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Within certain categories of geometric shapes, prototypical exemplars that best characterize the category have been evidenced. These geometric prototypes are classically identified through the visual and haptic perception or motor production and are usually characterized by their spatial dimension. However, whether prototypes can be recalled through the auditory channel has not been formally investigated. Here we address this question by using auditory cues issued from timbre-modulated friction sounds evoking human drawing elliptic movements. Since non-spatial auditory cues were previously found useful for discriminating distinct geometric shapes such as circles or ellipses, it is hypothesized that sound dynamics alone can evoke shapes such as an exemplary ellipse. Four experiments were conducted and altogether revealed that a common elliptic prototype emerges from auditory, visual, and motor modalities. This finding supports the hypothesis of a common coding of geometric shapes according to biological rules with a prominent role of sensory-motor contingencies in the emergence of such prototypical geometry.

International audience; Most recent vehicles are equipped with touchscreens, which replace arrays of buttons that control secondary driving functions, such as temperature level, strength of ventilation, GPS, or choice of radio stations. While driving, manipulating such interfaces can be problematic in terms of safety, because they require the drivers’ sight. In this article, we develop an innovative interface, MovEcho, which is piloted with gestures and associated with sounds that are used as informational feedback. We compare this interface to a touchscreen in a perceptual experiment that took place in a driving simulator. The results show that MovEcho allows for a better visual task completion related to traffic and is preferred by the participants. These promising results in a simulator condition have to be confirmed in future studies, in a real vehicle with a comparable expertise for both interfaces.

International audience; This article describes a listening experiment based on elicitation interviews that aims at describing the conscious experience of a subject submitted to a perceptual stimulation. As opposed to traditional listening experiments in which subjects are generally influenced by closed or suggestive questions and limited to predefined, forced choices, elicitation interviews make it possible to get a deeper insight into the listener's perception, in particular to the pre-reflexive content of the conscious experiences. Inspired by previous elicitation interviews during which subjects passively listened to sounds, this experience is based on an active task during which the subjects were asked to reproduce a sound with a stylus on a graphic tablet that controlled a synthesis model. The reproduction was followed by an elicitation interview. The trace of the graphic gesture as well as the answers recorded during the interview were then analyzed. Results revealed that the subjects varied their focus towards both the evoked sound source, and intrinsic sound properties and also described their sensations induced by the experience.

During the last 20 years, the role of musicians’ body movements has emerged as a central question in instrument practice: Why do musicians make so many postural movements, for instance, with their torsos and heads, while playing musical instruments? The musical significance of such ancillary gestures is still an enigma and therefore remains a major pedagogical challenge, since one does not know if these movements should be considered essential embodied skills that improve musical expressivity. Although previous studies established clear connections between musicians’ body movements and musical structures (particularly for clarinet, piano or violin performances), no evidence of direct relationships between body movements and the quality of the produced timbre has ever been found. In this study, focusing on the area of bowed-string instruments, we address the problem by showing that cellists use a set of primary postural directions to develop fluid kinematic bow features (velocity, acceleration) that prevent the production of poor quality (i.e., harsh, shrill, whistling) sounds. By comparing the body-related angles between normal and posturally constrained playing situations, our results reveal that the chest rotation and vertical inclination made by cellists act as coordinative support for the kinematics of the bowing gesture. These findings support the experimental works of Alexander, especially those that showed the role of head movements with respect to the upper torso (the so-called primary control) in ensuring the smooth transmission of fine motor control in musicians all the way to the produced sound. More generally, our research highlights the importance of focusing on this fundamental postural sense to improve the quality of human activities across different domains (music, dance, sports, rehabilitation, working positions, etc.).

International audience; Understanding how sounds are perceived and interpreted is an important challenge for researchers dealing with auditory perception. The ecological approach to perception suggests that the salient perceptual information that enables an auditor to recognize events through sounds is contained in specific structures called invariants. Identifying such invariants is of interest from a fundamental point of view to better understand auditory perception and is also useful to include perceptual considerations to model and control sounds. Among the different approaches used to identify perceptually relevant sound structures, vocal imitations are believed to bring a fresh perspective to the field. The main goal of this paper is to better understand how invariants are transmitted through vocal imitations. A sound corpus containing different types of known invariants obtained from an existing synthesizer was established. Participants took part in a test where they were asked to imitate the sound corpus. A continuous and sparse model adapted to the specificities of the vocal imitations was then developed and used to analyze the imitations. Results show that participants were able to highlight salient elements of the sounds which partially correspond to the invariants used in the sound corpus. This study also confirms that vocal imitations reveal how these invari-ants are transmitted through our perception and offers promising perspectives on auditory investigations.

International audience; This study investigates whether real-time auditory feedback has a direct behavioural or perceptual effect on novices performing a golf putting task with limited visual feedback. Due to its significant role in the success of a putt, club head speed was selected as the parameter for sonification. Different combinations of synthesisers, timbral modulations, scales, and mappings were developed to examine whether particular sound classes influenced performance. When compared to trials with static pink noise, we found that, despite their vision being limited at impact, participants were able to use different types of sonification to significantly reduce variability in their distance from the target and ball location estimation. These results suggest concurrent sound can play an important role in reducing variability in behavioural performance and related perceptual estimations. In addition, we found that, when compared to trials with static pink noise, participants were able to use sonification to significantly lower their average impact velocity. In the discussion we offer some trends and observations relative to the different sound synthesis parameters and their effects on behavioural and perceptual performance.

Car manufacturers offer a wide range of secondary driving controls, such as GPS, music, or ventilation, often localized on a central touch-sensitive screen. However, operating them while driving proves to be unsafe: engaging the sense of sight for interface interaction can lead to vigilance reduction towards the driving task, which can lead to high-risk situations. In this PhD thesis, which is a part of a collaborative research project involving both the PSA Group and the PRISM laboratory, we aim to provide a gesture and sound association as an alternative to the visual solicitation. The goal is to enable blind interface interactions, allowing the driver to focus their eyes on the road. When jointly performing interface manipulations and the driving task, a multisensory solicitation can lower the driver's cognitive load, in comparison with a visual unimodal situation. For the gesture-sound association to feel more natural, a virtual object that can be handled with gestures is introduced. This object is the support for sonification strategies, constructed by analogy with sounds from our environment, which are the consequence of an action on an object .The virtual object also allows to structure different gestures around the same metaphor, or to redefine the interface's menu. The first part of this thesis deals with the development of sonification strategies, with the aim to inform users about the virtual object dynamic. Two perceptual experiments were set up, which led to the discrimination of two valuable sonification strategies. In a second part, the automotive application was addressed by designing new sound stimuli, the interface, and by studying the multisensory integration. Sounds were proposed for each of the two sonification strategies, to progress towards an in-vehicle integration. The evocations brought by the gestures and sounds association were the subject of a third perceptive blinded experiment. The concepts around the virtual object were unknown and gradually discovered by the subjects. These mental images conveyed by the sonification strategies can help users familiarize with the interface. A fourth perceptual experiment focused on the virtual object handling for first-time users, where the integration of audio-visual stimuli was studied, in the context of an interface manipulation. The experiment conditions were similar to the driver first discovering of the interface in a parked vehicle thanks to audio-visual stimuli, and then operating it through sonification strategies only. The results of this experiment lead to the design of a gestural interface, which was compared with the results obtained with a touchscreen interface in a final perceptual experiment, carried out in a driving simulator. Although the results show better performances for the tactile interface, the combination of gestures and sounds proved to be effective from the cognitive load point of view. The gesture interface can therefore offer a promising alternative or complement to tactile interfaces for a safe simultaneous use in driving condition., Les constructeurs automobiles proposent un vaste éventail de fonctions secondaires à la conduite, en relation avec le GPS, la musique, ou encore la ventilation. L'ensemble de ces fonctions est centralisé sur un écran accessible au centre de l'habitacle, équipé d'une dalle tactile dans nombre de véhicules récents. Cependant, leur manipulation en conduite peut se révéler périlleuse : la sollicitation de la modalité visuelle pour interagir avec l'interface peut entraîner une baisse de vigilance vis-à-vis de la tâche de conduite, ce qui peut mener à des situations dangereuses. Au cours de cette thèse, fruit d'une collaboration entre le Groupe PSA et le laboratoire PRISM, nous nous sommes attachés à proposer une association de gestes et de sons comme alternative à une sollicitation visuelle. Le but est de proposer des interactions réalisables en aveugle, pour permettre au conducteur de focaliser ses yeux sur la route. Pour réaliser conjointement une manipulation de l'interface et une tâche de conduite, une sollicitation multisensorielle peut en effet permettre de faire baisser la charge mentale du conducteur, en comparaison à une situation unimodale visuelle. Pour que le lien entre les gestes et les sons paraisse naturel, un objet virtuel a été introduit, manipulable grâce à des gestes. Cet objet est le support des stratégies de sonification, par analogie aux sons de notre environnement, qui sont la conséquence d'une action sur un objet. L'objet virtuel permet également de structurer différents gestes autour d'une même métaphore, ou encore de redéfinir le menu d'une interface. La première partie de cette thèse est consacrée à la mise au point de stratégies de sonification pour transmettre des informations pertinentes sur la dynamique de l'objet virtuel. Deux expériences perceptives ont été mises en place, qui ont conduit à la discrimination de deux stratégies de sonification intéressantes. Dans une deuxième partie, nous avons œuvré à la mise en situation automobile par un travail sur les stimuli sonores, sur l'interface, et par l'étude de l'intégration multisensorielle. Un design des stratégies de sonification a été proposé pour permettre de se projeter dans une utilisation en véhicule. Par la suite, les évocations provoquées par le couplage des gestes et des sons ont été au centre d'une troisième expérience perceptive. Cette étude a été effectuée en aveugle, où le concept d'objet virtuel était inconnu et découvert progressivement par les sujets. Ces images mentales véhiculées par les stratégies de sonification peuvent en effet être utiles lors de la familiarisation des utilisateurs avec l'interface. Une quatrième expérience perceptive s'est concentrée sur la prise en main de l'objet virtuel, où l'intégration des stimuli visuels et auditifs a été étudiée, dans le contexte du maniement d'une interface. Les sujets ont été placés dans des conditions similaires à la découverte de l'interface en véhicule à l'arrêt, avec des stimuli audio-visuels ; puis à son utilisation en aveugle grâce aux stratégies de sonification. Les enseignements de ces expériences ont permis de bâtir une interface gestuelle, qui a été comparée à une interface tactile dans une dernière expérience perceptive réalisée en simulateur de conduite. Bien que les résultats montrent une utilisation plus performante de l'interface tactile, l'association des gestes et des sons semble intéressante du point de vue de la charge cognitive des conducteurs. L'interface gestuelle peut donc offrir une alternative prometteuse ou un complément aux interfaces tactiles pour une utilisation simultanée à la conduite en toute sécurité.

Despite the fundamental role played by sound in multiple virtual reality contexts, few studies have explored the perception of virtual sound source motion in the acoustic space. The goal of this study was to compare the localization of virtual moving sound sources rendered with two different spatialization techniques: Vector BaseAmplitude Panning (VBAP) and fifth-order Ambisonics (HOA), both implemented in a soundproofed room and in their most basic form (basic decoding of HOA, VBAP without spread parameter). The perception of virtual sound trajectories surrounding untrained subjects (n=23) was evaluated using a new method based on a drawing-augmented multiple-choice questionnaire. In the spherical loudspeaker array used in this study, VBAP proved to be a robust spatialization technique for sound trajectory rendering in terms of trajectory recognition and height perception. In basic-decoded HOA, subjects exhibited far more disparate trajectory recognition and height perception performances but performed better in perceiving sound source movement homogeneity.

International audience; It has long been suggested that sound plays a role in the postural control process. Few studies however have explored sound and posture interactions. The present paper focuses on the specific impact of audition on posture, seeking to determine the attributes of sound that may be useful for postural purposes. We investigated the postural sway of young, healthy blindfolded subjects in two experiments involving different static auditory environments. In the first experiment, we compared effect on sway in a simple environment built from three static sound sources in two different rooms: a normal vs. an anechoic room. In the second experiment, the same auditory environment was enriched in various ways, including the ambisonics synthesis of a immersive environment, and subjects stood on two different surfaces: a foam vs. a normal surface. The results of both experiments suggest that the spatial cues provided by sound can be used to improve postural stability. The richer the auditory environment, the better this stabilization. We interpret these results by invoking the " spatial hearing map " theory: listeners build their own mental representation of their surrounding environment, which provides them with spatial landmarks that help them to better stabilize.

International audience; Cello bowing requires a very fine control of the musicians' gestures to ensure the quality of the perceived sound. When the interaction between the bow hair and the string is optimal, the sound is perceived as broad and round. On the other hand, when the gestural control becomes more approximate, the sound quality deteriorates and often becomes harsh, shrill, and quavering. In this study, such a timbre degradation, often described by French cellists as harshness (décharnement), is investigated from both signal and perceptual perspectives. Harsh sounds were obtained from experienced cellists subjected to a postural constraint. A signal approach based on Gabor masks enabled us to capture the main dissimilarities between round and harsh sounds. Two complementary methods perceptually validated these signal features: First, a predictive regression model of the perceived harshness was built from sound continua obtained by a morphing technique. Next, the signal structures identified by the model were validated within a perceptual timbre space, obtained by multidimensional scaling analysis on pairs of synthesized stimuli controlled in harshness. The results revealed that the perceived harshness was due to a combination between a more chaotic harmonic behavior, a formantic emergence, and a weaker attack slope.

International audience; Understanding the links between the acoustical properties of sounds produced by our actions and the properties ofthe action imagined from them is a challenge that may help to understand how our sensorimotor interaction with thesurrounding world constrains our perception and reciprocally. Here we’ll present results of recent works on theacoustic characterization of a particular category of biological movements, namely drawing movements. If we listencarefully to the friction sounds produced by someone drawing, a movement can be perceived. How do we interpretthis movement perceived from a friction sound? Is it for instance possible to recognize whether or not it is a humanmovement and can the drawn shapes be deduced from the dynamics of such sounds? To investigate thesequestions, we developed sound synthesis tools enabling the generation of virtual friction sounds which can beprecisely calibrated according to movements parameters such as the velocity. A first experiment showed that we areable to recognized biological drawing movements characterized by the 2/3 power law through kinematic relatedfriction sounds (Viviani et al., JEP:HPP 1992, Thoret et al., JEP:HPP 2014). In a second time, we showed thatkinematic related friction sounds enable the recognition of geometrical shapes and even to characterize the prototype(Rosch, 1973) of an elliptical shape. Finally, in a multimodal context, we showed that friction sounds evokingmovements may distort the visuo-motor coupling of drawing movements (Thoret et al., PLoS one, 2016). Takentogether, all these experiments reveal the role of the auditory perception in the perception and production of biologicalmovements. Moreover, it provides a new framework to investigate the relationship between sounds and movements.

International audience; Even if it has been neglected for a long time, the sound and posture domain seemed to arouse an increasing interest in recent years. In the present position paper, we propose to present an overview of our recent findings on this field and to put them in perspective with the literature. We will bring evidence to support the view that spatial cues provided by auditory information can be integrated by human for a better postural control.

International audience; In this paper, a flexible control strategy for a synthesis model dedicated to nonlinear friction phenomena is proposed. This model enables to synthesize different types of sound sources, such as creaky doors, singing glasses, squeaking wet plates or bowed strings. Based on the perceptual stance that a sound is perceived as the result of an action on an object we propose a genuine source/filter synthesis approach that enables to elude physical constraints induced by the coupling between the interacting objects. This approach makes it possible to independently control and freely combine the action and the object. Different implementations and applications related to computer animation, gesture learning for rehabilitation and expert gestures are presented at the end of this paper.

International audience; The perception and production of biological movements is characterized by the 1/3 power law, a relation linking the curvature and the velocity of an intended action. In particular, motions are perceived and reproduced distorted when their kinematics deviate from this biological law. Whereas most studies dealing with this perceptual-motor relation focused on visual or kinaesthetic modalities in a unimodal context, in this paper we show that auditory dynamics strikingly biases visuomotor processes. Biologically consistent or inconsistent circular visual motions were used in combination with circular or elliptical auditory motions. Auditory motions were synthesized friction sounds mimicking those produced by the friction of the pen on a paper when someone is drawing. Sounds were presented diotically and the auditory motion velocity was evoked through the friction sound timbre variations without any spatial cues. Remarkably, when subjects were asked to reproduce circular visual motion while listening to sounds that evoked elliptical kinematics without seeing their hand, they drew elliptical shapes. Moreover, distortion induced by inconsistent elliptical kinematics in both visual and auditory modalities added up linearly. These results bring to light the substantial role of auditory dynamics in the visuo-motor coupling in a multisensory context.

International audience; Many studies stressed that the human movement execution but also the perception of motion are constrained by specific kinematics. For instance, it has been shown that the visuo-manual tracking of a spotlight was optimal when the spotlight motion complies with biological rules such as the so-called 1/3 power law, establishing the co-variation between the velocity and the trajectory curvature of the movement. The visual or kinesthetic perception of a geometry induced by motion has also been shown to be constrained by such biological rules. In the present study, we investigated whether the geometry induced by the visuo-motor coupling of biological movements was also constrained by the 1/3 power law under visual open loop control, i.e. without visual feedback of arm displacement. We showed that when someone was asked to synchronize a drawing movement with a visual spotlight following a circular shape, the geometry of the reproduced shape was fooled by visual kinematics that did not respect the 1/3 power law. In particular, elliptical shapes were reproduced when the circle is trailed with a kinematics corresponding to an ellipse. Moreover, the distortions observed here were larger than in the perceptual tasks stressing the role of motor attractors in such a visuo-motor coupling. Finally, by investigating the direct influence of visual kinematics on the motor reproduction, our result conciliates previous knowledge on sensorimotor coupling of biological motions with external stimuli and gives evidence to the amodal encoding of biological motion.

International audience; This article aims to reveal the efficiency of sonification strategies in terms of rapidity, precision and overshooting in the case of a one-dimensional guidance task. The sonification strategies are based on the four main perceptual attributes of a sound (i.e. pitch, loudness, duration/tempo and timbre) and classified with respect to the presence or not of one or several auditory references. Perceptual evaluations are used to display the strategies in a precision/rapidity space and enable prediction of user behavior for a chosen sonification strategy. The evaluation of sonification strategies constitutes a first step toward general guidelines for sound design in interactive multimedia systems that involve guidance issues.

International audience; This article presents the design, the implementation, and the perceptual evaluation of a multichannel loudspeaker array for the creation of 3D virtual sound environments. Dedicated to perceptual and postural studies, this system consists of 42 loudspeakers equally distributed around the listener on a full sphere (3 meter diameter), allowing to synthetize sounds moving within the whole 3D space. The spatial distribution of the loudspeakers makes it possible to use two different 3D rendering approaches: a physical approach through the use of 3D Higher Order Ambisonics (HOA) method up to fifth order and a perceptual approach through the use of Vector-Based Amplitude Panning (VBAP) method. A localization experiment was carried out in order to investigate the performance of the present system in terms of localization accuracy. Furthermore, this experiment aimed to explore the perceptual impact of the rendering methods (e.g. HOA and VBAP), and to evaluate the improvement of localization performance with respect to the ambisonic order (from third to fifth order). Differences between rendering methods are investigated in terms of azimuth and elevation localization errors, and front-back and up-down confusions. Finally, virtual sound source localization is compared to real sound source localization generated by 42 loudspeakers.

International audience; Listening to an auditory scene enables us to recognize a lot of events without even having to see them. For instance, a friend can often be recognized simply from the sounds of his or her footsteps. Understanding the links between the acoustical properties of sounds and the properties of the action imagined from them is a challenge that may help to understand how our sensorimotor interaction with the surrounding world constrains our perception. In this article we’ll present results of recent works on the acoustic characterization of a particular category of biological movements, namely drawing movements. In fact, if we listen carefully to the friction sounds produced by someone drawing, a movement can be perceived through the dynamic behaviour of the sounds. How do we interpret this movement imagined from a friction sound? Is it for instance possible to recognize whether or not it is a human movement and can the drawn shapes be deduced from the dynamics of such sounds? These questions might not seem important at first sight. However, as opposed to visual or kinaesthetic stimuli, monophonic sounds have the remarkable ability to transmit dynamic information independently from any geometric or spatial cues. Hence, investigating the movements imagined by someone who is listening to such sounds gives a unique opportunity to relate the properties of percepts to possible sensorimotor constraints. Highlighting a relation between drawing movements and auditory perception might thus provide a new experimental framework to study how the sensorimotor contingencies (SMC) (O’Regan & Noë, 2001) shape our sensory processes and behaviours.