Improved Convolutive and Under-Determined Blind Audio Source Separation with MRF Smoothing

Convolutive and under-determined blind audio source separation from noisy recordings is a challenging problem. Several computational strategies have been proposed to address this problem. This study is concerned with several modifications to the expectation-minimization-based algorithm, which iteratively estimates the mixing and source parameters. This strategy assumes that any entry in each source spectrogram is modeled using superimposed Gaussian components, which are mutually and individually independent across frequency and time bins. In our approach, we resolve this issue by considering a locally smooth temporal and frequency structure in the power source spectrograms. Local smoothness is enforced by incorporating a Gibbs prior in the complete data likelihood function, which models the interactions between neighboring spectrogram bins using a Markov random field. Simulations using audio files derived from stereo audio source separation evaluation campaign 2008 demonstrate high efficiency with the proposed improvement

Blind Separation of Underdetermined Convolutive Mixtures Using Their Time–Frequency Representation

International audienceThis paper considers the blind separation of nonsta-tionary sources in the underdetermined convolutive mixture case. We introduce, two methods based on the sparsity assumption of the sources in the time-frequency (TF) domain. The first one assumes that the sources are disjoint in the TF domain; i.e. there is at most one source signal present at a given point in the TF domain. In the second method, we relax this assumption by allowing the sources to be TF-nondisjoint to a certain extent. In particular, the number of sources present (active) at a TF point should be strictly less than the number of sensors. In that case, the separation can be achieved thanks to subspace projection which allows us to identify the active sources and to estimate their corresponding time-frequency distribution (TFD) values. Another contribution of this paper is a new estimation procedure for the mixing channel in the underdetermined case. Finally, numerical performance evaluations and comparisons of the proposed methods are provided highlighting their effectiveness

Méthodes de séparation aveugle de sources pour le démélange d'images de télédétection

Nous proposons dans le cadre de cette thèse, de nouvelles méthodes de séparation aveugle de mélanges linéaires instantanés pour des applications de télédétection. La première contribution est fondée sur la combinaison de deux grandes classes de méthodes de Séparation Aveugle de Sources (SAS) : l'Analyse en Composantes Indépendantes (ACI), et la Factorisation en Matrices Non-négatives (NMF). Nous montrons comment les contraintes physiques de notre problème peuvent être utilisées pour éliminer une partie des indéterminations liées à l'ACI et fournir une première approximation des spectres de endmembers et des fractions d'abondance associées. Ces approximations sont ensuite utilisées pour initialiser un algorithme de NMF, avec pour objectif de les améliorer. Les résultats obtenus avec notre méthode sont satisfaisants en comparaison avec les méthodes de la littérature utilisées dans les tests réalisés. La deuxième méthode proposée est fondée sur la parcimonie ainsi que sur des propriétés géométriques. Nous commençons par mettre en avant quelques propriétés facilitant la présentation des hypothèses considérées dans cette méthode, puis nous mettons en lumière les grandes lignes de cette dernière qui est basée sur la détermination des zones bi-sources contenues dans une image de télédétection, ceci à l'aide d'un critère de corrélation. A partir des intersections des droites générées par ces zones bi-sources, nous détaillons le moyen d'obtention des colonnes de la matrice de mélange et enfin des sources recherchées. Les résultats obtenus, en comparaison avec plusieurs méthodes de la littérature sont très encourageants puisque nous avons obtenu les meilleures performances.Within this thesis, we propose new blind source separation (BSS) methods intended for instantaneous linear mixtures, aimed at remote sensing applications. The first contribution is based on the combination of two broad classes of BSS methods : Independent Component Analysis (ICA), and Non-negative Matrix Factorization (NMF). We show how the physical constraints of our problem can be used to eliminate some of the indeterminacies related to ICA and provide a first approximation of endmembers spectra and associated sources. These approximations are then used to initialize an NMF algorithm with the goal of improving them. The results we reached are satisfactory as compared with the classical methods used in our undertaken tests. The second proposed method is based on sparsity as well as on geometrical properties. We begin by highlighting some properties facilitating the presentation of the hypotheses considered 153 in the method. We then provide the broad lines of this approach which is based on the determination of the two-source zones that are contained in a remote sensing image, with the help of a correlation criterion. From the intersections of the lines generated by these two-source zones, we detail how to obtain the columns of the mixing matrix and the sought sources. The obtained results are quite attractive as compared with those reached by several methods from literature