@Article{, Title = {Estimation of acoustic reflection coefficients through pseudospectrum matching}, Author = {D. Markovic and K. Kowalczyk and F. Antonacci and C. Hofmann and A. Sarti and W. Kellermann}, Journal = {IEEE/ACM Trans. on Audio, Speech and Language Processing}, Year = {2014}, Month = {January}, Number = {1}, Pages = {1-13}, Volume = {22}, } @Conference{vid_19264, Title = {{Diffuseness-based Mixing Time Prediction using a Spherical Microphone Array}}, Author = {G\"{o}tz, Philipp and Silzle, Andreas and Kowalczyk, Konrad and Habets, Emanuel}, Year = {2014}, Month = {February}, Abstract = {The mixing time is an important parameter in the human perception of room acoustics. It is defined as the time instant of room impulse responses (RIRs) when coherent early reflections dissolve into diffuse reverberation. Most common mixing time estimation methods statistically analyze a single RIR by measuring the density of reflections or the degree of correlation of reflections. Since these methods are based on the analysis of only one RIR, they do not take the spatial properties of the sound field into account. In this work, RIRs measured with a spherical microphone array are usedto compute the diffuseness of the reflections over a short period of time, from which the mixing time can be inferred.Using specific parameter settings, the presented method is shown to correlate well with existing mixing time prediction methods.}, Language = {englisch}, } @InProceedings{, Title = {Extended Kalman filter with probabilistic data association for multiple non-concurrent speaker localization in reverberant environments}, Author = {S. Chakrabarty and K. Kowalczyk and M. Taseska and {E.A.P.} Habets}, Booktitle = {Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (ICASSP)}, Year = {2014}, Address = {Florence, Italy}, Month = {May}, } @Article{, Title = {Room geometry interference based on spherical microphone array eigenbeam processing}, Author = {E. Mabande and K. Kowalczyk and H. Sun and W. Kellermann}, Journal = {J. Acoustical Society of America (JASA)}, Year = {2013}, Month = {October}, Number = {4}, Pages = {2773-2789}, Volume = {134}, } @Conference{vid_18432, Title = {{Sound acquisition in noisy and reverberant environments using virtual microphones }}, Author = {Kowalczyk, Konrad and Thiergart, Oliver and Craciun, Alexandra and Habets, Emanuel A. P.}, Booktitle = {Proceedings, IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA 2013)}, Year = {2013}, Month = {October}, Pages = {1--4}, Abstract = {In hands-free communication applications, the main goal is to capture desired sounds, while reducing noise and interfering sounds. However, for natural-sounding telepresence systems, the spatial sound image should also be preserved. Using a recently proposed method for generating the signal of a virtual microphone (VM), one can recreate the sound image from an arbitrary point of view in the sound scene (e.g., close to a desired speaker), while being able to place the physical microphones outside the sound scene. In this paper, we present a method for synthesizing a VM signal in noisy and reverberant environments, where the estimation of the required direct and diffuse sound components is performed using two multichannel linear filters. The direct sound component is estimated using a multichannel Wiener filter, while the diffuse sound component is estimated using a linearly constrained minimum variance filter followed by a single-channel Wiener filter. Simulations in a noisy and reverberant environment show the applicability of the proposed method for sound acquisition in a scenario in which two microphone arrays are installed in a large TV.}, ISBN = {ISSN: 1931-1168 }, Language = {englisch}, Location = {New Paltz, New York}, Url = {http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6701869&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel7%2F6689475%2F6701802%2F06701869.pdf%3Farnumber%3D6701869} } @InProceedings{, Title = {Sound acquisition in noisy and reverberant environments using virtual microphones}, Author = {K. Kowalczyk and O. Thiergart and A. Craciun and E.A.P. Habets}, Booktitle = {Proc. IEEE Workshop on Applications of Sign. Process. to Audio and Acoustics (WASPAA)}, Year = {2013}, Address = {New Paltz, NY}, Month = {October}, } @Article{vid_18430, Title = {{Blind System Identification Using Sparse Learning}}, Author = {Kowalczyk, Konrad and Habets, Emanuël A. P. and Kellermann, Walter (University of Erlangen-Nuremberg) and Naylor, Patrick A. (Imperial College London)}, Journal = {IEEE Signal Processing Letters}, Year = {2013}, Month = {July}, Number = {VOL. 20, N0. 7, JULY 2013}, Pages = {653--656}, Abstract = {Localization of early room reflections can be achieved by estimating the time-differences-of-arrival (TDOAs) of reflectedwaves between elements of a microphone array. For an unknownsource, we propose to apply sparse blind system identification(BSI) methods to identify the acoustic impulse responses, fromwhich the TDOAs of temporally sparse reflections are estimated.The proposed time- and frequency -domain adaptive algorithmsbased on crossrelation formulation are regularized by incorporating an l1-norm sparseness constraint, which is realized using asplit Bregman method. These algorithms are shown to outperformstandard crossrelation-based BSI techniques when estimatingections in the presence of background noise.}, Editor = {IEEE}, ISBN = {ISSN: 1070-9908}, Language = {englisch}, } @InProceedings{vid_18431, Title = {{Generating Virtual Microphone Signals in Noisy Environments}}, Author = {Kowalczyk, Konrad and Craciun, Alexandra and Habets, Emanuël A. P.}, Booktitle = {Proceedings, 21st European Signal Processing Conference (EUSIPCO2013)}, Year = {2013}, Month = {September}, Abstract = {Spatial sound acquisition methods typically capture the soundscene with reference to the position of the recording device.Using a recently proposed virtual microphone (VM) technique,the position and characteristics of the recording device(such as the directivity response and orientation) can bemodified. This technique relies on synthesizing a VM signalat an arbitrary position, which sounds perceptually similarto the signal that would be recorded with a physical microphoneplaced at the same location. In this paper, we presenta method to generate a VM signal in the presence of noise.Noise reduction is accomplished using a parametric multichannelWiener filter, where a trade-off parameter is appliedin order to achieve a constant residual noise level in the generatedVM signal, irrespective of the VM position. The simulatedexperiments show the applicability of the method forsignal extraction in the presence of additive noise.}, Language = {englisch}, Location = {Marrakesh}, } @Article{, Title = {Localization of distinct reflections in rooms using spherical microphone array eigenbeam processing}, Author = {H. Sun and E. Mabande and K. Kowalczyk and W. Kellermann}, Journal = {J. Acoustical Society of America (JASA)}, Year = {2012}, Month = {April}, Number = {4}, Pages = {2828-2840}, Volume = {131}, } @InProceedings{, Title = {Reflection coefficient estimation by pseudospectrum matching}, Author = {D. Markovic and C. Hofmann and F. Antonacci and K. Kowalczyk and A. Sarti and W. Kellermann}, Booktitle = {Proc. Int. Workshop on Acoustic Sign. Enhancement (IWAENC)}, Year = {2012}, Address = {Aachen, Germany}, Month = {September}, Pages = {181-184}, } @Article{, Title = {Formulation and analysis of frequency-dependent boundaries in finite-difference simulation with compact explicit schemes}, Author = {M. van Walstijn and K. Kowalczyk}, Journal = {Proc. Forum Acusticum}, Year = {2011}, Month = {June/July}, } @InProceedings{, Title = {Joint DOA and TDOA estimation for 3D localization of reflective surfaces using eigenbeam MVDR and spherical microphone arrays}, Author = {H. Sun and E. Mabande and K. Kowalczyk and W. Kellermann}, Booktitle = {Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (ICASSP)}, Year = {2011}, Month = {May}, } @Article{, Title = {Comparison of subspace-based and steered beamformer-based reflection localization methods}, Author = {E. Mabande and H. Sun and K. Kowalczyk and W. Kellermann}, Journal = {Proc. European Signal Process. Conf. (EUSIPCO)}, Year = {2011}, Month = {August}, } @InProceedings{, Title = {On 2D localization of reflectors using robust beamforming techniques}, Author = {E. Mabande and H. Sun and K. Kowalczyk and W. Kellermann}, Booktitle = {Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (ICASSP)}, Year = {2011}, Month = {May}, Pages = {153-156}, } @Article{, Title = {A phase grating approach to modeling surface diffusion in FDTD room acoustics simulations}, Author = {K. Kowalczyk and M. van Walstijn and D.T. Murphy}, Journal = {IEEE Trans. on Audio, Speech and Language Processing}, Year = {2011}, Month = {March}, Number = {3}, Pages = {528-537}, Volume = {19}, } @Article{, Title = {Room acoustics simulation using 3-D compact explicit FDTD schemes}, Author = {K. Kowalczyk and M. van Walstijn}, Journal = {IEEE Trans. on Audio, Speech and Language Processing}, Year = {2011}, Month = {January}, Number = {1}, Pages = {34-46}, Volume = {19}, } @Book{, Title = {Boundary and medium modelling using compact finite difference schemes in simulations of room acoustics for audio and architectural design applications}, Author = {K. Kowalczyk}, Publisher = {Verlag Dr. Hut}, Year = {2011}, Address = {München, Germany}, } @Article{, Title = {The SCENIC project: space-time audio processing for environment-aware acoustic sensing and rendering}, Author = {P. Annibale and F. Antonacci and P. Bestagini and A. Brutti and A. Canclini and L. Cristoforetti and E. Habets and J. Filos and W. Kellermann and K. Kowalczyk and A. Lombard and E. Mabande and D. Markovic and P. Naylor and M. Omologo and R. Rabenstein and A. Sarti and P. Svaizer and M. Thomas}, Journal = {Proc. 131st Audio Eng. Soc. Conv.}, Year = {2011}, Month = {October}, } @InProceedings{, Title = {A comparison of nonstaggered compact FDTD schemes for the 3D wave equation}, Author = {K. Kowalczyk and M. van Walstijn}, Booktitle = {Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (ICASSP)}, Year = {2010}, Address = {Dallas, TX}, Month = {March}, Pages = {197-200}, } @Article{, Title = {Wideband and isotropic 2D room acoustics simulation with interpolated FDTD schemes}, Author = {K. Kowalczyk and M. van Walstijn}, Journal = {IEEE Trans. on Audio, Speech and Language Processing}, Year = {2010}, Month = {January}, Number = {1}, Pages = {78-89}, Volume = {18}, } @InProceedings{, Title = {On the numerical solution of the 2D wave equation with compact FDTD schemes}, Author = {M. van Walstijn and K. Kowalczyk}, Booktitle = {Int. Conf. on Digital Audio Effects (DAFx)}, Year = {2008}, Address = {Espoo, Finland}, Month = {September}, Pages = {205-212}, } @InProceedings{, Title = {Modeling frequency-dependent boundaries as digital impedance filters in FDTD and K-DWM room acoustics simulations}, Author = {K. Kowalczyk and M. van Walstijn}, Booktitle = {124th Convention of the Audio Eng. Soc.}, Year = {2008}, Address = {Amsterdam, The Netherlands}, Month = {May}, } @InProceedings{, Title = {Virtual room acoustics using finite difference methods. How to model and analyze frequency-dependent boundaries?}, Author = {K. Kowalczyk and M. van Walstijn}, Booktitle = {Proc. IEEE Int. Symp. on Communications, Control and Signal Process. (ISCCSP)}, Year = {2008}, Address = {St. Julians, Malta}, Month = {March}, Pages = {1504-1509}, } @Article{, Title = {Formulation of a locally reacting wall in FDTD/K-DWM modeling of acoustic spaces}, Author = {K. Kowalczyk and M. van Walstijn}, Journal = {Acta Acustica united with Acustica, special issue on Virtual Acoustics}, Year = {2008}, Month = {November/December}, Number = {6}, Pages = {891-906}, Volume = {94}, } @Article{, Title = {Modeling frequency-dependent boundaries as digital impedance filters in FDTD and K-DWM room acoustics simulations}, Author = {K. Kowalczyk and M. van Walstijn}, Journal = {J. Audio Engineering Society}, Year = {2008}, Month = {July/August}, Number = {7/8}, Pages = {569-583}, Volume = {56}, } @phdthesis{, Title = {Boundary and medium modelling using compact finite difference schemes in simulations of room acoustics for audio and architectural design applications}, Author = {K. Kowalczyk}, School = {Queen’s University of Belfast}, Year = {2008}, Address = {UK}, Month = {December}, } @InProceedings{, Title = {Formulation of a locally reacting wall in finite difference modeling of acoustic spaces}, Author = {K. Kowalczyk and M. van Walstijn}, Booktitle = {Int. Symp. on Room Acoustics (ISRA)}, Year = {2007}, Address = {Seville, Spain}, Month = {September}, } @InProceedings{, Title = {On-line simulation of 2D resonators with reduced dispersion error using compact implicit finite difference schemes}, Author = {K. Kowalczyk and M. van Walstijn}, Booktitle = {Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (ICASSP)}, Year = {2007}, Address = {Honolulu, Hawaii}, Month = {April}, Pages = {285-288}, }