Search

International audience

Le chantier « Dendara metropole » vise a etudier les divers aspects du temple d’Hathor dans son environnement, en portant les investigations sur l’etude architecturale des monuments ainsi que sur l’exploration archeologique des quartiers d’habitations et des cimetieres. Outre la poursuite des travaux sur l’architecture monumentale, sur les secteurs associes aux fondations de Montouhotep II et sur la necropole de l’Ancien Empire, la campa...

International audience; Spatial room impulse responses (SRIRs) measured using spherical microphone arrays are seeing increasingly widespread use in reproducing room reverberation effects on three-dimensional surround sound systems (e.g., higher-order ambisonics) through multi-channel SRIR convolution. However, such measured impulse responses inevitably present a non-negligible noise floor, which may lead to a perceptible "infinite reverberation effect" when convolved with an input sound. Furthermore, individual sensor noise and momentary measurement artefacts may additionally corrupt the resulting impulse response. This paper presents a robust SRIR denoising procedure applicable to impulse responses with diffuse late reverberation tails, which can be modeled by a stochastic process. In such cases, the non-decaying frequency-dependent noise floor may be replaced by a synthesized incoherent tail parame-terized by the SRIR's energy decay envelope. It is shown that performing such tail re-synthesis in the spherical harmonic domain, using an independent zero-mean Gaussian noise for each component, preserves both the reverberation tail's frequency-dependent decay as well as its spatial coherence properties. The proposed process is then evaluated through its application to SRIRs measured in real-world conditions, and finally some aspects of performance and consistency verification are discussed.

HighlightsLogarithmically distributed auditory distances provides an apt granularity of PPSMeasuring expectation helps to interpret behavioral impact of audiotactile integrationTactile RTs follows a logarithmic decrease due to audiotactile integrationPeripersonal space is better characterized and quantified with this refinementBackgroundHumans perceive near space and far space differently. Peripersonal space, i.e. the space directly surrounding the body, is often studied using paradigms based on auditory-tactile integration. In these paradigms, reaction time to a tactile stimulus is measured in the presence of a concurrent auditory looming stimulus.New MethodWe propose here to refine the experimental procedure considering sound propagation properties in order to improve granularity and relevance of auditory-tactile integration measures. We used a logarithmic distribution of distances for this purpose. We also want to disentangle behavioral contributions of the targeted audiotactile integration mechanisms from expectancy effects. To this aim, we added to the protocol a baseline with a fixed sound distance.ResultsExpectation contributed significantly to overall behavioral responses. Subtracting it isolated the audiotactile effect due to the stimulus proximity. This revealed that audiotactile integration effects have to be tested on a logarithmic scale of distances, and that they follow a linear variation on this scale.Comparison with Existing Method(s)The granularity of the current method is more relevant, providing higher spatial resolution in the vicinity of the body. Furthermore, most of the existing methods propose a sigmoid fitting, which rests on the intuitive framework that PPS is an in-or-out zone. Our results suggest that behavioral effects follow a logarithmic decrease, thus a response graduated in space.ConclusionsThe proposed protocol design and method of analysis contribute to refine the experimental investigation of the factors influencing and modifying multisensory integration phenomena in the space surrounding the body.

International audience; Background. Humans perceive near space and far space differently. Peripersonal space (PPS), i.e. the space directly surrounding the body, is often studied using paradigms based on auditory-tactile integration. In these paradigms, reaction time (RT) to a tactile stimulus is measured in the presence of a concurrent auditory looming stimulus. New Method.We propose here to refine the experimental procedure by disentangling behavioral contributions of the targeted audiotactile integration mechanisms from expectancy effects. To this aim, we added to the protocol a baseline with a fixed sound distance. Furthermore, in order to improve the relevance of the auditory-tactile integration measures, we took into account sound propagation properties and assessed RTs for logarithmically spaced auditory distances. Results. Expectation contributed significantly to overall behavioral responses. Subtracting it isolated the audiotactile effect due to the stimulus proximity. This revealed that audiotactile integration effects have to be tested on a logarithmic scale of distances, and that they follow a linear variation on this scale. Comparison with Existing Method(s). The current method allows cleaner and more pertinent sampling measures for evaluating audiotactile integration phenomena linked to PPS. Furthermore, most of the existing methods propose a sigmoid fitting, which rests on the intuitive framework that PPS is an in-or-out zone. Our results suggest that behavioral effects follow a logarithmic decrease, thus a response graduated in space. Conclusions.The proposed protocol design and method of analysis contribute to sharpen the experimental investigation of the factors influencing and modifying multisensory integration phenomena in the space surrounding the body.

International audience; Le développement des systèmes d'assainissement s'appuie souvent sur des structures construites il y a plusieurs décennies. Ces systèmes font face à une augmentation des niveaux d'exigence qui leur sont assignés. Dans le viseur de l'arrêté de 2015 notamment, les performances par temps de pluie des systèmes de collecte. Un retour d'expériences sur les bassins d'orage mené par le Cerema fait le point sur les interrogations et les solutions trouvées par les gestionnaires. CONTEXTE DE L'ETUDE En collaboration avec l'AFB, le GEMCEA, le Ministère de la transition écologique et solidaire et les Agences de l'eau, le Cerema a réalisé un vaste retour d'expériences sur les bassins d'orage implantés sur les réseaux d'assainissement unitaires. L'objet de ce retour d'expériences était de voir, sur le terrain, comment les gestionnaires/exploitants avaient eu recours à cette technique pour optimiser le fonctionnement de leur système, notamment par temps de pluie, et de collecter des informations techniques et financières quant au fonctionnement, à la conception, au dimensionnement de ce type d'ouvrages. A travers une recherche bibliographique et de nombreux entretiens réalisés auprès de 17 maîtres d'ouvrage/exploitants, ce travail a aussi permis indirectement de recueillir les témoignages des personnes interrogées quant aux enjeux et aux problématiques auxquelles les services peuvent être confrontés, aux difficultés techniques rencontrées, souvent liées à leur contexte local, et à la façon dont les collectivités ont cherché à y remédier notamment par la construction de bassins d'orage. Le projet ayant débuté au 2nd semestre 2013 et s'étant terminé en 2018, nous avons ainsi pu être les témoins, un peu malgré nous, des interrogations des différents acteurs vis-à-vis des évolutions de la réglementation en matière d'assainissement : autosurveillance, diagnostic permanent, choix du critère de conformité du système de collecte, … ainsi que des conséquences des lois NOTRe 5 et MAPTAM 6 sur la répartition des compétences à court et moyen termes. Cette communication fait volontairement le choix de se focaliser sur les éléments recueillis qui concernent les enjeux et opportunités de l'autosurveillance et du diagnostic permanent, les démarches mises en place par les gestionnaires pour optimiser le fonctionnement de leur système et répondre aux nouveaux critères de conformité fixés par l'arrêté de 2015.

International audience; This study evaluates several methods for reporting the perceived location of real sound sources. It is well known that the method used for collecting judgments in auditory-localization experiments has a strong influence on the accuracy of a subject’s response. Previous works on auditory-localization tasks revealed that egocentric pointing methods (which are based on a body-centered coordinate system) allow for more accurate judgments than verbal reporting or exocentric pointing techniques (which are based on a 2D or 3D reporting device). Three different egocentric methods are compared: the most commonly applied “manual pointing” and “head pointing” methods, and the “proximal pointing” method, which forces the participants to indicate the apparent direction by pointing in the proximal region of the head with a marker held at the fingertips. The two first methods involve a rotation of the body of the participant, whereas the third method only involves movements of the arm(s) and hand(s) with a fixed head. Sound stimuli were presented randomly over 24 loudspeakers that were uniformly distributed on the upper hemisphere around the subject. The merits of the different methods are compared and discussed with regard to localization errors and to practical considerations. Although they show similar trends, each of the different methods affects the pointing accuracy in a specific way. The proximal pointing method, for example, is more accurate for sources located at high elevation angles. However, at rear locations close to the median plane an increased bias appears due to difficulties in performing the motor task to reach these positions. The proximal pointing method shows faster response times, which may be advantageous when planning 3D sound localization experiments.

International audience; This paper presents the Nü framework. The objective of the framework is to provide composers with a tool to control web-based audio processes on spectators smartphones during live performances. Connecting their devices to a webpage broadcasted by the performer's laptop, spectators become part of the composition: from simple sound sources to active musicians. From a Max based interface, the performer can then control the behaviours of conceptual units, referred to as Nü modules, designed for live composition (distributed room reverb, granular synthesis, etc.). Each module is composed of a pair of JavaScript classes { one for the client, another for the server { relying on the Web Audio API for audio processing, and OSC messages for parameters control. Nü is an open source project based on the Soundworks framework.

International audience; Affect, space and multisensory integration are processes that are closely linked. However, it is unclear whether the spatial location of emotional stimuli interacts with multisensory presentation to influence the emotional experience they induce in the perceiver.In this study, we used the unique advantages of virtual reality techniques to present potentially aversive crowd stimuli embedded in a natural context and to control their display in terms of sensory and spatial presentation. Individuals high in crowdphobic fear navigated in an auditory-visual virtual environment, in which they encountered virtual crowds presented through the visual channel, the auditory channel or both. They reported the intensity of their negative emotional experience at a far distance and at a close distance from the crowd stimuli. Whereas auditory-visual presentation of close feared stimuli amplified negative feelings, auditory-visual presentation of distant feared stimuli did not amplify negative feelings.This suggests that spatial closeness allows multisensory processes to modulate the intensity of the emotional experience induced by aversive stimuli. Nevertheless, the specific role of auditory stimulation must be investigated in order to better understand this interaction between multisensory, affective and spatial representation processes. This phenomenon may serve the implementation of defensive behaviors in response to aversive stimuli that are in position to threaten an individual’s feeling of security.

International audience; Ambisonics and higher order ambisonics (HOA) technologies aim at reproducing sound field either synthesised or previously recorded with dedicated microphones. Based on a spherical harmonic decomposition, the sound field is more precisely described when higher-order components are used. The presented study evaluated the perceptual and objective localisation accuracy of the sound field encoded with four microphones of order one to four and decoded over a ring of loudspeakers. A perceptual test showed an improvement of the localisation with higher order ambisonic microphones. Reproduced localisation indices were estimated for the four microphones and the respective synthetic systems of order one to four. The perceptual and objective analysis revealed the same conclusions. The localisation accuracy depends on the ambisonic order as well as the source incidence. Furthermore, impairments linked to the microphones were highlighted.

International audience; PURPOSE: This study was designed to investigate methods to help patients suffering from unilateral tinnitus synthesizing an auditory replica of their tinnitus.MATERIALS AND METHODS: Two semi-automatic methods (A and B) derived from the auditory threshold of the patient and a method (C) combining a pure tone and a narrow band-pass noise centred on an adjustable frequency were devised and rated on their likeness over two test sessions. A third test evaluated the stability over time of the synthesized tinnitus replica built with method C, and its proneness to merge with the patient's tinnitus. Patients were then asked to try and control the lateralisation of this single percept through the adjustment of the tinnitus replica level.RESULTS: The first two tests showed that seven out of ten patients chose the tinnitus replica built with method C as their preferred one. The third test, performed on twelve patients, revealed pitch tuning was rather stable over a week interval. It showed that eight patients were able to consistently match the central frequency of the synthesized tinnitus (presented to the contralateral ear) to their own tinnitus, which leaded to a unique tinnitus percept. The lateralisation displacement was consistent across patients and revealed an average range of 29dB to obtain a full lateral shift from the ipsilateral to the contralateral side.CONCLUSIONS: Although spectrally simpler than the semi-automatic methods, method C could replicate patients' tinnitus, to some extent. When a unique percept between synthesized tinnitus and patients' tinnitus arose, lateralisation of this percept was achieved.

International audience; Judging the size of a group of people is an everyday task, on which many decisions are based. In the present study, we investigated whether judgment of size of different groups of people depended on whether they were presented through the auditory channel, through the visual channel, or through both auditory and visual channels. Groups of humanoids of different sizes (from 8 to 128) were presented within a virtual environment to healthy participants. They had to judge whether there was a lot of people in each group and rate their discomfort in relation to the stimuli with Subjective Units of Distress. Our groups of 96 and 128 virtual humans were judged as crowds regardless of their sensory presentation. The sensory presentation influenced participants’ judgment of virtual human group size ranging from 8 to 48. Moreover, while the quantity judgments in the auditory condition increased linearly with the group size, participants judged the quantity of people in a logarithmic manner in the two other sensory conditions. These results suggest that quantity judgment based on auditory information in a realistic context may often involve implicit arithmetic. Even though our participants were not phobic of crowds, our findings are of interest for the field of virtual reality-based therapy for diverse disorders because they indicate that quantity judgment can potentially be altered in a sensory-specific manner in patients with fear of crowds.

International audience; Head Related Transfer Functions (HRTF) are the key features of binaural sound spatialization. Those filters arespecific to each individual and generally measured in an anechoic room using a complex process. Although theuse of non-individual filters can cause perceptual artefacts, the generalization of such measurements is hardlyaccessible for large public. Thus, many authors have proposed alternative individualization methods to prevent frommeasuring HRTFs. Examples of such methods are based on numerical modelling, adaptation of non-individualHRTFs or selection of non-individual HRTFs from a database. In this article, we propose an individualizationmethod where the best matching set of HRTFs is selected from a database on the basis of an unsupervised binauralrecording of the listener in real-life environment.

International audience; BACKGROUND: Subjective tinnitus (ST) is a frequent audiologic condition that still requires effective treatment. This study aimed at evaluating two therapeutic approaches: Virtual Reality (VR) immersion in auditory and visual 3D environments and Cognitive Behaviour Therapy (CBT).METHODS: This open, randomized and therapeutic equivalence trial used bilateral testing of VR versus CBT. Adult patients displaying unilateral or predominantly unilateral ST, and fulfilling inclusion criteria were included after giving their written informed consent. We measured the different therapeutic effect by comparing the mean scores of validated questionnaires and visual analog scales, pre and post protocol. Equivalence was established if both strategies did not differ for more than a predetermined limit. We used univariate and multivariate analysis adjusted on baseline values to assess treatment efficacy. In addition of this trial, purely exploratory comparison to a waiting list group (WL) was provided.RESULTS: Between August, 2009 and November, 2011, 148 of 162 screened patients were enrolled (VR n = 61, CBT n = 58, WL n = 29). These groups did not differ at baseline for demographic data. Three month after the end of the treatment, we didn't find any difference between VR and CBT groups either for tinnitus severity (p = 0.99) or tinnitus handicap (p = 0.36).CONCLUSION: VR appears to be at least as effective as CBT in unilateral ST patients.

In the last 4 years, we have developed a partnership between dance and neuroscience to study the relationships between body space in dance and the surrounding space, and the link between movement and audition as experienced by the dancer. The opportunity to work with a dancer/choreographer, an expert in movement, gives neuroscientists better access to the significance of the auditory-motor loop and its role in perception of the surrounding space. Given that a dancer has a very strong sense of body ownership (probably through a very accurate dynamic body schema) ( Walsh et al. 2011 ), she is an ideal subject to investigate the feeling of controlling one's own body movements, and, through them, events in the external environment ( Moore et al. 2009 , Jola et al in press). We conducted several work sessions, which brought together a choreographer/dancer, a neuroscientist, a composer, and two researchers in acoustics and audio signal processing. These sessions were held at IRCAM (Institute for Research and Coordination Acoustic/Music, Paris) in a variable-acoustics concert hall equipped with a Wave Field Synthesis (WFS) sound reproduction system and infrared cameras for motion capture. During these work sessions, we concentrated on two specific questions: 1) is it possible to extend the body space of the dancer through auditory feedback ( Maravita and Iriki 2004 )? and 2) can we alter the dancer's perception of space by altering perceptions associated with movements? We used an interactive setup in which a collection of pre-composed sound events (individual sounds or musical sentences) could be transformed and rendered in real time according to the movements and the position of the dancer, that were sensed by markers on her body and detected by a motion tracking system. The transformations applied to the different sound components through the dancer's movement and position concerned not only musical parameters such as intensity, timbre, etc. but also the spatial parameters of the sounds. The technology we used allowed us to control their trajectory in space, apparent distance and the sound reverberation ambiance. We elaborated a catalogue of interaction modes with auditory settings that changed according to the dancer's movements. An interaction mode is defined by different mappings of position, posture or gesture of the dancer to musical and spatial parameters. For instance, a sound event may be triggered if the dancer is within a certain region or if she performs a predefined gesture. More elaborated modes involved the modulation of musical parameters by continuous movements of the dancer. The pertinence at a perceptive and cognitive level of the catalogue of interactions has been tested throughout the sessions. We observed that the detachable markers could be used to create a perception of extended body space, and that the performer perceived the stage space differently according to the auditory feedback of her action. The dancer reported that each experience with the technology shed light on her need for greater awareness and exploration of her relationships with space. Real-time interactivity with sound heightened her physical awareness – as though the stage itself took on a role and became another character.

ResumenEl propósito primario de este estudio era evaluar el efecto de la retroalimentación auditiva en un sistema de realidad virtual (RV) planeado para el uso clínico y estudiar los diferentes factores que se deben tener en cuenta al construir un entorno virtual (EV) bimodal. Realizamos un experimento en el que evaluamos el desempeño espacial en pacientes con agorafobia y sujetos normales comparando dos clases de EV: visual solo (Vis) y auditivo-visual (AVis), durante sesiones separadas. Se equipó a los sujetos con un visualizador montado en la cabeza acoplado a un sistema sensor electromagnético e inmerso en una ciudad virtual. Su tarea era localizar diferentes mojones y familiarizarse con la ciudad. En la condición AVis, se equipó a los sujetos con el visualizador montado en la cabeza y auriculares, que proporcionaban un paisaje sonoro actualizado en tiempo real según su movimiento en la ciudad virtual. Aunque el desempeño general era comparable a través de las condiciones, la sensación comunicada por los sujetos de estar inmerso en el ambiente era más convincente en el entorno AVis. Sin embargo, los pacientes mostraron más síntomas de mareo de simulación en esta condición. El resultado de este estudio apunta al déficit de integración multisensorial en los pacientes con agorafobia y subrayan la necesidad de más investigaciones sobre los sistemas de RV multimodal para su uso clínico.

International audience; Most existing and arising 2D and 3D loudspeaker setups are primarily designed for cinema, and intend to render a stable frontal soundscape at the expense of precision in the reproduction of the non-frontal information. Another difficulty related to the introduction of new surround sound standards is the need for an efficient mixing approach to adapt 3D audio content to stereo and surround domestic systems. The project presented here aims at providing tools to overcome those two limitations on two-channel and 2D-multichannel setups, i.e. to enable the reproduction of 2D-and 3D-surround content on pure 2D-systems, to ensure a stable reproduction of the lateral sound images and a homogeneous envelopment of the listener.

International audience; Fear of crowds is a symptom found in agoraphobia (among others) and which has both visual and auditory relevant components. In order to examine the potential interest of auditory-visual virtual reality to treat fear of crowds, we investigated the efficiency of an auditory-visual virtual environment in evoking affective reaction. We conducted an evaluation test with healthy participants sensitive to the fear of crowds to explore the influence of auditory-visual virtual environment on affective reactions. Our application involves both high fidelity visual stimulation and interactive 3D sound. Our specific presentation of animated crowds of humans creates an environment that is highly arousing, suggesting that manipulating the sensory presentation together with the spatial location of stimulation might provide a way to modulate affective reactions.

International audience; The recent development of massive arrays of microphones or loudspeakers has stimulated numerous studies on sound field analysis and synthesis together with the development of 3D audio applications that offer a refined auditory experience. Advanced 3D audio techniques such as High Order Ambisonics (HOA) or Wave Field Synthesis (WFS) rely on large arrays of loudspeakers distributed on the room boundaries. The radiation properties of a sound source may be simulated by digitally controlled spherical loudspeaker arrays (LSA). On the recording side, spherical microphone arrays (SMA) are used to capture a soundscape or a musical ensemble performance with high spatial resolution. In room acoustics, high-resolution sound field characterization can be achieved by measuring directional room impulse responses (DRIR) that combine microphone and loudspeaker arrays. The measured DRIRs may be then exploited in convolution-based reverberators for the auralization of room acoustics with faithful rendering of its spatial attributes or for 3D audio-mixing applications. In this particular context, the sound engineer will typically want to fine tune the perceptual attributes of the original DRIRs in order to better fit the aesthetic of the mixing. Such parametric control first requires the development of an analysis-synthesis framework that operates on a space-time-frequency representation of the DRIRs. The theoretical and perceptual properties of these spatialization techniques are presented and illustrated in various contexts ranging from music performance, post-production and broadcast to virtual reality applications. Meanwhile, the ever-growing expansion of mobile devices calls for the deployment of broadcast solutions able to deliver 3D audio content and that allow for a personalized binaural rendering over headphones on the end user side.

International audience; Spatial memory is mainly studied through the visual sensory modality: navigation tasks in humans rarely integrate dynamic and spatial auditory information. In order to study how a spatial scene can be memorized on the basis of auditory and idiothetic cues only, we constructed an auditory equivalent of the Morris water maze, a task widely used to assess spatial learning and memory in rodents. Participants were equipped with wireless headphones, which delivered a soundscape updated in real time according to their movements in 3D space. A wireless tracking system (video infrared with passive markers) was used to send the coordinates of the subject's head to the sound rendering system. The rendering system used advanced HRTF-based synthesis of directional cues and room acoustic simulation for the auralization of a realistic acoustic environment. Participants were guided blindfolded in an experimental room. Their task was to explore a delimitated area in order to find a hidden auditory target, i.e., a sound that was only triggered when walking on a precise location of the area. The position of this target could be coded in relationship to auditory landmarks constantly rendered during the exploration of the area. The task was composed of a practice trial, 6 acquisition trials during which they had to memorize the localization of the target, and 4 test trials in which some aspects of the auditory scene were modified. The task ended with a probe trial in which the auditory target was removed. The configuration of searching paths allowed observing how auditory information was coded to memorize the position of the target. They suggested that space can be efficiently coded without visual information in normal sighted subjects. In conclusion, space representation can be based on sensorimotor and auditory cues only, providing another argument in favor of the hypothesis that the brain has access to a modality-invariant representation of external space.

cote interne IRCAM: Noisternig14a; None / None; National audience; The use of spherical microphone arrays (SMA) for room acoustic analysis has been widely studied in recent literature. Research has mainly focused on source localization and the extraction of room acoustic parameters from measured directional room impulse responses (DRIR). In practice, DRIRs are typically corrupted by measurement noise, which limits their use for 3-D reverberation processing and auralization. Due to the exponential energy decay, the noise floor masks especially the late part of the DRIR. In this paper we present a method for improving the signal-to-noise ratio (SNR) of measured impulse responses. This method is based on a statistical space-time-frequency model of the late reverberation decay. It first estimates the spatiotemporal energy decay relief from measured DRIRs and then replaces the corrupted part of the DRIR by a modelled diffuse sound field We applied this method to DRIRs measured in IRCAM’s variable acoustics concert hall and discuss the results.

Microphone arrays represent an attractive sound pickup solution for virtual acoustics applications where a high rejection of the acoustic environment (ambient noise and reverberation) is needed for minimizing artifacts during the postprocessing of the sound (filtering, spatialization, artificial reverberation). This study intends to evaluate, on the basis of simulations and experiments, different prototypes of microphone arrays designed at CNET. The different steps of the array processing (i.e., band filtering of subarrays, sensors weighting, beamforming, and steering) are implemented on a signal processing prototyping environment. This program is used to synthesize the impulse response of the microphone array in a real acoustic field. The input signals are the impulse responses successively measured between a source and each sensor location of the array in real rooms. The objective characterization of the array is based on classical criteria used in room acoustics and on the analysis of the time–frequenc...

A sound source can generally be characterized by three physical properties: timbre, loudness, and directivity. Although loudspeakers give a faithful reproduction of timbre and loudness, their own directivity can conflict with the directivity of the source they aim at reproducing. A general method to optimize the reproduction of any given directivity pattern with a set of independently driven sources is described. At each frequency the synthesized directivity is obtained by looking for the optimal linear combination of the elementary sources, from which the resulting acoustic field can be predicted. This method is applied to a particular source with 12 loudspeakers grouped into a few subsets in order to fit the first spherical harmonics. The comparison between the prediction and the experimental measurements shows excellent agreement. However, the synthesized figures only fit the spherical harmonics in a limited frequency range, which depends strongly on the characteristics of the electroacoustical set (nu...

This paper reviews a statistical time‐frequency model of the late diffuse reverberation in rooms. In this model, the later part of a room impulse response is described by a ‘‘time‐frequency envelope,’’ defined as the ensemble average of the time‐frequency energy distribution in the late decay. The time‐frequency envelope is independent of the source and receiver locations and is characterized by two functions of frequency: the reverberation time and a power spectral density called the ‘‘initial spectrum,’’ which corresponds to the product of the diffuse‐field transfer functions of the source and the receiver. An analysis method is described for deriving these parameters from a measured impulse response, yielding an accurate estimate of the reverberation time with arbitrary resolution in the frequency domain. The time‐frequency envelope defines a time‐dependent filter which transforms a sampled stationary Gaussian white noise into a synthetic model of the late reverberation decay. Substituting this synthetic reverberation decay to the part of an impulse response that is corrupted by measured noise, yields a restored impulse response allowing faithful auralization by convolution with anechoic source signals. The models and the methods described are illustrated on impulse responses measured in a concert hall.

cote interne IRCAM: Carpentier13a; International audience; For several decades, reverberation processors have been based on feedback delay networks that provide an efficient way to control the distribution of early reflections and the statistical properties of room reverberation. Their algorithmic architecture also allows for a flexible control through different levels of descriptors, from low-level signal processing parameters (e.g. initial delay, echo density, reverberation decay, etc.) to high-level perceptual descriptors (e.g. source presence, envelopment, reverberance, etc.). Nowadays, most reverberation units rather opt for a convolution approach exploiting a collection of room impulse responses (RIR) measured in existing performance halls or other typical rooms. To retrieve a continuous control over important perceptual dimensions, such reverberators also provide means for tweaking the original impulse response. However the tuning is generally limited to the control of the time envelope of the RIR, whereas little attention is given to the spatial distribution. The objective of this study is to develop a signal-processing environment dedicated to the analysis and re-synthesis of directional room impulse responses (DRIRs) measured with higher-order spherical microphone arrays. The analysis step results in a space-time-frequency representation of the DRIR from which various acoustical or perceptual descriptors can be extracted. During the re-synthesis step, filtering a given time-space-frequency window of the DRIR enables the tuning of these descriptors without altering the microstructure of the original DRIR.

International audience; Studies of the nature of the neural mechanisms involved in goal-directed movements tend to concentrate on the role of vision. We present here an attempt to address the mechanisms whereby an auditory input is transformed into a motor command. The spatial and temporal organization of hand movements were studied in normal human subjects as they pointed toward unseen auditory targets located in a horizontal plane in front of them. Positions and movements of the hand were measured by a six infrared camera tracking system. In one condition, we assessed the role of auditory information about target position in correcting the trajectory of the hand. To accomplish this, the duration of the target presentation was varied. In another condition, subjects received continuous auditory feedback of their hand movement while pointing to the auditory targets. Online auditory control of the direction of pointing movements was assessed by evaluating how subjects reacted to shifts in heard hand position. Localization errors were exacerbated by short duration of target presentation but not modified by auditory feedback of hand position. Long duration of target presentation gave rise to a higher level of accuracy and was accompanied by early automatic head orienting movements consistently related to target direction. These results highlight the efficiency of auditory feedback processing in online motor control and suggest that the auditory system takes advantages of dynamic changes of the acoustic cues due to changes in head orientation in order to process online motor control. How to design an informative acoustic feedback needs to be carefully studied to demonstrate that auditory feedback of the hand could assist the monitoring of movements directed at objects in auditory space.

International audience; The work presented here aims at overcoming some of the weaknesses of the 5.1 standard in terms of stability and precision of lateral sources. In addition to traditional surround panning (which relies on constant-power panning and/or multichannel microphone recordings) an extra spatialization layer based on binaural/transaural processing is introduced. This article discusses the audio signal processing and panning methods, and shows different applications scenarios and use cases.

cote interne IRCAM: Noisternig12d; None / None; National audience; Reverberation processing has been intensively studied in audio and acoustics research for many years now. Early approaches used feedback delay networks to control the temporal distribution of reflections and to simulate the statistical properties of room reverberation. Thanks to the increase in processing power and the development of low-latency convolution algorithms a new generation of reverberation processors has been developed. They apply room impulse responses (RIR) measured in real concert halls and thus guarantee naturalness and authenticity of reverberation. Extending this approach to the use of higher-order spherical microphone arrays provides the means for analyzing the spatiotemporal distribution of acoustic energy. This space-time-frequency representation of the acoustic wave field is also referred to as directional room impulse responses (DRIR) in literature. The objective of the presented work is to develop a perceptually motivated signal-processing environment based on the analysis and re-synthesis of DRIRs. It first extracts perceptual features from measured DRIRs (e.g. source presence and listener envelopment) and thus provides a perceptual signature of the measured room. The room acoustic behavior can then be modified along the various perceptual dimensions, preserving the microstructure of the original RIRs, before being re-synthesized for the use with reverberation processors.

National audience; L’Espace de Projection de l’IRCAM, salle de concert à acoustique variable a été récemment équipé d’un ambitieux dispositif de synthèse de champ sonore en temps réel. Ce système de spatialisation sonore à vocation de recherche artistique et scientifique est constitué d’une ceinture de 264 haut-parleurs régulièrement répartis autour de la scène et du public pour la diffusion en Wave Field Synthesis et d’un dôme de 75 haut-parleurs pour une diffusion tri-dimensionnelle en Ambisonics. Après un rappel des principes sur lesquels reposent ces méthodes de spatialisation et de certaines de leurs propriétés remarquables, cet article décrit les caractéristiques techniques de l’équipement et discute certaines contraintes pratiques et leurs conséquences du point de vue du traitement algorithmique.

cote interne IRCAM: Noisternig11h; None / None; National audience; Immersive 2D/3D audio for live sound and studio productions