dr hab. inż. Konrad Kowalczyk, prof. AGH

Head of the Group - Associate Professor

Contact details:
office: C2 Building, Room 418
phone: +48 12-617-36-39
email: konrad.kowalczyk@agh.edu.pl

Bio

Konrad Kowalczyk received the B.Eng. and M.Sc. degrees in electronics and telecommunications from AGH University of Science and Technology, Krakow, Poland, in 2005, the Ph.D. degree in electronics from the School of Electronics, Electrical Engineering and Computer Science, Queen’s University, Belfast, U.K., in 2009, and the Habilitation (D.Sc.) degree in information and communication technology (ICT) from AGH University of Science and Technology in Krakow, in 2020. During his doctoral studies on numerical modelling of room acoustics at Queen’s University, he was associated with the Sonic Arts Research Centre (SARC). He was a Visiting Ph.D. Student at the Center for Computer Research in Music and Acoustics (CCRMA), Stanford University, in 2007 and at the Audio Lab, University of York, U.K., in 2008. From 2009 until 2011, he was a Postdoctoral Research Fellow at the Chair of Multimedia Communications and Signal Processing (LMS), University of Erlangen-Nuremberg, Germany, where he worked on acoustic scene analysis using microphone arrays. From 2012 until 2014 he was with Audio and Multimedia Division of Fraunhofer Institute for Integrated Circuits IIS and the International Audio Laboratories Erlangen as an Associate Researcher for communication acoustics and spatial audio processing. In 2015 he joined the Faculty of Computer Science, Electronics and Telecommunications, AGH University of Science and Technology in Krakow. Since 2020 he holds a position of an Associate Professor and heads AGH’s Signal Processing Group.

Konrad Kowalczyk completed postgraduate training in science management and commercialization at the University of Cambridge and the University of Oxford, U.K., in 2015, as a laureate of the Top 500 Innovators programme. He was a finalist of the IEEE Best Student Paper Contest at the ICASSP conference held in Hawaii in 2007, a winner of the AES Student Technical Paper Award at the AES convention held in Amsterdam in 2008, and a coauthor of a paper winning the Best Student Paper Award at IWAENC conference held in Antibes, France in 2014. In 2016 and 2019 he received the best paper awards at IEEE SPA conferences held in Poznan. He also received the Stanislaw Staszic Medal for the best graduate of AGH in 2005, and in 2016 he received a scholarship of the Polish Ministry of Science and Higher Education (MNiSW) for Distinguished Young Scientists. In 2020 he received Prime Minister Award for outstanding scientific achievements leading to the habilitation degree in category science and engineering (best habilitation from all technical universities in Poland in 2020). He has chaired sessions at European Sign. Process. Conf. (EUSIPCO) and IEEE Multimedia and Sign. Process. Works. (IEEE MMSP). He was a Guest Editor for EURASIP Journal on Audio, Speech, and Music Processing special issue on “Data-based spatial audio processing”. Currently he serves as an Associate Editor for IEEE Signal Processing Letters.


Research interests

  • speech and audio signal processing
  • machine learning, deep neural networks (DNN), artificial intelligence (AI)
  • array signal processing: beamforming, adaptive multichannel filtering
  • speech enhancement: dereverberation, noise reduction, source separation
  • distributed signal processing: self-localization, synchronization, signal enhancement
  • speech processing: speaker recognition, diarization, automatic speech recognition
  • sound field analysis: source localization, acoustic parameter inference
  • virtual acoustics: room acoustic simulations, in-car sound reproduction
  • acoustic event detection and classification
  • spatial audio acquisition and rendering over loudspeakers and headphones

Research projects

Konrad Kowalczyk is currently the Principle Investigator in the following research projects:
1. “Audio Processing using Distributed Acoustic Sensors (APDAS)”, 2018-2023, Program First TEAM, Foundation for Polish Science (FNP)
2. “Analiza zastosowania uczenia maszynowego w przestrzennym przetwarzaniu sygnałów dźwiękowych (Machine learning for spatial sound processing)”, 2019-2022, Program OPUS, National Science Center (NCN)

Main past research projects:
1. “Analiza możliwości wykorzystania akustyki pomieszczeń w celu poprawy jakości ekstrakcji sygnałów mowy (Analysis of using room acoustics information for speech signal extraction)”, 2015-2017, Program FUGA, National Science Center (NCN)
2. “Video COmmunication for NEtworked CommuniTies (VCONECT)”, 2012 -2014, EU FP7 Information and Communication Technologies (ICT), Fraunhofer Institute for Integrated Circuits IIS, Erlangen, Germany
3. “Self-Configuring ENvironment-aware Intelligent aCoustic sensing”, 2009-2012, EU FP7 Future and Emerging Technologies (FET), Friedrich-Alexander University of Erlangen-Nuremberg, Germany
4. “Numerical Modelling of Acoustic Spaces for Auralization and Acoustic Prediction”, 2005 – 2009, EU ESF Program, Queen’s University, Belfast, UK


Teaching

I am a supervisor of Ph.D., M.Sc., B.Eng. theses work and am running lectures for the following courses:

  • Signal Processing (B.Eng. level)
  • Digital Signal Processing (B.Eng. level)
  • Advanced Techniques in Signal Processing (M.Sc. level)
  • Statistical Signal Processing in Audio and Speech Applications (Doctoral School)

Main publications

Journal articles:
[J17] M. Cobos, J. Ahrens, K. Kowalczyk, and A. Politis, “An overview of machine learning and other data-based methods for spatial audio capture, processing, and reproduction,” EURASIP Journal on Audio, Speech, and Music Processing, no. 10, pp. 1-21, 2022.
[J16] M. Cobos, J. Ahrens, K. Kowalczyk, and A. Politis, “Data-based spatial audio processing,” EURASIP Journal on Audio, Speech, and Music Processing, no. 13, 2022.
[J15] M. Witkowski and K. Kowalczyk, “Split Bregman Approach to Linear Prediction Based Dereverberation With Enforced Speech Sparsity,” in IEEE Signal Processing Letters, vol. 28, pp. 942-946, 2021.
[J14] K. Kowalczyk, “Raking early reflection signals for late reverberation and noise reduction,” in Journal of the Acoustical Society of America (JASA), vol. 145, no. 3, pp. EL257-EL263, 2019.
[J13] S. Woźniak and K. Kowalczyk, “Passive Joint Localization and Synchronization of Distributed Microphone Arrays,” in IEEE Signal Processing Letters, vol. 26, no. 2, pp. 292-296, Feb. 2019.
[J12] J. Sheaffer, M. van Walstijn, B. Rafaely, and K. Kowalczyk, “Binaural reproduction of finite difference simulations using spherical array processing,” IEEE/ACM Trans. on Audio, Speech and Language Processing, vol. 23, No. 12, pp. 2125-2135, Dec. 2015.
[J11] K. Kowalczyk, O. Thiergart, M. Taseska, G. Del Galdo, and V. Pulkki, E.A.P. Habets, “Parametric spatial sound processing: a flexible and efficient solution to sound scene acquisition, modification and reproduction,” IEEE Signal Processing Magazine, vol. 32, No. 2, pp. 31-42, Mar. 2015.
[J10] P. Götz, K. Kowalczyk, A. Silzle, and E.A.P. Habets, “Mixing time prediction using spherical microphone arrays,” J. Acoustical Society of America (JASA), vol. 137, No. 2, pp. EL206-212, Feb. 2015.
[J9] D. Markovic, K. Kowalczyk, F. Antonacci, C. Hofmann, A. Sarti, and W. Kellermann, “Estimation of acoustic reflection coefficients through pseudospectrum matching,” IEEE/ACM Trans. on Audio, Speech and Language Processing, vol. 22, No. 1, pp. 1-13, Jan. 2014.
[J8] E. Mabande, K. Kowalczyk, H. Sun, and W. Kellermann, “Room geometry interference based on spherical microphone array eigenbeam processing,” J. Acoustical Society of America (JASA), vol. 134, No. 4, pp. 2773-2789, Oct. 2013.
[J7] K. Kowalczyk, E.A.P. Habets, W. Kellermann, and P.A. Naylor, “Blind system identification using sparse learning for TDOA estimation of room reflections,” IEEE Signal Processing Letters, vol. 20, No. 7, pp. 653-656, Jul. 2013.
[J6] H. Sun, E. Mabande, K. Kowalczyk, and W. Kellermann, “Localization of distinct reflections in rooms using spherical microphone array eigenbeam processing,” J. Acoustical Society of America (JASA), vol. 131, No. 4, pp. 2828-2840, Apr. 2012.
[J5] K. Kowalczyk and M. van Walstijn, “Room acoustics simulation using 3-D compact explicit FDTD schemes,” IEEE Trans. on Audio, Speech and Language Processing, vol. 19, No. 1, pp. 34-46, Jan. 2011.
[J4] K. Kowalczyk, M. van Walstijn, and D.T. Murphy, “A phase grating approach to modeling surface diffusion in FDTD room acoustics simulations,” IEEE Trans. on Audio, Speech and Language Processing, vol. 19, No. 3, pp. 528-537, Mar. 2011.
[J3] K. Kowalczyk and M. van Walstijn, “Wideband and isotropic 2D room acoustics simulation with interpolated FDTD schemes,” IEEE Trans. on Audio, Speech and Language Processing, vol. 18, No. 1, pp. 78-89, Jan. 2010.
[J2] K. Kowalczyk and M. van Walstijn, “Formulation of a locally reacting wall in FDTD/K-DWM modeling of acoustic spaces,” Acta Acustica united with Acustica, special issue on Virtual Acoustics, vol. 94, No. 6, pp. 891-906, Nov./Dec. 2008.
[J1] K. Kowalczyk and M. van Walstijn, “Modeling frequency-dependent boundaries as digital impedance filters in FDTD and K-DWM room acoustics simulations,” J. Audio Engineering Society, vol. 56, No. 7/8, pp. 569-583, Jul./Aug. 2008.

Books:
[B1] K. Kowalczyk, “Boundary and medium modelling using compact finite difference schemes in simulations of room acoustics for audio and architectural design applications,”, Verlag Dr. Hut, München, Germany, 2011. (ISBN: 978-3-8439-0273-1)

Patents:
[P2] E.A.P. Habets, O. Thiergart, K. Kowalczyk, “System, apparatus and method for consistent scene reproduction based on informed spatial filtering”, Patent US 9936323 B2 (granted in USA on 03.04.2018), Patent 6466968 (granted in Japan on 18.01.2019), Patent CN 106664501 B (granted in China on 15.02.2019)
[P1] E.A.P. Habets, O. Thiergart, and K. Kowalczyk, “System, apparatus and method for consistent scene reproduction based on adaptive functions”, Patent US 10015613 B2 (granted in USA on 03.07.2018), Patent RU 2663343 C2 (granted in Russia on 03.08.2018), Patent 6466969 (granted in Japan on 18.01.2019)

Conference papers:
[C48] J. Bartolewska, S. Kacprzak, and K. Kowalczyk, “Refining DNN-based Mask Estimation using CGMM-based EM Algorithm for Multi-channel Noise Reduction”, accepted for Annual Conf. Int. Speech Communication Association (INTERSPEECH), Incheon, Korea, 2022.
[C47] M. Fraś, M. Witkowski, and K. Kowalczyk, “Convolutive Weighted Multichannel Wiener Filter Front-end for Distant Automatic Speech Recognition in Reverberant Multispeaker Scenarios”, accepted for Annual Conf. Int. Speech Communication Association (INTERSPEECH), Incheon, Korea, 2022.
[C46] M. Rybicka, J. Villalba, N. Dehak, and K. Kowalczyk, “End-to-End Neural Speaker Diarization with an Iterative Refinement of Non-Autoregressive Attention-based Attractors“, accepted for Annual Conf. Int. Speech Communication Association (INTERSPEECH), Incheon, Korea, 2022.
[C45] M. Guzik and K. Kowalczyk , “NTF of Spectral and Spatial Features for Tracking and Separation of Moving Sound Sources in Spherical Harmonic Domain”, accepted for Annual Conf. Int. Speech Communication Association (INTERSPEECH), Incheon, Korea, 2022.
[C44] S. Kacprzak, M. Rybicka, and K. Kowalczyk, “Spoken Language Recognition with Cluster-based Modeling,” Proc. IEEE Int. Conf. on Acoustics, Speech and Sign. Process. (IEEE ICASSP), Singapore, pp. 6867-6871, 2022.
[C43] M. Guzik and K. Kowalczyk, “Wishart Localization Prior on Spatial Covariance Matrix in Ambisonic Source Separation using Non-negative Tensor Factorization,” Proc. IEEE Int. Conf. on Acoustics, Speech and Sign. Process. (IEEE ICASSP) , Singapore, pp. 446-450, 2022.
[C42] M. Fraś, M. Witkowski and K. Kowalczyk, “Convolutive Weighted Multichannel Wiener Filter Front-end for Distant Automatic Speech Recognition in Reverberant Multispeaker Scenarios,” Proc. IEEE Int. Conf. on Acoustics, Speech and Sign. Process. (IEEE ICASSP) , Singapore, pp. 286-290, 2022.
[C41] J. Bartolewska and K. Kowalczyk, “Frame-based Maximum a Posteriori Estimation of Second-Order Statistics for Multichannel Speech Enhancement in Presence of Noise,” Proc. IEEE Int. Work. Multimedia Sign. Processing (IEEE MMSP), Tampere, Finland, pp. 1-6, 2021.
[C40] M. Guzik, M. Fraś and K. Kowalczyk, “Incorporation of Localization Information for Sound Source Separation in Spherical Harmonic Domain,” Proc.  IEEE Int. Work. Multimedia Sign. Processing (IEEE MMSP), Tampere, Finland, pp. 1-6, 2021.
[C39] S. Kacprzak and K. Kowalczyk, “Adversarial Domain Adaptation with Paired Examples for Acoustic Scene Classification on Different Recording Devices,” Proc. European Sign. Process. Conf. (EUSIPCO), Dublin, Ireland, pp. 1030-1034, 2021.
[C38] M. Witkowski, M. Rybicka and K. Kowalczyk, “Sparse Linear Prediction-based Dereverberation for Signal Enhancement in Distant Speaker Verification,” Proc. European Sign. Process. Conf. (EUSIPCO), Dublin, Ireland, pp. 461-465, 2021.
[C37] D. Krause, A. Politis and K. Kowalczyk, “Data Diversity for Improving DNN-based Localization of Concurrent Sound Events,” Proc. European Sign. Process. Conf. (EUSIPCO), Dublin, Ireland, pp. 236-240, 2021.
[C36] M. Fraś, M. Witkowski, and K. Kowalczyk, “Combating Reverberation in NTF-Based Speech Separation Using a Sub-Source Weighted Multichannel Wiener Filter and Linear Prediction,” Proc. Annual Conf. Int. Speech Communication Association (INTERSPEECH), Brno, Czech Republic, pp. 3895-3899, 2021.
[C35] M. Rybicka, J. Villalba, P. Żelasko, N. Dehak and Kowalczyk, “Spine2Net: SpineNet with Res2Net and Time-Squeeze-and-Excitation Blocks for Speaker Recognition,” Proc. Annual Conf. Int. Speech Communication Association (INTERSPEECH), Brno, Czech Republic, pp. 496-500, 2021.
[C34] M. Fraś and K. Kowalczyk, “Maximum a posteriori estimator for convolutive sound source separation with sub-source based NTF model and the localization probabilistic prior on the mixing matrix,” Proc. IEEE Int. Conf. on Acoustics, Speech and Sign. Process. (IEEE ICASSP) , Vancouver, Canada, pp. 526-530, 2021.
[C33] D. Krause, A. Politis and K. Kowalczyk, “Comparison of Convolution Types in CNN-based Feature Extraction for Sound Source Localization,” Proc. European Sign. Process. Conf. (EUSIPCO), Amsterdam, The Netherlands, pp. 820-824, 2021.
[C32] D. Krause, A. Politis and K. Kowalczyk, “Feature Overview for Joint Modeling of Sound Event Detection and Localization Using a Microphone Array,” Proc. European Sign. Process. Conf. (EUSIPCO), Amsterdam, The Netherlands, pp. 31-35, 2021.
[C31] M. Rybicka and K. Kowalczyk, “On Parameter Adaptation in Softmax-based Cross-Entropy Loss for Improved Convergence Speed and Accuracy in DNN-based Speaker Recognition,” Proc. Annual Conf. Int. Speech Communication Association (INTERSPEECH), Shanghai, China, pp. 3805-3809, 2020.
[C30] J. Bartolewska and K. Kowalczyk, “Distributed Multiarray Noise Reduction With Online Estimation Of Masks And Spatial Filters,” Proc. IEEE Sensor Array and Multichannel Sign. Process. Works. (IEEE SAM), Hangzhou, China, 2020.
[C29] S. Woźniak and K. Kowalczyk, “Exploiting Rays in Blind Localization of Distributed Sensor Arrays,” Proc. IEEE Int. Conf. on Acoustics, Speech and Sign. Process. (IEEE ICASSP), Barcelona, Spain, pp. 221-225, 2020.
[C28] M. Witkowski, M. Rybicka and K. Kowalczyk, “Speaker Recognition from Distance Using X-Vectors with Reverberation-Robust Features,” Proc. IEEE Sign. Process.: Algorithms, Architectures, Arrangements, and Applications (IEEE SPA), Poznan, Poland, pp. 235-240, 2019.
[C27] K. Kowalczyk, “Multichannel Wiener Filter with Early Reflection Raking for Automatic Speech Recognition in Presence of Reverberation,”  Proc. IEEE Sign. Process.: Algorithms, Architectures, Arrangements, and Applications (IEEE SPA), Poznan, Poland, pp. 197-201, 2019. Best Paper Award
[C26] S. Woźniak, K. Kowalczyk and M. Cobos, “Self-Localization of Distributed Microphone Arrays Using Directional Statistics with DoA Estimation Reliability,” Proc. European Sign. Process. Conf. (EUSIPCO), A Coruna, Spain, 2019.
[C25] D. Krause and K. Kowalczyk, “Multichannel fusion and audio-based features for acoustic event classification,” Proc. 145th Audio Engineering Society Convention, New York, NY, pp. 1-8, Paper: 10103, Oct. 2018.
[C24] K. Kowalczyk, S. Kacprzak and M. Ziółko, “On the extraction of early reflection signals for automatic speech recognition,”  Proc. IEEE Int. Conf. on Sign. and Image Process. (IEEE ICSIP), Singapore, pp. 351-355, 2017.
[C23] M. Witkowski, S. Kacprzak, P. Żelasko, K. Kowalczyk and J. Galka, “Audio Replay Attack Detection Using High-Frequency Features”,  Proc. Annual Conf. Int. Speech Communication Association (INTERSPEECH), Stockholm, Sweden, pp. 27-31, 2017.
[C22] K. Kowalczyk, S. Woźniak, T. Chyrowicz and R. Rumian, “Embedded system for acquisition and enhancement of audio signals,”  Proc. IEEE Sign. Process.: Algorithms, Architectures, Arrangements, and Applications (IEEE SPA), Poznan, pp. 68-71, 2016. Best Paper Award
[C21] S. Braun, K. Kowalczyk, and E.A.P. Habets, “ Residual noise control using a parametric multichannel Wiener filter,” Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (IEEE ICASSP), pp. 360-364, Brisbane, Australia, Apr. 2015.
[C20] O. Thiergart, K. Kowalczyk, and E.A.P. Habets, “An acoustical zoom based on informed spatial filtering,” Proc. Int. Workshop on Acoustic Sign. Enhancement (IWAENC), Antibes – Juan les Pins, France, Sep. 2014. Coauthor of the paper that won the Best Student Paper Award
[C19] K. Kowalczyk, A. Craciun, C. Dachmann, and E.A.P. Habets, “Spatial perception of virtual X-Y recordings,” Proc. Int. Works. on Acoustic Sign. Enhancement (IWAENC), Antibes – Juan les Pins, France, Sep. 2014.
[C18] J. Sheaffer, M. van Walstijn, B. Rafaely, and K. Kowalczyk, “A spherical array approach for simulation of binaural impulse responses using the finite difference time domain method,” Proc. Forum Acusticum, Krakow, Poland, Sep. 2014.
[C17] S. Chakrabarty, K. Kowalczyk, M. Taseska, and E.A.P. Habets, “Extended Kalmann filter with probabilistic data association for multiple non-concurrent speaker localization in reverberant environments,” Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (IEEE ICASSP), pp.7445-7449, Florence, Italy, May 2014.
[C16] P. Götz, A. Silzle, K. Kowalczyk, and E.A.P. Habets, “Diffuseness-based mixing time prediction using a spherical microphone array,” Int. Conf. Spatial Audio (ICSA), Erlangen, Germany, Feb. 2014.
[C15] K. Kowalczyk, O. Thiergart, A. Craciun, E.A.P. Habets, “Sound acquisition in noisy and reverberant environments using virtual microphones,” Proc. IEEE Workshop on Applications of Sign. Process. to Audio and Acoustics (IEEE WASPAA), New Paltz, NY, Oct. 2013.
[C14] K. Kowalczyk, A. Craciun, E.A.P. Habets, “Generating virtual microphone signals in noisy environments,” Proc. European Signal Process. Conf. (EUSIPCO), Marrakech, Morocco, Sep. 2013.
[C13] D. Markovic, C. Hofmann, F. Antonacci, K. Kowalczyk, A. Sarti, and W. Kellermann, “Reflection coefficient estimation by pseudospectrum matching,” Proc. Int. Works. on Acoustic Sign. Enhancement (IWAENC), pp. 181-184, Aachen Germany, Sep. 2012.
[C12] P. Annibale, F. Antonacci, P. Bestagini, A. Brutti, A. Canclini, L. Cristoforetti, E. Habets, J. Filos, W. Kellermann, K. Kowalczyk, A. Lombard, E. Mabande, D. Markovic, P. Naylor, M. Omologo, R. Rabenstein, A. Sarti, P. Svaizer and M. Thomas, “The SCENIC project: space-time audio processing for environment-aware acoustic sensing and rendering,” Proc. 131st Audio Eng. Soc. Conv., New York, NY, Oct. 2011.
[C11] E. Mabande, H. Sun, K. Kowalczyk, and W. Kellermann, “Comparison of subspace-based and steered beamformer-based reflection localization methods,” Proc. European Signal Process. Conf. (EUSIPCO), Barcelona, Spain, Aug. 2011.
[C10] M. van Walstijn and K. Kowalczyk, “Formulation and analysis of frequency-dependent boundaries in finite-difference simulation with compact explicit schemes,” Proc. Forum Acusticum, Aalborg, Denmark, Jun/Jul. 2011.
[C9] E. Mabande, H. Sun, K. Kowalczyk, and W. Kellermann, “On 2D localization of reflectors using robust beamforming techniques,” Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (IEEE ICASSP), pp.153-156, Prag, Czech Republic, May 2011.
[C8] H. Sun, E. Mabande, K. Kowalczyk, and W. Kellermann, “Joint DOA and TDOA estimation for 3D localization of reflective surfaces using eigenbeam MVDR and spherical microphone arrays,” Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (IEEE ICASSP), pp.113-116, Prag, Czech Republic, May 2011.
[C7] K. Kowalczyk and M. van Walstijn, “Finite difference time domain modeling of phase grating diffusion,” Proc. IEEE Int. Symp. on Communications, Control and Signal Process. (IEEE ISCCSP), pp.1-4, Limassol, Cyprus, Mar. 2010.
[C6] K. Kowalczyk and M. van Walstijn, “A comparison of nonstaggered compact FDTD schemes for the 3D wave equation,” Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (IEEE ICASSP), pp.197-200, Dallas, TX, Mar. 2010.
[C5] M. van Walstijn and K. Kowalczyk, “On the numerical solution of the 2D wave equation with compact FDTD schemes,” Int. Conf. on Digital Audio Effects (DAFx), pp. 205-212, Espoo, Finland, Sep. 2008.
[C4] K. Kowalczyk and M. van Walstijn, “Modeling frequency-dependent boundaries as digital impedance filters in FDTD and K-DWM room acoustics simulations,” 124th Convention of the Audio Eng. Soc., Amsterdam, The Netherlands, May 2008. Winner of the AES Student Technical Papers Award
[C3] K. Kowalczyk and M. van Walstijn, “Virtual room acoustics using finite difference methods. How to model and analyze frequency-dependent boundaries?,” Proc. IEEE Int. Symp. on Communications, Control and Signal Process. (IEEE ISCCSP), pp.1504-1509, St. Julians, Malta, Mar. 2008
[C2] K. Kowalczyk and M. van Walstijn, “Formulation of a locally reacting wall in finite difference modeling of acoustic spaces,” Int. Symp. on Room Acoustics (ISRA), Seville, Spain, Sep. 2007.
[C1] K. Kowalczyk and M. van Walstijn, “On-line simulation of 2D resonators with reduced dispersion error using compact implicit finite difference schemes,” Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Process. (IEEE ICASSP), pp.285-288, Honolulu, Hawaii, Apr. 2007. Finalist of the IEEE ICASSP Best Student Paper Contest

Published abstracts, demos, show & tell contributions:
[A4] M. Rybicka, S. Kacprzak, M. Witkowski, and K. Kowalczyk, “Description of the DSP AGH systems for the SdSV Challenge”, Technical Report for Task2: Text-independent Speaker Verification at the Short-duration Speaker Verification (SdSV) Challenge, Annual Conf. Int. Speech Communication Association (INTERSPEECH), Shanghai, China, Oct. 2020.
[A3] M. Guzik, K. Kowalczyk, S. Woźniak, M. Fraś, K. Juros, D. Kaczor, P. Walas, “Acoustic source localization using drone-embedded microphone array,” in Journal of the Acoustical Society of America, vol. 146, no. 4, pp. 3058-3059, 2019.
[A2] W. Kellermann, E. Mabande, H. Sun, and K. Kowalczyk, “Precise and efficient localization of room reflections using compact microphone arrays,” J. Acoustical Society of America (JASA), vol. 131, pp. 3283, Apr. 2012.
[A1] P. Annibale, F. Antonacci, P. Bestagini, A. Brutti, A. Canclini, L. Cristoforetti, E. Habets, W. Kellermann, K. Kowalczyk, A. Lombard, E. Mabande, D. Markovic, P. Naylor, M. Omologo, R. Rabenstein, A. Sarti, P. Svaizer and M. Thomas, “The SCENIC project: environment-aware acoustic sensing and rendering,” Procedia in Computer Science, vol. 7, pp. 150-152, Oct. 2011.