## Journal Papers

- Y. Takida, S. Koyama, N. Ueno, and H. Saruwatari, “Reciprocity gap functional in spherical harmonic domain for gridless sound field decomposition,” Elsevier Signal Processing, vol. 169, 2020.
- Y. Mitsufuji, S. Uhlich, N. Takamune, D. Kitamura, S. Koyama, and H. Saruwatari, “Multichannel Non-Negative Matrix Factorization Using Banded Spatial Covariance Matrices in Wavenumber Domain,” IEEE/ACM Transactions on Audio, Speech, and Language Processing, vol. 28, pp. 49-60, 2020.
- N. Ueno, S. Koyama, and H. Saruwatari, “Three-Dimensional Sound Field Reproduction Based on Weighted Mode-Matching Method,” IEEE/ACM Transactions on Audio, Speech, and Language Processing, vol. 27, no. 12, pp. 1852-1867, 2019.
- S. Koyama and L. Daudet, “Sparse Representation of a Spatial Sound Field in a Reverberant Environment,” IEEE Journal of Selected Topics in Signal Processing, vol. 13, no. 1, pp. 172-184, 2019.
- S. Koyama, N. Murata, and H. Saruwatari, “Sparse Sound Field Decomposition for Super-resolution in Recording and Reproduction,” Journal of the Acoustical Society of America, vol. 143, no. 6, pp. 3780-3895, 2018.
- N. Murata, S. Koyama, N. Takamune, and H. Saruwatari, “Sparse Representation Using Multidimensional Mixed-Norm Penalty With Application to Sound Field Decomposition,” IEEE Transactions on Signal Processing, vol. 66, no. 12, pp. 3327-3338, 2018.
- S. Koyama, K. Furuya, K. Wakayama, S. Shimauchi, and H. Saruwatari, “Analytical approach to transforming filter design for sound field recording and reproduction using circular arrays with a spherical baffle,” Journal of the Acoustical Society of America, vol. 139, no. 3, pp. 1024-1036, 2016.
- S. Koyama, K. Furuya, Y. Haneda, and H. Saruwatari, “Source-Location-Informed Sound Field Recording and Reproduction,” IEEE Journal of Selected Topics in Signal Processing, vol. 9, no. 5, pp. 881-894, 2015.
- Y. Haneda, K. Furuya, S. Koyama, K. Niwa, and K. Kobayashi, “Sound field simulation for circular array based on spatial circular convolution,” Acoustical Science and Technology, vol. 35, no. 2, pp. 99-107, 2014.
- Y. Haneda, K. Furuya, S. Koyama, and K. Niwa, “Close-talking microphone arrays based on spherical harmonic expansion,” IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, vol. J97-A, no. 4, pp. 264-273, 2014. (in Japanese)
- S. Koyama, K. Furuya, H. Uematsu, Y. Hiwasaki, and Y. Haneda, “Real-time Sound Field Transmission System by Using Wave Field Reconstruction Filter and Its Evaluation,” IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, vol. E97-A, no. 9, pp. 1840-1848, 2014. (Copyright © 2014 IEICE)
- S. Koyama, K. Furuya, Y. Hiwasaki, Y. Haneda, and Y. Suzuki, “Wave Field Reconstruction Filtering in Cylindrical Harmonic Domain for With-Height Recording and Reproduction,” IEEE/ACM Transactions on Audio, Speech, and Language Processing, vol. 22, no. 10, pp. 1546-1557, 2014.
- S. Koyama, K. Furuya, Y. Hiwasaki, and Y. Haneda, “Analytical Approach to Wave Field Reconstruction Filtering in Spatio-Temporal Frequency Domain,” IEEE Transactions on Audio, Speech, and Language Processing, vol. 21, no. 4, pp. 685-696, 2013.
- S. Koyama, K. Furuya, Y. Hiwasaki, and Y. Haneda, “Reproducing Virtual Sound Sources in Front of a Loudspeaker Array Using Inverse Wave Propagator,” IEEE Transactions on Audio, Speech, and Language Processing, vol. 20, no. 6, pp. 1746-1758, 2012. [The Telecom System Technology Award, the Telecommunication Advancement Foundation]
- S. Koyama, T. Kurihara, and S. Ando, “A Theory and Experiment of Instantaneous Wave Source Localization from a Wave Distribution on a Small Region,” IEEJ Transactions of Sensors and Micromachines, vol. 129-E, no. 10, pp. 350-356, 2009. (in Japanese) [The Best Young Researcher Paper Award, IEEJ Sensors and Micromachines Society]

## Letters

- N. Ueno, S. Koyama, and H. Saruwatari, “Sound Field Recording Using Distributed Microphones Based on Harmonic Analysis of Infinite Order,” IEEE Signal Processing Letters, vol. 25, no. 1, pp. 135-139, 2018.
- J. Trevino, S. Koyama, S. Sakamoto, and Y. Suzuki, “Mixed-order Ambisonics encoding of cylindrical microphone array signals,” Acoustical Science and Technology, Acoustical Letter, vol. 35, no. 3, pp. 174-177, 2014.

## Overview / Tutorial Papers

- S. Koyama, “Sparsity-based sound field reconstruction,” Acoustical Science and Technology, vol. 41, no. 1, pp. 269-275, 2020.
- S. Koyama, G. Chardon, and L. Daudet, “Optimizing Source and Sensor Placement for Sound Field Control: An Overview,” IEEE/ACM Transactions on Audio, Speech, and Language Processing, 2020. (in press)
- S. Koyama, “The Future of Sound Recording, Reproduction, and Editing,” Journal of IEICE, vol. 100, no. 6, pp. 474-478, 2017. (in Japanese) (Copyright © 2017 IEICE)
- S. Koyama, “Sparse sound field representation for super-resolution in recording and reproduction,” Journal of the Acoustical Society of Japan, vol. 71, no. 11, pp. 632-638, 2015. (in Japanese)
- K. Furuya and S. Koyama, “Wave Field Synthesis; Principles and applications,” Journal of the Institute of Image Information and Television Engineers, vol. 68, no. 8, pp. 621-624, 2014. (in Japanese)
- S. Koyama, “Mathematical formulation of sound field reproduction –Mathematics in Wave Field Synthesis and Higher Order Ambisonics–,” Journal of the Acoustical Society of Japan, vol. 68, no. 11, pp. 584-589, 2012. (in Japanese)

## International Conferences

- M. Nakanishi, N. Ueno, S. Koyama, and H. Saruwatari, “Two-Dimensional Sound Field Recording With Multiple Circular Microphone Arrays Considering Multiple Scattering,” in Proceedings of IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA), New Paltz, 2019, pp. 363-367.
- H. Ito, S. Koyama, N. Ueno, and H. Saruwatari, “Three-Dimensional Spatial Active Noise Control Based on Kernel-Induced Sound Field Interpolation,” in Proceedings of International Congress on Acoustics (ICA), Aachen, 2019, pp. 1101-1108.
- Y. Takida, S. Koyama, N. Ueno, and H. Saruwatari, “Comparison of Interpolation Methods for Gridless Sound Field Decomposition Based on Reciprocity Gap Functional,” in Proceedings of International Congress on Sound and Vibration (ICSV), Montreal, 2019. [Invited]
- H. Ito, S. Koyama, N. Ueno, and H. Saruwatari, “Feedforward Spatial Active Noise Control Based on Kernel Interpolation of Sound Field,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Brighton, 2019, pp. 511-515. [Best Student Paper Award, IEEE SPS Japan Student Conference Paper Award]
- Y. Takida, S. Koyama, N. Ueno, and H. Saruwatari, “Robust Gridless Sound Field Decomposition Based on Structured Reciprocity Gap Functional in Spherical Harmonic Domain,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Brighton, 2019, pp. 581-585.
- S. Koyama, “Sparsity-based sound field reconstruction,” in Tohoku Universal Acoustical Communication Month, Seminar on the spatial aspects of hearing and their applications, keynote lecture, Sendai, 2018. [Invited]
- N. Ueno, S. Koyama, and H. Saruwatari, “Kernel Ridge Regression With Constraint of Helmholtz Equation for Sound Field Interpolation,” in Proceedings of International Workshop on Acoustic Signal Enhancement (IWAENC), Tokyo, 2018, pp. 436-440.
- Y. Takida, S. Koyama, and H. Saruwatari, “Exterior and Interior Sound Field Separation Using Convex Optimization: Comparison of Signal Models,” in Proceedings of European Signal Processing Conference (EUSIPCO), Rome, 2018, pp. 2567-2571.
- Y. Takida, S. Koyama, N. Ueno, and H. Saruwatari, “Gridless Sound Field Decomposition Based on Reciprocity Gap Functional in Spherical Harmonic Domain,” in Proceedings of IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM), Sheffield, 2018, pp. 627-631. [Best Student Paper Award, ONRG sponsored student travel grants]
- S. Koyama, G. Chardon, and L. Daudet, “Joint Source and Sensor Placement for Sound Field Control Based on Empirical Interpolation Method,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Calgary, 2018, pp. 501-505.
- N. Ueno, S. Koyama, and H. Saruwatari, “Sound Field Reproduction with Exterior Radiation Cancellation Using Analytical Weighting of Harmonic Coefficients,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Calgary, 2018, pp. 466-470. [IEEE SPS Japan Student Conference Paper Award]
- S. Koyama and L. Daudet, “Comparison of Reverberation Models for Sparse Sound Field Decomposition,” in Proceedings of IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA), New Paltz, 2017, pp. 214-218.
- S. Koyama, N. Murata, and H. Saruwatari, “Effect of Multipole Dictionary in Sparse Sound Field Decomposition For Super-resolution in Recording and Reproduction,” in Proceedings of International Congress on Sound and Vibration (ICSV), London, 2017. [Invited]
- N. Ueno, S. Koyama, and H. Saruwatari, “Listening-area-informed Sound Field Reproduction With Gaussian Prior Based On Circular Harmonic Expansion,” in Proceedings of Hands-free Speech Communication and Microphone Arrays (HSCMA), San Francisco, 2017, pp. 196-200.
- N. Ueno, S. Koyama, and H. Saruwatari, “Listening-area-informed Sound Field Reproduction Based On Circular Harmonic Expansion,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), New Orleans, 2017, pp. 111-115.
- N. Murata, S. Koyama, N. Takamune, and H. Saruwatari, “Spatio-temporal Sparse Sound Field Decomposition Considering Acoustic Source Signal Characteristics,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), New Orleans, 2017, pp. 441-445.
- H. Nakajima, D. Kitamura, N. Takamune, S. Koyama, H. Saruwatari, Y. Takahashi, and K. Kondo, “Audio Signal Separation using Supervised NMF with Time-variant All-Pole-Model-Based Basis Deformation,” in Proceedings of Asia-Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA ASC), Jeju, 2016. [Invited]
- S. Koyama, N. Murata, and H. Saruwatari, “Super-resolution in sound field recording and reproduction based on sparse representation,” in 5th Joint Meeting of the Acoustical Society of America and Acoustical Society of Japan, Honolulu, 2016. [Invited]
- N. Murata, H. Kameoka, K. Kinoshita, S. Araki, T. Nakatani, S. Koyama, and H. Saruwatari, “Reverberation-robust underdetermined source separation with non-negative tensor double deconvolution,” in Proceedings of European Signal Processing Conference (EUSIPCO), Budapest, 2016, pp. 1648-1652.
- H. Nakajima, D. Kitamura, N. Takamune, S. Koyama, H. Saruwatari, N. Ono, Y. Takahashi, and K. Kondo, “Music Signal Separation Using Supervised NMF with All-Polle-Model-Based Discriminative Basis Deformation,” in Proceedings of European Signal Processing Conference (EUSIPCO), Budapest, 2016, pp. 1143-1147.
- S. Koyama, “Source-Location-Informed Sound Field Recording and Reproduction: A Generalization to Arrays of Arbitrary Geometry,” in Proceedings of 2016 AES International Conference on Sound Field Control, Guildford, 2016. [Invited]
- Y. Mitsufuji, S. Koyama, and H. Saruwatari, “Multichannel Blind Source Separation Based on Non-negative Tensor Factorization in Wavenumber Domain,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Shanghai, 2016, pp. 56-60.
- N. Murata, S. Koyama, H. Kameoka, N. Takamune, and H. Saruwatari, “Sparse Sound Field Decomposition with Multichannel Extension of Complex NMF,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Shanghai, 2016, pp. 395-399.
- S. Koyama and H. Saruwatari, “Sound Field Decomposition in Reverberant Environment Using Sparse and Low-rank Signal Models,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Shanghai, 2016, pp. 345-349.
- S. Koyama, A. Matsubayashi, N. Murata, and H. Saruwatari, “Sparse Sound Field Decomposition Using Group Sparse Bayesian Learning,” in Proceedings of Asia-Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA ASC), Hong Kong, 2015, pp. 850-855. [Invited]
- N. Murata, S. Koyama, N. Takamune, and H. Saruwatari, “Sparse Sound Field Decomposition with Parametric Dictionary Learning for Super-Resolution Recording and Reproduction,” in Proceedings of IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP), Cancun, 2015, pp. 69-72.
- S. Koyama, K. Ito, and H. Saruwatari, “Source-location-informed sound field recording and reproduction with spherical arrays,” in Proceedings of IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA), New Paltz, 2015.
- Y. Murota, D. Kitamura, S. Koyama, H. Saruwatari, and S. Nakamura, “Statistical modeling of binaural signal and its application to binaural source separation,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Brisbane, 2015, pp. 494-498.
- S. Koyama, N. Murata, and H. Saruwatari, “Structured sparse signal models and decomposition algorithm for super-resolution in sound field recording and reproduction,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Brisbane, 2015, pp. 619-623.
- S. Koyama, P. Srivastava, K. Furuya, S. Shimauchi, and H. Ohmuro, “STSP: Space-Time Stretched Pulse for Measuring Spatio-Temporal Impulse Response,” in Proceedings of International Workshop on Acoustic Signal Enhancement (IWAENC), Antibes, 2014, pp. 309-313.
- Y. Haneda, K. Furuya, S. Koyama, and K. Niwa, “Close-talking spherical microphone array using sound pressure interpolation based on spherical harmonic expansion,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Florence, 2014, pp. 604-608.
- S. Koyama, S. Shimauchi, and H. Ohmuro, “Sparse Sound Field Representation in Recording and Reproduction for Reducing Spatial Aliasing Artifacts,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Florence, 2014, pp. 4443-4447.
- S. Koyama, K. Furuya, Y. Hiwasaki, and Y. Haneda, “MAP Estimation of Driving Signals of Loudspeakers for Sound Field Reproduction From Pressure Measurements,” in Proceedings of IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA), New Paltz, 2013.
- S. Koyama, K. Furuya, H. Uematsu, Y. Hiwasaki, and Y. Haneda, “Real-time sound field transmission system by using wave field reconstruction filter and its subjective listening test,” in Proceedings of 52nd AES International Conference, Guildford, 2013.
- H. Takada, M. Date, S. Koyama, S. Ozawa, S. Mieda, and A. Kojima, “High-reality space composition using stably-positioned imaging and acoustic wave field synthesis,” in Proceedings of 36th European Conference on Visual Perception (ECVP), Bremen, 2013, p. 224.
- S. Koyama, T. Lee, K. Furuya, Y. Hiwasaki, and Y. Haneda, “Improvement using circular harmonics beamforming on reverberation problem of wave field reconstruction filtering,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Vancouver, 2013, pp. 276-280.
- S. Koyama, K. Furuya, Y. Hiwasaki, Y. Haneda, and Y. Suzuki, “Sound field reproduction using multiple linear arrays based on wave field reconstruction filtering in helical wave spectrum domain,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Vancouver, 2013, pp. 271-275.
- S. Emura, S. Koyama, K. Furuya, and Y. Haneda, “Posterior Residual Echo Canceling and its Complexity Reduction in the Wave Domain,” in Proceedings of International Workshop on Acoustic Signal Enhancement (IWAENC), Aachen, 2012.
- S. Koyama, K. Furuya, Y. Hiwasaki, and Y. Haneda, “Sound Field Reproduction Method in Spatio-Temporal Frequency Domain Considering Directivity of Loudspeakers,” in Proceedings of 132nd AES Convention, Budapest, 2012.
- S. Koyama, K. Furuya, Y. Hiwasaki, and Y. Haneda, “Design of Transform Filter for Reproducing Arbitrary Shifted Sound Field Using Phase-Shift of Spatio-Temporal Frequency,” in Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Kyoto, 2012, pp. 381-384.
- S. Koyama, K. Furuya, Y. Hiwasaki, and Y. Haneda, “Sound Field Recording and Reproduction Using Transform Filter Designed in Spatio-Temporal Frequency Domain,” in Proceedings of 131st AES Convention, New York, 2011.
- S. Koyama, K. Furuya, Y. Hiwasaki, and Y. Haneda, “Design of Transform Filter for Sound Field Reproduction Using Microphone Array and Loudspeaker Array,” in Proceedings of IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA), New Paltz, 2011, pp. 5-8.
- S. Koyama, Y. Hiwasaki, K. Furuya, and Y. Haneda, “Inverse Wave Propagation for Reproducing Virtual Source in Front of Loudspeaker Array,” in Proceedings of European Signal Processing Conference (EUSIPCO), Barcelona, 2011, pp. 1322-1326.
- S. Koyama, Y. Hiwasaki, K. Furuya, and Y. Haneda, “Inverse Wave Propagation in Wave Field Synthesis,” in Proceedings of 40th AES International Conference, Tokyo, 2010.
- S. Koyama and R. Suzuki, “Scape Synthesis: Generation of a Novel Acoustical Space Based on Auditory Perceptual Features,” in Proceedings of the 2009 International Computer Music Conference (ICMC), Montreal, 2009, pp. 533-536.
- S. Koyama, T. Kurihara, and S. Ando, “A Direct Algebraic Method of Instantaneous Wave Source Localization,” in Proceedings of SICE Annual Conference, 2008, pp. 532-537.
- S. Ando, S. Koyama, N. Ono, and N. Ikeuchi, “Silicon Cochlear Microphone “Fishbone” with Complex Filtering and Hilbert Transform Capability for Instantaneous Signal Detection and Analysis,” in Proceedings of Transducers ’07, Lyon, 2007, pp. 1295-1298.

## Invited / Seminar Talks

- Y. Takida, S. Koyama, N. Ueno, and H. Saruwatari, “Comparison of Interpolation Methods for Gridless Sound Field Decomposition Based on Reciprocity Gap Functional,” in Proceedings of International Congress on Sound and Vibration (ICSV), Montreal, 2019.
- S. Koyama, “Sparsity-based sound field reconstruction,” in Tohoku Universal Acoustical Communication Month, Seminar on the spatial aspects of hearing and their applications, keynote lecture, Sendai, 2018.
- S. Koyama, “Sparsity-Aware Sound Field Recording / Joint Source and Sensor Placement for Sound Field Control,” in Microsoft Research Lab, Redmond, seminar talk, 2018.
- S. Koyama, “Sound field recording and reproduction using small number of microphones and loudspeakers,” in University of Southampton, Institute of Sound and Vibration Research (ISVR), seminar talk, 2017.
- S. Koyama, N. Murata, and H. Saruwatari, “Effect of Multipole Dictionary in Sparse Sound Field Decomposition For Super-resolution in Recording and Reproduction,” in Proceedings of International Congress on Sound and Vibration (ICSV), London, 2017.
- S. Koyama, N. Murata, and H. Saruwatari, “Super-resolution in sound field recording and reproduction based on sparse representation,” in 5th Joint Meeting of the Acoustical Society of America and Acoustical Society of Japan, Honolulu, 2016.
- S. Koyama, “Source-Location-Informed Sound Field Recording and Reproduction: A Generalization to Arrays of Arbitrary Geometry,” in Proceedings of 2016 AES International Conference on Sound Field Control, Guildford, 2016.
- S. Koyama, A. Matsubayashi, N. Murata, and H. Saruwatari, “Sparse Sound Field Decomposition Using Group Sparse Bayesian Learning,” in Proceedings of Asia-Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA ASC), Hong Kong, 2015, p. 850–855.
- S. Koyama, “Sound Field Recording and Reproduction and Its Extension to Super-resolution,” in IEEE NZ North Section Technical seminar, University of Auckland, 2015.
- S. Koyama, “Sound Field Recording and Reproduction and Its Extension to Super-resolution,” in IEEE NZ Central Section Invited Lecture, Victoria University of Wellington, 2015.