Nobutaka ITO (Ph.D.)

Links

• Google Scholar Citations
• dblp

Short bio

Research Interests

• Source separation
• FastFCA: Fast method for separating more sources than microphones (joint diagonalizability constraint [Ito+2018IWAENC], generalized eigenvalue decomposition [Ito+2018EUSIPCO], multiplicative updates [Ito+2018GlobalSIP], application to multichannel nonnegative matrix factorization [Ito+2019ICASSP])
• Source location clustering based on directional statistics (cBMM [Ito+2018SpringerTextbook], cACGMM [Ito+2016EUSIPCO], cGMM [Ito+2014IWAENC], permmutation-free cGMM [Azcarreta+2018ICASSP], noisy cGMM [Ito+2018EUSIPCO])
• Noise reduction
• Noise reduction for robust automatic speech recognition (ASR) [Yoshioka+2015ASRU]
• Diffure noise suppression exploiting symmetry (crystal arrays [Ito+2011IEEETrans.ASLP], imaginary part method [Ito+2010ICASSP], matrix subspace [Ito+2015J.Sig.Pro.Sys.])
• Diffuse noise robust multiple source localization [Ito+2012INRIA]
• Composite noise reduction
• Overall optimization of linear prediction based dereverberation and symmetry-based diffuse noise reduction [Ito+2014ICASSP]
• Overall optimization of linear prediction based dereverberation and clustering-based source separation [Ito+2014IWAENC]
• Source counting
• Joint source separation and counting in reverberant environments [Ito+2014J.IEICE]
• Speaker diarization
• Probabilistic spatial dictionary (fundamental technique [Ito+2017ICASSP], spatiotemporal NMF [Ito+2018ICASSP])
• Image processing
• Image feature extraction based on complex moments [Ito+2008J.JSIAM]

Background

• 2003.4 - 2007.3   B.E. at the University of Tokyo, Japan
• 2007.4 - 2009.3   M.E. in Information Science and Technology at the University of Tokyo, Japan
• 2009.4 - 2012.3   Ph.D. in Information Science and Technology at the University of Tokyo, Japan
• 2009.9 - 2010.8   Student of Collège Doctoral Franco-Japonais (Visitor to Dr. Rémi Gribonval and Dr. Emmanuel Vincent, INRIA Rennes, France)
• 2010.4 - 2012.3   Research Fellow of the Japan Society for the Promotion of Science, Japan
• 2010.9 - 2010.10   Visitor to Dr. Rémi Gribonval and Dr. Emmanuel Vincent, INRIA Rennes, France
• 2012.1 - 2012.3   ditto
• 2012.4 - 2017.6   Researcher, NTT Communication Science Laboratories, NTT Corporation, Japan
• 2017.7 - Present   Research Scientist, NTT Communication Science Laboratories, NTT Corporation, Japan
• 2019.3 - Present   Visiting Industrial Fellow, University of Cambridge, United Kingdom (Visitor to Prof. Simon Godsill)

Academic Activities

1. Committee member, Community-Based Signal Separation Evaluation Campaign (SiSEC) (2013 -)
2. Invited talk at EUSIPCO2017 (2017)
3. Invited talk at EUSIPCO2015 (2015)
4. Member of Local Organisation Committee, LVA/ICA2010 (2010)
5. IEEE Kansai Section Young Professionals Affinity Group (2014 -   Committee member; 2017 -  Treasurer)
6. Member of Technical Committee on Engineering Acoustics, the Institute of Electronics, Information and Communication Engineers (IEICE), Japan (2017 -)
7. TPC member, the Institute of Electronics, Information and Communication Engineers (IEICE) General Conference, Japan (2018)
8. TPC member, the Institute of Electronics, Information and Communication Engineers (IEICE) Society Conference, Japan (2017)
9. Committee member, Young Researcher Exchange Meeting, the Acoustical Society of Japan Kansai Branch (2013 - 2016)
10. Deputy chair at the Spring/Autumn Meeting of the Acoustical Society of Japan
11. Reviewer of journals including IEEE Trans. ASLP, IEEE SPL, ASJ, and IEICE
12. Reviewer of conferences including ICASSP, EUSIPCO, and IWAENC
13. Committee member, Student and Young Researchers Forum, the Acoustical Society of Japan (2011 - 2013)

Awards

1. IWAENC 2018 Best Paper Award (2018)
2. IEEE Signal Processing Society Japan Chapter Student Paper Award (2011)
3. Japan Society for Industrial and Applied Mathematics Best Paper Award (2009)
4. Itakura Prize Innovative Young Researcher Award, the Acoustical Society of Japan (2015)
5. Awaya Prize Young Researcher Award, the Acoustical Society of Japan (2018)
6. ASRU 2015 Best Paper Award Honorable Mention (2015)
7. Best Student Presentation Award, the Acoustical Society of Japan (2011)
8. Best Presentation Award, Young Researcher Exchange Meeting, the Acoustical Society of Japan Kansai Branch (2011)
9. Senior Vice President's Award, Science and Core Technology Laboratory Group, NTT Corporation (2017)
10. Vice President's Award, Communication Science Laboratories, NTT Corporation (2019)
11. Vice President's Award, Communication Science Laboratories, NTT Corporation (2016)
12. Vice President's Award, Communication Science Laboratories, NTT Corporation (2014)

Intern Supervision

• Christopher Schymura (Ruhr-Universität Bochum, 2018.2 - 2018.3)
• Takashi Makino (Future University Hakodate, 2017.7 - 2017.8)
• Yuta Hashimoto (University of Toyama, 2017.7 - 2017.8)
• Juan Azcarreta (Polytechnic University of Catalonia, 2017.1 - 2017.8)
• Mahmoud Fakhry (University of Trento, 2015.11 - 2016.4)
• Kousuke Itakura (Kyoto University, 2015.8)
• Yu Teshima (Doshisha University, 2014.8)
• Ingrid Jafari (University of Western Australia, 2013)

Qualifications

1. TOEIC Institutional Program (IP) 990 (2012.11)
2. Eiken Grade 1 (2013.3)

Membership in Academic Societies

• Member of IEEE
• Member of the Acoustical Society of Japan

Publications

• Journal Papers

  1. T. Higuchi, N. Ito, S. Araki, T. Yoshioka, M. Delcroix, and T. Nakatani, "Online MVDR Beamformer Based on Complex Gaussian Mixture Model with Spatial Prior for Noise Robust ASR," IEEE/ACM Trans. Audio, Speech, and Language Processing (ASLP), vol. 25, no. 4, pp. 780 - 793, Apr. 2017. [IEEE Xplore]
  2. M. Delcroix, T. Yoshioka, A. Ogawa, Y. Kubo, M. Fujimoto, N. Ito, K. Kinoshita, M. Espi, S. Araki, T. Hori, and T. Nakatani, "Strategies for Distant Speech Recognition in Reverberant Environments," EURASIP Journal on Advances in Signal Processing, DOI: 10.1186/s13634-015-0245-7, 2015. [Springer]
  3. N. Ito, E. Vincent, T. Nakatani, N. Ono, S. Araki, and S. Sagayama, "Blind Suppression of Nonstationary Diffuse Acoustic Noise Based on Spatial Covariance Matrix Decomposition," Journal of Signal Processing Systems, vol. 79, no. 2, pp. 145 - 157, May 2015. [Springer] (invited journal extension of a conference paper)
  4. N. Ito, S. Araki, K. Kinoshita, and T. Nakatani, "Permutation-Free Clustering Method for Underdetermined Blind Source Separation Based on Source Location Information," IEICE (The Institute of Electronics, Information and Communication Engineers) Trans. Fundamentals of Electronics, Communications and Computer Sciences (Japanese Edition), vol. J97-A, no. 4, pp. 234 - 246, Apr. 2014. [IEICE] (in Japanese) (invited)
  5. N. Ito, H. Shimizu, N. Ono, and S. Sagayama, "Diffuse Noise Suppression Using Crystal-Shaped Microphone Arrays," IEEE Trans. Audio, Speech, and Language Processing (ASLP), vol. 19, no. 7, pp. 2101 - 2110, Sep. 2011. [IEEE Xplore] (IEEE Signal Processing Society Japan Chapter Student Paper Award; Itakura Prize Innovative Young Researcher Award)
  6. N. Ono, N. Ito, Y. Izumi, and S. Sagayama, "On the Relationship between Separation Performance by Ideal Time-Frequency Masking and Sparseness of Sources," IEICE (The Institute of Electronics, Information and Communication Engineers) Trans. Fundamentals of Electronics, Communications and Computer Sciences (Japanese Edition), vol. J92-A, no. 5, pp. 305 - 313, May 2009. [IEICE] (in Japanese)
  7. N. Ito, T. Nara, and T. Sakurai, "Image Feature Extraction Based on Complex Moments," Japan Journal of Industrial and Applied Mathematics, vol. 18, no. 1, pp. 135 - 153, Apr. 2008. [CiNii] (in Japanese) (Japan Society for Industrial and Applied Mathematics Best Paper Award)

• Book Chapters

  1. N. Ito, S. Araki, and N. Tomohiro, "Recent Advances in Multichannel Source Separation and Denoising Based on Source Sparseness," in Audio Source Separation, S. Makino, Ed., Springer, pp. 279 - 300, 2018. [Springer]
  2. M. Delcroix, T. Yoshioka, N. Ito, A. Ogawa, K. Kinoshita, M. Fujimoto, T. Higuchi, S. Araki, and T. Nakatani, "Multichannel Speech Enhancement Approaches to DNN-Based Far-Field Speech Recognition," in New Era for Robust Speech Recognition, S. Watanabe, M. Delcroix, F. Metze, and J.R. Hershey, Eds., Springer, pp. 21 - 49, 2017. [Springer]
  3. N. Ito, "What is Source Separation?", in Acousticpedia for Beginners, the Acoustical Society of Japan, Ed., Coronasha, pp. 40 - 43, 2017. (in Japanese) [Coronasha]

• Tutorial Papers

  1. T. Nakatani, N. Ito, T. Higuchi, S. Araki, K. Kinoshita, "Multiple Microphone Speech Enhancement for Distant Speech Recognition," the journal of the Institute of Noise Control Engineering of Japan (INCE/J), vol. 42, no. 1, pp. 16 - 19, Feb. 2018. (in Japanese) (invited)
  2. N. Ito, S. Araki, T. Nakatani, "Signal Enhancement in Any Environments," the Journal of the Acoustical Society of Japan, vol. 71, no. 3, pp. 136 - 142, Mar. 2015.(in Japanese) (invited)

• International Conference Papers (Peer Reviewed)

  1. N. Ito and T. Nakatani, "FastMNMF: Joint Diagonalization Based Accelerated Algorithms for Multichannel Nonnegative Matrix Factorization," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 371 - 375, May 2019. [IEEE Xplore]
  2. N. Ito and T. Nakatani, "Multiplicative Updates and Joint Diagonalization Based Acceleration for Under-Determined BSS Using a Full-Rank Spatial Covariance Model," Proc. IEEE Global Conf. Signal and Information Processing (GlobalSIP), pp. 231 - 235, Nov. 2018. [IEEE Xplore]
  3. N. Ito and T. Nakatani, "FastFCA-AS: Joint Diagonalization Based Acceleration of Full-Rank Spatial Covariance Analysis for Separating Any Number of Sources," Proc. IEEE Int'l Workshop Acoustic Signal Enhancement (IWAENC), pp. 151 - 155, Sep. 2018. [IEEE Xplore] (IWAENC 2018 Best Paper Award)
  4. Y. Matsui, T. Nakatani, M. Delcroix, K. Kinoshita, N. Ito, S. Araki, and S. Makino, "Online Integration of DNN-Based and Spatial Clustering-Based Mask Estimation for Robust MVDR Beamforming," Proc. IEEE Int'l Workshop Acoustic Signal Enhancement (IWAENC), pp. 71 - 75, Sep. 2018. [IEEE Xplore]
  5. N. Ito, S. Araki, and T. Nakatani, "FastFCA: Joint Diagonalization Based Acceleration of Audio Source Separation Using a Full-Rank Spatial Covariance Model," Proc. European Signal Processing Conf. (EUSIPCO), pp. 1681 - 1685, Sep. 2018. [EURASIP]
  6. N. Ito, C. Schymura, S. Araki, and T. Nakatani, "Noisy cGMM: Complex Gaussian Mixture Model with Non-Sparse Noise Model for Joint Source Separation and Denoising," Proc. European Signal Processing Conf. (EUSIPCO), pp. 1676 - 1680, Sep. 2018. [EURASIP]
  7. F.-R. Stöter, A. Liutkus, and N. Ito, "The 2018 Signal Separation Evaluation Campaign," Proc. Int'l Conf. Latent Variable Analysis and Signal Separation (LVA/ICA), pp. 293 - 305, Jul. 2018. [Springer]
  8. N. Ito, T. Makino, S. Araki, and T. Nakatani, "Maximum-Likelihood Online Speaker Diarization in Noisy Meetings Based on Categorical Mixture Model and Probabilistic Spatial Dictionary," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 546 - 550, Apr. 2018. [IEEE Xplore]
  9. J. Azcarreta, N. Ito, S. Araki, and T. Nakatani, "Permutation-Free cGMM: Complex Gaussian Mixture Model with Inverse Wishart Mixture Model Based Spatial Prior for Permutation-Free Source Separation and Source Counting," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 51 - 55, Apr. 2018. [IEEE Xplore]
  10. T. Higuchi, K. Kinoshita, N. Ito, S. Karita, and T. Nakatani, "Frame-by-Frame Closed-Form Update for Mask-Based Adaptive MVDR Beamforming," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 531 - 535, Apr. 2018. [IEEE Xplore]
  11. N. Ito, S. Araki, and T. Nakatani, "Data-Driven and Physical Model-Based Designs of Probabilistic Spatial Dictionary for Online Meeting Diarization and Adaptive Beamforming," Proc. European Signal Processing Conf. (EUSIPCO), pp. 1165 - 1169, Sep. 2017. [IEEE Xplore] (invited)
  12. S. Araki, N. Ito, M. Delcroix, A. Ogawa, K. Kinoshita, T. Higuchi, T. Yoshioka, D. Tran, S. Karita, and T. Nakatani, "Online Meeting Recognition in Noisy Environments with Time-Frequency Mask Based MVDR Beamforming," Proc. Joint Workshop on Hands-free Speech Communication and Microphone Arrays (HSCMA), pp. 16 - 20, Mar. 2017. [IEEE Xplore]
  13. N. Ito, S. Araki, M. Delcroix, and T. Nakatani, "Probabilistic Spatial Dictionary Based Online Adaptive Beamforming for Meeting Recognition in Noisy and Reverberant Environments," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 681 - 685, Mar. 2017. [IEEE Xplore]
  14. T. Nakatani, N. Ito, T. Higuchi, S. Araki, and K. Kinoshita, "Integrating DNN-Based and Spatial Clustering-Based Mask Estimation for Robust MVDR Beamforming," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 286 - 290, Mar. 2017. [IEEE Xplore]
  15. A. Liutkus, F.-R. Stöter, Z. Rafii, D. Kitamura, B. Rivet, N. Ito, N. Ono, and J. Fontecave, "The 2016 Signal Separation Evaluation Campaign," Proc. Int'l Conf. Latent Variable Analysis and Signal Separation (LVA/ICA), pp. 323 - 332, Feb. 2017. [Springer]
  16. M. Fakhry, N. Ito, S. Araki, and T. Nakatani, "Modeling Audio Directional Statistics Using a Probabilistic Spatial Dictionary for Speaker Diarization in Real Meetings," Proc. IEEE Int'l Workshop Acoustic Signal Enhancement (IWAENC), DOI: 10.1109/IWAENC.2016.7602903, Sep. 2016. [IEEE Xplore]
  17. N. Ito, S. Araki, and T. Nakatani, "Complex Angular Central Gaussian Mixture Model for Directional Statistics in Mask-Based Microphone Array Signal Processing," Proc. European Signal Processing Conf. (EUSIPCO), pp. 1153 - 1157, Sep. 2016. [IEEE Xplore]
  18. N. Ito, S. Araki, and T. Nakatani, "Modeling Audio Directional Statistics Using a Complex Bingham Mixture Model for Blind Source Extraction from Diffuse Noise," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 465 - 468, Mar. 2016. [IEEE Xplore]
  19. T. Higuchi, N. Ito, T. Yoshioka, and T. Nakatani, "Robust MVDR Beamforming Using Time-Frequency Masks for Online/Offline ASR in Noise," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 5210 - 5214, Mar. 2016. [IEEE Xplore]
  20. T. Yoshioka, N. Ito, M. Delcroix, A. Ogawa, K. Kinoshita, M. Fujimoto, C. Yu, W.J. Fabian, M. Espi, T. Higuchi, S. Araki, and T. Nakatani, "The NTT CHiME-3 System: Advances in Speech Enhancement and Recognition for Mobile Multi-Microphone Devices," Proc. IEEE Workshop Automatic Speech Recognition and Understanding (ASRU), pp. 436 - 443, Dec. 2015. [IEEE Xplore] (ASRU 2015 Best Paper Award Honorable Mention)
  21. N. Ito, S. Araki, and T. Nakatani, "Permutation-Free Clustering of Relative Transfer Function Features for Blind Source Separation," Proc. European Signal Processing Conf. (EUSIPCO), pp. 409 - 413, Aug. 2015. [IEEE Xplore] (invited)
  22. N. Ono, Z. Rafii, D. Kitamura, N. Ito, and A. Liutkus, "The 2015 Signal Separation Evaluation Campaign," Proc. Int'l Conf. Latent Variable Analysis and Signal Separation (LVA/ICA), pp. 387 - 395, Aug. 2015. [Springer]
  23. M. Delcroix, T. Yoshioka, A. Ogawa, Y. Kubo, M. Fujimoto, N. Ito, K. Kinoshita, M. Espi, S. Araki, T. Hori, and T. Nakatani, "Defeating Reverberation: Advanced Dereverberation and Recognition Techniques for Hands-Free Speech Recognition," Proc. IEEE Global Conf. Signal and Information Processing (GlobalSIP), pp. 522 - 526, Dec. 2014. [IEEE Xplore] (invited)
  24. N. Ito, S. Araki, T. Yoshioka, and T. Nakatani, "Relaxed Disjointness Based Clustering for Joint Blind Source Separation and Dereverberation," Proc. IEEE Int'l Workshop Acoustic Signal Enhancement (IWAENC), pp. 268 - 272, Sep. 2014. [IEEE Xplore]
  25. M. Delcroix, T. Yoshioka, A. Ogawa, Y. Kubo, M. Fujimoto, N. Ito, K. Kinoshita, M. Espi, T. Hori, T. Nakatani, and A. Nakamura, "Linear Prediction-Based Dereverberation with Advanced Speech Enhancement and Recognition Technologies for the REVERB Challenge," Proc. REVERB Workshop, May 2014. [REVERB Workshop]
  26. N. Ito, S. Araki, and T. Nakatani, "Probabilistic Integration of Diffuse Noise Suppression and Dereverberation," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 5167 - 5171, May 2014. [IEEE Xplore]
  27. N. Ono, Z. Koldovský, S. Miyabe, and N. Ito, "The 2013 Signal Separation Evaluation Campaign," Proc. IEEE Int'l Workshop Machine Learning for Signal Processing (MLSP), DOI: 10.1109/MLSP.2013.6661988, Sep. 2013. [IEEE Xplore]
  28. N. Ito, E. Vincent, N. Ono, and S. Sagayama, "General Algorithms for Estimating Spectrogram and Transfer Functions of Target Signal for Blind Suppression of Diffuse Noise," Proc. IEEE Int'l Workshop Machine Learning for Signal Processing (MLSP), DOI: 10.1109/MLSP.2013.6661984, Sep. 2013. [IEEE Xplore] (invited to journal extension)
  29. I. Jafari, N. Ito, M. Souden, S. Araki, and T. Nakatani, "Source Number Estimation Based on Clustering of Speech Activity Sequences for Microphone Array Processing," Proc. IEEE Int'l Workshop Machine Learning for Signal Processing (MLSP), DOI: 10.1109/MLSP.2013.6661990, Sep. 2013. [IEEE Xplore]
  30. N. Ito, S. Araki, and T. Nakatani, "Permutation-Free Convolutive Blind Source Separation via Full-Band Clustering Based on Frequency-Independent Source Presence Priors," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 3238 - 3242, May 2013. [IEEE Xplore]
  31. N. Ito, E. Vincent, N. Ono, R. Gribonval, and S. Sagayama, "Crystal-MUSIC: Accurate Localization of Multiple Sources in Diffuse Noise Environments Using Crystal-Shaped Microphone Arrays," Proc. Int'l Conf. Latent Variable Analysis and Signal Separation (LVA/ICA), pp. 81 - 88, Sep. 2010. [Springer]
  32. N. Ito, N. Ono, E. Vincent, and S. Sagayama, "Designing the Wiener Post-Filter for Diffuse Noise Suppression Using Imaginary Parts of Inter-Channel Cross-Spectra," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 2818 - 2821, Mar. 2010. [IEEE Xplore]
  33. N. Ono, H. Kohno, N. Ito, and S. Sagayama, "Blind Alignment of Asynchronously Recorded Signals for Distributed Microphone Array," Proc. IEEE Workshop Applications of Signal Processing to Audio and Acoustics (WASPAA), pp. 161 - 164, Oct. 2009. [IEEE Xplore]
  34. Y. Kamamoto, N. Harada, T. Moriya, N. Ito, N. Ono, T. Nishimoto, and S. Sagayama, "An Efficient Lossless Compression of Multichannel Time-Series Signals by MPEG-4 ALS," Proc. IEEE Int'l Symposium Consumer Electronics (ISCE), pp. 159 - 163, May 2009. [IEEE Xplore]
  35. N. Ono, N. Ito, and S. Sagayama, "Five Classes of Crystal Arrays for Blind Decorrelation of Diffuse Noise," Proc. IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM), pp. 151 - 154, Jul. 2008. [IEEE Xplore]
  36. N. Ito, N. Ono, and S. Sagayama, "A Blind Noise Decorrelation Approach with Crystal Arrays on Designing Post-Filters for Diffuse Noise Suppression," Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP), pp. 317 - 320, Apr. 2008. [IEEE Xplore]
  37. T. Nara, N. Ito, T. Takamatsu, and T. Sakurai, "Direct Computation of Harmonic Moments for Tomographic Reconstruction," Journal of Physics: Conference Series, vol. 73, DOI: 10.1088/1742-6596/73/1/012017, 2007. [IOPSCIENCE]

• Preprints

  1. N. Ito and S. Godsill, "A Multi-Target Track-Before-Detect Particle Filter Using Superpositional Data in Non-Gaussian Noise," uploaded on 11 Mar. 2020. [PDF]
  2. N. Ito and T. Nakatani, "FastFCA-AS: Joint Diagonalization Based Acceleration of Full-Rank Spatial Covariance Analysis for Separating Any Number of Sources," arXiv, arXiv:1805.09498, May 2018.
  3. N. Ito, S. Araki, and T. Nakatani, "FastFCA: A Joint Diagonalization Based Fast Algorithm for Audio Source Separation Using a Full-Rank Spatial Covariance Model," arXiv, arXiv:1805.06572, May 2018.
  4. F.-R. Stöter, A. Liutkus, and N. Ito, "The 2018 Signal Separation Evaluation Campaign," arXiv, arXiv:1804.06267, Apr. 2018.
  5. N. Ito, E. Vincent, N. Ono, and S. Sagayama, "Robust Estimation of Directions-of-Arrival in Diffuse Noise Based on Matrix-Space Sparsity," Research Report, INRIA, RR-8120, hal-00746271, Oct. 2012.
  6. T. Nara, N. Ito, S. Ando, T. Takamatsu, and T. Sakurai, "Direct Computation of Harmonic Moments for Tomographic Reconstruction," Mathematical Engineering Technical Reports, the University of Tokyo, METR 2006-58, Nov. 2006.

• Domestic Conference Papers (Not Peer Reviewed)

  1. N. Ito, S. Araki, and T. Nakatani, "FastFCA: Fast Algorithm for Audio Source Separation Using Time-Varying Complex Gaussian Distribution Based on Joint Diagonalization of Spatial Covariance Matrices," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 427 - 430, 2018. (in Japanese)
  2. N. Ito, S. Araki, M. Delcroix, and T. Nakatani, "Speech Enhancement for Meeting Speech Recognition Based on Online Speaker Diarization and Adaptive Beamforming Using Probabilistic Spatial Dictionary," Proc. Autumn Meeting of the Acoustical Society of Japan (ASJ), 2017. (in Japanese)
  3. N. Ito, S. Araki, and T. Nakatani, "Complex Angular Central Gaussian Mixture Model for Directional Statistics Based Blind Source Separation," Proc. Autumn Meeting of the Acoustical Society of Japan (ASJ), 2017. (in Japanese) (Awaya Prize Young Researcher Award)
  4. S. Araki, K. Kinoshita, N. Ito, A. Ogawa, M. Delcroix, T. Higuchi, T. Yoshioka, D. Tran, and T. Nakatani, "Conversation Speech Recognition in Noisy Environments," Proc. Autumn Meeting of the Acoustical Society of Japan (ASJ), pp. 1265 - 1268, 2016. (in Japanese)(invited)
  5. N. Ito, S. Araki, M. Fakhry, and T. Nakatani, "Multiple Speaker Diarization Based on Modeling Directional Statistics Using Statistical Spatial Dictionary," Proc. Autumn Meeting of the Acoustical Society of Japan (ASJ), pp. 321 - 324, 2016. (in Japanese)
  6. N. Minematsu, Y. Akita, T. Asami, N. Ito, T. Ochiai, T. Koriyama, D. Saito, S. Shiota, T. Shinozaki, M. Suzuki, S. Takagi, N. Tawara, K. Hashimoto, T. Higuchi, and T. Fukuda, "Attendance Report of International Conference ICASSP2016," the Special Interest Group Technical Reports of Information Processing Society of Japan (IPSJ), vol. 2016-SLP-112, no. 5, pp. 1 - 6, Jul. 2016. (in Japanese)
  7. N. Ito, S. Araki, and T. Nakatani, "Complex Bingham Mixture Models for Directional Statistics Modeling and Blind Diffuse Noise Reduction," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 629 - 630, 2016. (in Japanese)
  8. T. Higuchi, N. Ito, T. Yoshioka, and T. Nakatani, "Online MVDR Beamforming Based on Time-Frequency Masking," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 559 - 560, 2016. (in Japanese)
  9. T. Nakatani, N. Ito, T. Higuchi, S. Araki, T. Yoshioka, M. Fujimoto, and K. Kinoshita, "NTT CHiME-3 Speech Recognition System: Noise-Robust Frontend," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 57 - 60, 2016. (in Japanese)
  10. T. Yoshioka, M. Delcroix, A. Ogawa, C. Yu, N. Ito, K. Kinoshita, M. Fujimoto, W. Fabian, M. Espi, T. Higuchi, S. Araki, and T. Nakatani, "NTT CHiME-3 Speech Recognition System: System Overview and Back-End Techniques," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 55 - 56, 2016. (in Japanese)
  11. N. Ito, S. Araki, and T. Nakatani, "Multichannel Noise Suppression Based on Permutation-Free Clustering," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 587 - 588, 2015. (in Japanese)
  12. N. Ito, S. Araki, and T. Nakatani, "Probabilistic Model Integration of Clustering-Based Source Separation and Linear Prediction-Based Dereverberation," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 547 - 548, 2015. (in Japanese)
  13. N. Ito, S. Araki, and T. Nakatani, "Joint Blind Source Separation and Counting for Reverberant Underdetermined Mixtures Based on Source Location and Activation," Proc. Autumn Meeting of the Acoustical Society of Japan (ASJ), pp. 521 - 522, 2014. (in Japanese)
  14. M. Delcroix, K. Kinoshita, T. Yoshioka, A. Ogawa, Y. Kubo, M. Fujimoto, N. Ito, M. Espi, T. Hori, T. Nakatani, and A. Nakamura, "Speech Enhancement and Recognition for Reverberant Speech: Overview of the NTT REVERB Challenge System," the Special Interest Group Technical Reports of Information Processing Society of Japan (IPSJ), vol. 2014-SLP-102, no. 5, pp. 1 - 4, Jul. 2014. (in Japanese)
  15. N. Ito, S. Araki, and T. Nakatani, "Joint Blind Suppression of Diffuse Noise and Reverberation Based on Probabilistic Model Integration," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 667 - 668, 2014. (in Japanese)
  16. N. Ito, I. Jafari, S. Araki, and T. Nakatani, "Source Number Estimation under Reverberant and Underdetermined Conditions Based on Clustering of Source Activity Sequences," Technical Report of the Institute of Electronics, Information and Communication Engineers (IEICE), vol. 113, no. 242, pp. 17 - 21, Oct. 2013. (in Japanese)
  17. N. Ito, S. Araki, and T. Nakatani, "Permutation-Free Clustering-Based Source Separation Based on Time-Varying Mixture Weights," Technical Report of the Institute of Electronics, Information and Communication Engineers (IEICE), vol. 113, no. 28, pp. 7 - 12, May 2013. (in Japanese)
  18. N. Ito, E. Vincent, N. Ono, R. Gribonval, and S. Sagayama, "Diffuse Noise Robust Multiple Source Localization Based on Matrix Completion via Trace Norm Minimization," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 665 - 666, 2011. (in Japanese) (Best Student Presentation Award)
  19. T. Ono, N. Ito, S. Miyabe, N. Ono, and S. Sagayama, "Blind Source Separation with Distributed Microphone Arrays and Investigation of Performance Gain Using Post-Filter," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 655 - 656, 2011. (in Japanese)
  20. T. Ono, N. Ito, S. Miyabe, N. Ono, and S. Sagayama, "Blind Source Separation with Distributed Microphone Pairs and Investigation of Performance Gain Using Post-Filter," Technical Report of the Institute of Electronics, Information and Communication Engineers (IEICE), vol. 110, no. 331, pp. 25 - 30, Dec. 2010. (in Japanese)
  21. N. Ito, Y. Kitano, N. Ono, and S. Sagayama, "Instrument Separation in Reverberant Environments Using Crystal Microphone Arrays," the Special Interest Group Technical Reports of Information Processing Society of Japan (IPSJ), vol. 2009-MUS-82, no. 3, pp. 1 - 6, Dec. 2009. (in Japanese)
  22. N. Ito, N. Ono, and S. Sagayama, "Diffuse Noise Suppression Based on the Imaginary Parts of the Inter-Channel Cross-Spectra with a Small-Sized Microphone Array," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 705 - 706, 2009. (in Japanese)
  23. H. Kohno, N. Ito, N. Ono, and S. Sagayama, "Blind Alignment of Received Signals to Localize Sources and Microphones," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 703 - 704, 2009. (in Japanese)
  24. N. Ito, N. Ono, and S. Sagayama, "Investigation of Real-Environmental Noise Suppression with a Crystal Array," Proc. Autumn Meeting of the Acoustical Society of Japan (ASJ), pp. 677 - 678, 2008. (in Japanese)
  25. N. Ito, N. Ono, and S. Sagayama, "Diffuse Noise Suppression by Crystal-Array-Based Post-Filter Design," Technical Report of the Institute of Electronics, Information and Communication Engineers (IEICE), vol. 108, no. 68, pp. 43 - 46, May 2008. (in Japanese)
  26. N. Ito, N. Ono, and S. Sagayama, "Diffuse Noise Suppression Based on Post-Filtering Using Crystal Arrays," Proc. Spring Meeting of the Acoustical Society of Japan (ASJ), pp. 695 - 696, 2008. (in Japanese)
  27. S. Araki, N. Ito, H. Sawada, N. Ono, S. Makino, and S. Sagayama, "Initial Value Estimation for Frequency Domain ICA from Limited Data," Proc. the Institute of Electronics, Information and Communication Engineers (IEICE) General Conference, p. 208, Mar. 2008. (in Japanese)
  28. N. Ono, Y. Izumi, N. Ito, and S. Sagayama, "Source Separation by Time-Variant Filters Based on Stochastic Models," Technical Report of the Institute of Electronics, Information and Communication Engineers (IEICE), vol. 107, no.240, pp. 25 - 30, Sep. 2007. (in Japanese) (invited)
  29. N. Ono, H. Kohno, H. Shimizu, N. Ito, and S. Sagayama, "A Group-theoretical Consideration on Array Arrangements to Orthogonalize Isotropic Noise Field," Proc. Autumn Meeting of the Acoustical Society of Japan (ASJ), pp. 621 - 622, 2007. (in Japanese)
  30. N. Ito, N. Ono, and S. Sagayama, "A Nonlinear Beamformer in the Isotropic Noise Field Using Crystal Arrays," Proc. Autumn Meeting of the Acoustical Society of Japan (ASJ), pp. 619 - 620, 2007. (in Japanese)

• Conference Presentations (No Proceedings)

  1. N. Ito, S. Araki, and T. Nakatani, "A New Application of Joint Diagonalization Based on the Generalized Eigenvalue Problem: Computation Reduction of Source Separation," Meeting of the Union of Research Activity Groups, Japan Society for Industrial and Applied Mathematics, Mar. 2018. (in Japanese)
  2. N. Ito, T. Nara, and T. Sakurai, "On Complex Moments of Images and their Projections," Meeting of the Union of Research Activity Groups, Japan Society for Industrial and Applied Mathematics, Mar. 2007. (in Japanese)
  3. T. Nara, N. Ito, S. Ando, T. Takamatsu, and T. Sakurai, "Direct Computation of Harmonic Moments from Projections," The 6th Symposium of Mathematical Aspects of Image Processing and Computer Vision, Nov. 2006. (invited)

• Theses

  • "Robust Microphone Array Signal Processing against Diffuse Noise," Ph.D. Dissertation, the University of Tokyo, Japan, Mar. 2012.
  • "Microphone Array Signal Processing for Diffuse Noise Suppression," Master's Thesis, the University of Tokyo, Japan, Mar. 2009.
  • "Study on Complex Moments of Images and their Projections," Bachelor's Thesis, the University of Tokyo, Japan, Mar. 2007. (in Japanese)