Human societies share the ability to develop cultural traits and to have them evolve in various geo-cultural environments, imposing different types of constraints on cultural changes. Given the geographic spread of human societies and their vast cultural diversity, these changes vary according to the populations considered and to the nature of the observed cultural domains. Mechanisms at stake in the transformation of a cultural object are still little-known. While one can easily describe the effects of diversity and hence the results of cultural evolution at one precise moment in time, the processes put in place by human societies to culturally distinguish themselves from one another are still rarely studied. Music and language are two of the cultural domains shared by all human communities on the planet. The ngombi project proposes to study the transformation processes of musical instruments in oral tradition populations while grounding its approach on inter-disciplinary research, combining methods from social sciences and natural sciences. The aim is to understand the specific mechanisms of instruments’ transformation processes, but also to understand the impact of socio-cultural contexts on these mechanisms. This study, which claims to be exploratory, will concern more specifically Central African harps. The choice of the instrument and of the study’s perspective are due to the geo-cultural anchoring of the team members (CAR, Gabon, Congo, Uganda), and to the research orientations developed i.e. the global comprehension of creation, transformation and diffusion processes of the musical patrimonies’ elements. Central African harps that are found nowadays, and which exist in the form of historical artifacts in museums’ collections bear witness of the great diversity of their morphologic and acoustic characteristics, of their repertoires and designations. Despite this diversity, it is nonetheless possible to recognize some similarities grounded for instance on the shape of the sound box, the symbolic representation of the instrument, the designation or the associated songs’ themes. Several studies have shown that these resemblances can transcend the identity distinctive features of the populations who use them (ethnonyms, linguistic groups), as well as their geographical dispersion. One of our first hypotheses is thus that, despite the diversity observed, it is possible to reveal proto-forms (which could be compared to hypothetical “ancestors”) on which would be grounded a categorization of Central African harps through the acknowledgment of common traits. Our aim is to determine if the processes leading to harps’ diversity are concurrents of the transformation of their socio-cultural contexts of performance and/or of identity strategies at different levels. The following hypothesis is to be verified: are the harps’ transformations due to adaptations to their performative context and/or to a multiplicity of markers of identity (ethnic, linguistic, technical, symbolic, etc.)? By using objects from museum collections as well as objects studied in the field, the novelty of our approach is not only to compare objects considering organological, acoustic and linguistic domains, but also to introduce anthropological data, allowing us to take into account the various factors having an impact of the harps’ variability and diversity.

The propagation of respiratory diseases involves the expectoration of small droplets, in various manners such as speach, sneeze or cough. A single sneeeze may send droplets up to six meters. Droplets as small as 100nm may contain the SARS Cov 2 virus which has a diameter of approximately 60-140 nm. The natural history and quantitative analysis of these tiny droplets is very poorly known. While droplets of sizes larger than a few microns can in principle be observed experimentally by optical methods, the observation is not easy and the number and physical fate of droplets of small sizes is thus unknown. This motivates the study which is organized on three axes - how many droplets of each size are created in a cough or sneeze in connection with an extensive experience and an intense ongoing effort on the topic of droplet size distribution; - how do small particles diffuse/disperse in the environment (This may seem a well studied topic, but the interaction with turbulence, rheology, multicompositional systems and evaporation dynamics make it much more complex); - how do small particles of mucus liquid dry in the environment both when suspended in air and when deposited on a surface (This topic is related to that of heat and mass transfer from droplets) . The local environment of a micron size droplet in even very moderately turbulent air may be fluctuating so the rate of drying may be a characteristic of air turbulence (just as a hot wire signal) or of local fluctuations in the humidity and temperature. Starting on this basis, the project will be performed in collaboration between the Paris-SU group specialising on theoretical and numerical aspects of atomization and the Cambridge-MIT group. The groups are already involved in collaborative work on the physics of drops, and the MIT group on mathematical-statistical studies of covid transmission. The most typical mechanisms for the production of the droplet size distribution are the hole formation and the ligament breakup mechanism. Both will be reviewed together with an analysis of the ligament size distribution and a re-analysis of the experiments. For a given expectorated mass, the likely ranges of minimum and maximum droplet sizes and the corresponding numbers will be predicted from the literature and previous studies. We stress that the objective of the project is not to perform new experiments or computer simulations of the processes, but organize what is already known in a manner that allows useful quantitative predictions for epidemiologists. In particular, attention will be focused on the aerosol (diameter less than 100 microns) droplet formation mechanisms. These are - the satellite droplet mechanism which leads to the formation of approximately ten times smaller droplets than the main droplets in an atomization process. - the thin sheet/hole perforation mechanism for saliva or mucus, currently unexplored. The diffusion and dispersion of droplets in the environment is a critical process. Micron-size droplets settle to the floor in thirty minutes to eight hours in a perfectly quiet atmosphere, but the situation is much more complex whenever air turbulence, always present to some degree, is taken into account. Turbulent dispersion will considerably increase the range of droplet sizes that remain suspended in air for a long time. The humidity of the air influences the survival of the virus, by affecting its bilipidic layer envelope, thus the dynamics of vapor exchange on small droplets have relevance. As the research will considerably improve our knowledge of the aerosol and large droplet properties, it will have enormous impact on recommendations for transmission reduction. In particular, it is extremely important to exclude or confirm the existence of long distance disease transmission by areosol particles.

Audition is a key modality to understand and to interact with our spatial environment, and plays a major role in Augmented Reality (AR) applications. The HAIKUS project investigates the use of Artificial Intelligence (AI) for synthesising augmented acoustic scenes. Embedding computer-generated or pre-recorded auditory content into a user's real acoustic environment creates an engaging and interactive experience that can be applied to video games, museum guides or radio plays. Audio-signal processing tools for real-time 3D sound spatialisation and artificial reverberation are nowadays mature and can handle both multichannel loudspeaker systems and binaural rendering over headphones. However, the seamless and congruent integration of computer-generated and pre-recorded objects within a live context is still challenging. It needs the automatic adaptation of the virtual object rendering to the acoustic properties of the user’s real environment. Among the different subcategories of AI, machine learning (ML) is well suited to the audio processing in virtual and augmented reality applications. ML has shown its strong potential for solving complex acoustic problems such as sound source localisation or source separation. In the HAIKUS project, ML is applied to the identification and manipulation of the acoustic channels between the sources and the listener. The three main objectives of the project are (a) the blind estimation of room acoustic parameters and/or the room geometry from the observed reverberant audio signals originating from live sounds occurring in the room, (b) the inference of plausible rules to modify the spatialisation parameters and methods to interpolate between room impulse responses according to the movement of the listener, and (c) the blind estimation of the HRTFs of the listener from binaural signals captured in a real environment with in-ear microphones. The three objectives benefit from the mobility of the listener, which allows for gradually accumulating knowledge about the acoustic environment. The HAIKUS project brings together three research teams with complementary expertise in the fields of signal processing, machine learning, acoustics, and audio technology. The general methodology combines statistical methods, acoustic modelling, and machine learning. The division of the scientific program is structured around the three main objectives. Each objective requires the development of statistical deep regression methods in order to map audio features extracted from observed signals to the acoustic parameters we want to estimate. Each objective tackles this problem from a different perspective, i.e. with different input and output features, and different assumptions about the known and unknown variables. Learning the mapping between the observed audio features and the target acoustic parameters requires the creation of dedicated audio datasets either built from numerical modelling or from real-world recordings. The scientific results will be disseminated in publications and conferences representative of signal processing, acoustics or audio. Besides the theoretical results, practical outcomes will also comprise the development of a high-order spherical microphone array. In the spirit of open research, the generated or collected audio datasets will be made publicly available in order to serve the scientific community. Considering the increasing interest on applications of machine learning and auditory scene analysis, two workshops will be organised during the project. The workshops will address both the scientific community and companies involved in AAR research and development, and from other potential application domains such as audio/video gaming, cultural heritage, professional audio production, and broadcasting. Work dedicated to the personalisation of HRTFs using binaural recordings should lead to an original web-based solution for personalised binaural rendering accessible to any consumer.

Human communication relies primarily on acoustic propagation and radiation to achieve the transmission of information. The radiation of waves at the lips remains a poorly understood phenomenon, although it affects a large number of everyday situations. This project proposes the development of an multimodal instrumentation for the study of the radiation of the voice at different operating scales: 3D directivity, nearfield structures and resonances within the vocal tract. The proposed device must operate in situ and in operando, on unique vocal productions, without assumption of repeatability or stationarity. The project aims to combine material realization and experiments with innovative theoretical and numerical concepts such as compressed sensing, radiation modes and advanced time-frequency analysis, to ensure reasonable complexity while seeking performances comparable to the perceptual human capabilities. The fallout concerns phonetics, virtual reality, telecoms.

Granular matter and powders are widely used in the manufacturing of numerous products and in many industries. Despite this intense utilisation, their behaviour and rheological properties are still badly understood. One major difficulty is that powders and their ability to flow are strongly affected by cohesive effects. In worst cases, the flow may stop and is somehow difficult to start again. A concept of “flowability” has been introduced through different qualitative indexes to characterize the ability of powder to flow, but the flowability is not clearly related to physical and rheological properties of the powder. As a result, characterization tools available for the companies working with powders provide disparate measurements and only give qualitative information about the flow properties. Our objectives in this COPRINT proposal is twofold: 1) providing a physical understanding of the concept of flowability by studying the rheology of powders in various configurations both experimentally and numerically. 2) designing innovative tools to characterize powders for the industrial partner. The first goal will be achieved by coupling experiments on a controlled-cohesive granular material as well as on real industrial powders with numerical simulations both discrete and based on continuum modelling. In the same spirit as what has been developed the last 15 years to study dry granular materials, our study will focus on simple but physically relevant configurations like inclined planes, shear cells, rotating drums. A central question we would like to focus on, will be the response of the powder to transient flows and to perturbations, to test if the flowability concept might be related to clogging instability. The second aim of the project is to use our better knowledge of the rheology to design new tools to characterize powders in industrial environments. The design of these new tools should be simple enough to be implemented in severe industrial conditions but should also provide quantitative measurements directed related to the rheological properties of the material. Three configurations have been identified as potentially relevant: inclined plane, flow around a cylinder and rotating drums. This ambitious project of both academic and industrial interest is proposed by a consortium of 3 partners, two complementary academic laboratories (IUSTI and ?’Alembert) and an industrial partner (CREE Saint Gobain) and will take place on a long-term program of 4-years. It will gather scientific, academic and industrial skills and should extend the recent progresses on the rheology of granular matter to cohesive powders and provide new tools for an industrial usage.