Subspace-based methods have been effectively used to estimate enhanced speech from noisy speech samples. In the traditional subspace approaches, a critical step is splitting of two invariant subspaces associated with signal and noise via subspace decomposition, which is often performed by singular-value decomposition or eigenvalue decomposition. However, these decomposition algorithms are highly sensitive to the presence of large corruptions, resulting in a large amount of residual noise within enhanced speech in low signal-to-noise ratio (SNR) situations. In this paper, a joint low-rank and sparse matrix decomposition (JLSMD) based subspace method is proposed for speech enhancement. In the proposed method, we firstly structure the corrupted data as a Toeplitz matrix and estimate its effective rank value for the underlying clean speech matrix. Then the subspace decomposition is performed by means of JLSMD, where the decomposed low-rank part corresponds to enhanced speech and the sparse part corresponds to noise signal, respectively. An extensive set of experiments have been carried out for both of white Gaussian noise and real-world noise. Experimental results show that the proposed method performs better than conventional methods in many types of strong noise conditions, in terms of yielding less residual noise and lower speech distortion.

In 2011 twelve early medieval coins found their way to the collection of the Coins, Medals and Seals Department of the Ossolineum, including nine cross pennies of the types VII (Crosier) and VIII (Hand-head), a penny of Boleslaus the Bold of the 'royal' type, and two specimens with the names of Boleslaus and St John, extremely rare and interesting, attributed to the Wrocław mint. Part of these: the two pennies with St John's name and cross pennies of type VII, may derive from a scattered hoard from the village of Kopacz, Złotoryja County, Dolnośląskie Voivodeship.