Convolutive Sparse Coding of Audio Spectrograms

where sn,t is the amount of contribution of the n basis function in the t observation. There are methods which use fixed basis functions, but recently, many algorithms for the estimation of adaptive representations have been proposed, and they have been successfully used in several applications. For example, independent component analysis (ICA) estimates the basis functions by finding a decomposition in which the gains of each basis function are statistically independent from each other. Other criteria are, for example, sparseness and non-negativity of sn,t.