Listening to features

This work explores nonparametric methods which aim at synthesizing audio from low-dimensionnal acoustic features typically used in MIR frameworks. Several issues prevent this task to be straightforwardly achieved. Such features are designed for analysis and not for synthesis, thus favoring high-level description over easily inverted acoustic representation. Whereas some previous studies already considered the problem of synthesizing audio from features such as Mel-Frequency Cepstral Coefficients, they mainly relied on the explicit formula used to compute those features in order to inverse them. Here, we instead adopt a simple blind approach, where arbitrary sets of features can be used during synthesis and where reconstruction is exemplar-based. After testing the approach on a speech synthesis from well known features problem, we apply it to the more complex task of inverting songs from the Million Song Dataset. What makes this task harder is twofold. First, that features are irregularly spaced in the temporal domain according to an onset-based segmentation. Second the exact method used to compute these features is unknown, although the features for new audio can be computed using their API as a black-box. In this paper, we detail these difficulties and present a framework to nonetheless attempting such synthesis by concatenating audio samples from a training dataset, whose features have been computed beforehand. Samples are selected at the segment level, in the feature space with a simple nearest neighbor search. Additionnal constraints can then be defined to enhance the synthesis pertinence. Preliminary experiments are presented using RWC and GTZAN audio datasets to synthesize tracks from the Million Song Dataset.Comment: Technical Repor

The Dayton Food System: Current Access to Food in Dayton and Future Possibilities

Downtown Dayton and its surrounding areas are considered to be a food desert by the USDA, which means there is limited access to healthy foods within a .5 mile radius. The implications of this include driving further for groceries or turning to convenience stores for highly processed foods. This has created health concerns for the residents of Dayton, including obesity and diabetes. The purpose of this study was to understand the food system issues, their complexity and implications, and to understand what groups are currently doing to support the food system, and what is necessary to push the issues forward and make positive progress. The research was done through interviews with the various people, groups, and organizations involved in the food system. This research will provide suggestions for further actions with the goal of making healthy, local foods accessible to all those in the area

How informative is formative assessment? Investigating the learning process of educators who adopt formative assessment as practice

Researchers of formative assessment have concluded that, when teachers practice formative assessment as a process of learning, student achievement of outcomes increases. Other researchers have explored the success rate of teachers’ professional development when they engage in a professional learning community and have concluded it offers the best results. Both have distinct yet very similar attributes that lead learners into becoming cognizant and reflective conduits for knowledge acquisition. The purpose of this study is to determine if instructors, who learn about formative assessment practice by participating in professional learning teams, would encounter a process of learning similar to learners who engage in a formative assessment environment. The investigation into current literature uncovered characteristics that were codified to elicit evidence of their learning. Using data collection tools such as transcribed conversations, journals, observation and student focus group, themes were revealed that provide evidence of similarities. For this study, nine instructors who worked in a Canadian college located in the Middle East met regularly in professional learning teams, for three consecutive semesters, to learn how to implement formative assessment practice in their classrooms. They endeavoured to adopt the strategies and techniques essential to creating a formative assessment environment for students who have culturally different backgrounds. Using an ethnographic case study approach with direct content analysis, the evidence from this study has revealed that the instructors learning behaviour in the professional learning teams is analogous to learners who engage in a formative assessment learning environment. In each environment learners collaborate, reflect and evaluate their learning. The study also revealed sharing of personal and professional experiences builds an environment of trust that nurtures and empowers those who participated helping them to learn, grow and change. It is acknowledged that the social reality of the cultural context in this study leaves replication open to varying results. Attention to the affect of student motivation on teacher learning may produce differing outcomes

Informed Source Separation from compressed mixtures using spatial wiener filter and quantization noise estimation

International audienceIn a previous work, we proposed an Informed Source Separation sys- tem based on Wiener filtering for active listening of music from un- compressed (16-bit PCM) multichannel mix signals. In the present work, the system is improved to work with (MPEG-2 AAC) com- pressed mix signals: quantization noise is estimated from the AAC bitstream at the decoder and explicitly taken into account in the source separation process. Also a direct MDCT-to-STFT transform is used to optimize the computational efficiency of the process in the STFT domain from AAC-decoded MDCT coefficients

Reference-less measurement of the transmission matrix of a highly scattering material using a DMD and phase retrieval techniques

This paper investigates experimental means of measuring the transmission matrix (TM) of a highly scattering medium, with the simplest optical setup. Spatial light modulation is performed by a digital micromirror device (DMD), allowing high rates and high pixel counts but only binary amplitude modulation. We used intensity measurement only, thus avoiding the need for a reference beam. Therefore, the phase of the TM has to be estimated through signal processing techniques of phase retrieval. Here, we compare four different phase retrieval principles on noisy experimental data. We validate our estimations of the TM on three criteria : quality of prediction, distribution of singular values, and quality of focusing. Results indicate that Bayesian phase retrieval algorithms with variational approaches provide a good tradeoff between the computational complexity and the precision of the estimates

Imaging With Nature: Compressive Imaging Using a Multiply Scattering Medium

The recent theory of compressive sensing leverages upon the structure of signals to acquire them with much fewer measurements than was previously thought necessary, and certainly well below the traditional Nyquist-Shannon sampling rate. However, most implementations developed to take advantage of this framework revolve around controlling the measurements with carefully engineered material or acquisition sequences. Instead, we use the natural randomness of wave propagation through multiply scattering media as an optimal and instantaneous compressive imaging mechanism. Waves reflected from an object are detected after propagation through a well-characterized complex medium. Each local measurement thus contains global information about the object, yielding a purely analog compressive sensing method. We experimentally demonstrate the effectiveness of the proposed approach for optical imaging by using a 300-micrometer thick layer of white paint as the compressive imaging device. Scattering media are thus promising candidates for designing efficient and compact compressive imagers.Comment: 17 pages, 8 figure

An overview of informed audio source separation

International audienceAudio source separation consists in recovering different unknown signals called sources by filtering their observed mixtures. In music processing, most mixtures are stereophonic songs and the sources are the individual signals played by the instruments, e.g. bass, vocals, guitar, etc. Source separation is often achieved through a classical generalized Wiener filtering, which is controlled by parameters such as the power spectrograms and the spatial locations of the sources. For an efficient filtering, those parameters need to be available and their estimation is the main challenge faced by separation algorithms. In the blind scenario, only the mixtures are available and performance strongly depends on the mixtures considered. In recent years, much research has focused on informed separation, which consists in using additional available information about the sources to improve the separation quality. In this paper, we review some recent trends in this direction

Principled methods for mixtures processing

This document is my thesis for getting the habilitation à diriger des recherches, which is the french diploma that is required to fully supervise Ph.D. students. It summarizes the research I did in the last 15 years and also provides the short­term research directions and applications I want to investigate. Regarding my past research, I first describe the work I did on probabilistic audio modeling, including the separation of Gaussian and α­stable stochastic processes. Then, I mention my work on deep learning applied to audio, which rapidly turned into a large effort for community service. Finally, I present my contributions in machine learning, with some works on hardware compressed sensing and probabilistic generative models.My research programme involves a theoretical part that revolves around probabilistic machine learning, and an applied part that concerns the processing of time series arising in both audio and life sciences

The Influence Of Hydrology And Climate On The Isotope Geochemistry Of Playa Carbonates: A Study From Pilot Valley, NV, USA

Carbonates often accompany lake and lake-margin deposits in both modern and ancient geological settings. If these carbonates are formed in standing water, their stable isotope values reflect the aquatic chemistry at the time of precipitation and may provide a proxy for determining regional hydrologic conditions. Carbonate rhizoliths and water samples were collected from a playa lake in eastern Nevada. Pilot Valley (rv43°N) is a closed-basin, remnant playa from the Quaternary desiccation of palaeo-Lake Bonneville. Water is added to the playa margin by free convection of dense brines to the east and forced convection of freshwater off the alluvial fan to the west. Both freshwater and saline springs dot the playa margin at the base of an alluvial fan. Water samples collected from seven springs show a range from )16 to )0Æ2& (Vienna Standard Mean Ocean Water), and are consistent with published values. The d18Ocalcite values from rhizolith samples range from )18Æ3 to )6Æ7& (Vienna Pee Dee Belemnite), and the average is )12& V-PDB (1 ) r SD 2&). With the exception of samples from Little Salt Spring, the range in the d18Ocalcite values collected from the rhizoliths confirms that they form in equilibrium with ambient water conditions on the playa. The initial geochemical conditions for the spring waters are dictated by local hydrology: freshwater springs emerge in the northern part of the basin to the east of a broad alluvial fan, and more saline springs emerge to the south where the influence of the alluvial fan diminishes. Rhizoliths are only found near the southern saline springs and their d13Ccalcite values, along with their morphology, indicate that they only form around saltgrass (Distichlis sp.). As the residence time of water on the playa increases, evaporation, temperature change and biological processes alter the aquatic chemistry and initiate calcite precipitation around the plant stems. The range in d18Ocalcite values from each location reflects environmental controls (e.g. evaporation and temperature change). These rhizoliths faithfully record ambient aquatic conditions during formation (e.g. geochemistry and water depth), but only record a partial annual signal that is constrained by saltgrass growth and the presence of standing water on the playa margin