all use 3D numerical models of the architecture, each is different. Ray-tracing is more suitable to geometries with larger planes; BEM requires a more regular finer surface mesh; and FDTD requires a volumetric mesh of the propagation medium. A simple common geometry based on the scale model is used as a basis to compare these different approaches. Application to coupled spaces raises issues linked to later parts in the decay due to multi-slope decay rates, as well as diffraction phenomenon due to acoustic energy travelling between coupling surfaces from one volume to another. The ability of these numerical methods to adequately model these effects is the question under study. © 2013 Acoustical Society of America.


Pons M.,CNRS LIMSI
Renewable Energy | Year: 2012

It is essential to know the actual exergy input of solar radiation in a given location in order to establish the exergy budget of a solar collector or any other solar-powered process. To do so, the theories on the entropy of attenuated radiation must be re-interpreted before developing a method for evaluating the exergy flux from meteorological data. It then becomes possible to build a generic framework for describing the exergy budget of solar collectors. Three main types of exergy losses can be identified in this way. The first is related only to the type of technology chosen for the collector: flat-type collectors and highly concentrating collectors do not have same exergy losses. The second type of exergy loss is related mainly to heat dissipation, showing that all dissipated heat fluxes can be combined as the overall exergy loss. The third type is related to the utility furnished by the collector. Graphical examples are shown in a diagram that provides more information than the Sankey diagram. © 2012 Elsevier Ltd.

Loading CNRS LIMSI collaborators
Loading CNRS LIMSI collaborators