| Akira Omoto | Last modified date：2023.12.07 |
Professor /
Department of Acoustic Design /
Faculty of Design
Papers
| 1. | Takahiro Iwami, Ken-ichi Sawai, Akira Omoto, Direction-of-arrival estimation in half-space from single sample array snapshot, The Journal of the Acoustical Society of America, https://doi.org/10.1121/10.0019550, 153, 5, 3025-3035, 2023.05, [URL], Most existing direction-of-arrival (DOA) estimation algorithms are intended for single-frequency use. However, the majority of real sound fields are wideband, and the application of these techniques then becomes computationally expensive. In this paper, a fast DOA estimation method for use with wideband sound fields is constructed from only a single observation of the array signal based on the properties of a space of spherically band-limited functions. The proposed method can be applied to any element arrangement and spatial dimensions, and the computational load is only dependent on the number of microphones in the array. However, because this method does not use time information, forward-backward identification of the arriving waves is not possible. Therefore, the proposed DOA estimation method is limited to a half-space. Numerical simulations of multiple sound waves arriving from a half-space show that the proposed method offers good processing performance when applied to pulse-like broadband sound fields. The results also indicate that the method is capable of tracking DOAs in real time, even when these DOAs vary rapidly.. |
| 2. | Ryoko Hara, Takahiro Iwami, Akira Omoto, Subjective evaluation of auralization using a directional sound source that simulates a trumpet, Acoustical Science and Technology, https://doi.org/10.1250/ast.43.166, 43, 2, 166-169, 2022.03. |
| 3. | Ryoko Hara, Takahiro Iwami, Hiroshi Kashiwazaki, Akira Omoto, Synthesis of musical instrument directivities with a single common loudspeaker (L), The Journal of the Acoustical Society of America, https://doi.org/10.1121/10.0006660, 150, 4, 2549-2552, Letter, 2021.10, [URL], This letter synthesizes musical instrument directivities by sequentially rotating a loudspeaker through multiple orientations. The synthesis is conducted in a spherical harmonic domain using the actual measured directivity of a commercial loudspeaker and an open database of musical instrument directivities. The letter further proposes a practically useful set of 26 loudspeaker orientations named Step45, which can be used to reproduce the target directivity as well as if the orientations were determined adopting mathematical methods that give equilibrium configurations.. |
| 4. | Akira Omoto, Hiroshi Kashiwazaki, Hypotheses for constructing a precise, straightforward, robust and versatile sound field reproduction system, Acoustical Science and Technology, https://doi.org/10.1250/ast.41.151, 41, 1, 151-159, Invited Review, 2020.01, The three dimensional sound field reproduction systems can be categorized mainly into two types, physical reproduction, and artistic reproduction. The former is sometimes referred to as scientific or engineering, and the latter is sometimes recognized as psychological reproduction using phantom images produced by, for example, amplitude panning and the other effects. The purpose of the reproduction system is widely spread. The system can be a design tool of enclosed space, such as a concert hall, before practical construction by reproducing physical characteristics accurately. Also, the system can be a pure entertainment tool, mostly with visual images. Of course, the scale and necessary conditions vary with their purpose and objectives; however, it might be interesting to investigate what are the essential factors for the higher total performance of reproduction systems. We currently hypothesize that the following four conditions might be necessary for the total performance of the versatile sound field reproduction system. A) physical accuracy, B) robustness against disturbance, C) flexibility for additional direction, D) capability of integration with visual stimuli. As a platform of examination, 24-channel narrow directional microphone array and 24-channel loudspeaker array are used. The boundary surface control principle and its modified version are adopted for the physical background. As examples, several practical efforts are attempted to assure the total performance of the system effectively..  |
| 5. | Hiroshi Kashiwazak, Akira Omoto, Sound field reproduction system using narrow directivity microphones and boundary surface control principle, Acoustical Science and Technology, 10.1250/ast.36.1, 39, 4, 2018.07, Boundary surface control (BoSC) is a useful method of reproducing the sound field physically. However, it is challenging in the case of real-time operation. This is mainly due to the calculation cost of a lot of inverse filter convolutions to obtain reproduction signals. This paper proposes a method for reducing of number of inverse filters and implements it in 24-channel narrow directivity (shotgun) microphone array and 24-channel circularly arranged loudspeaker array. Moreover, it provides an experimental evaluation of the reproduction accuracy according to measurement of reproduced wavefront. The accuracy of the reproduced wavefront by the filters, whose number was reduced to less than 1/5 by proposed method, was comparable with the case of full number of filters. Finally, a system aiming at sound field reproduction in a wide frequency range was constructed by a hybrid method of reproducing with an inverse filter in the low range and directly outputting from the speaker in the direction corresponding to the microphone in the high frequency range. We confirmed that real-time processing is possible for this hybrid method by using a convolution plug-in of digital audio workstation software.. |
| 6. | Akira Omoto, Shiro Ise, Yusuke Ikeda, Kanako Ueno, Seigo Enomoto, Maori Kobayashi, Sound field reproduction and sharing system based on the boundary surface control principle , Acoustical Science and Technology, 10.1250/ast.36.1, 36, 1, 1-11, 2015.01. |
| 7. | Akira Omoto, Comment on 'A theoretical framework for quantitatively characterizing sound field diffusion based on scattering and absorption coefficient of walls', Journal of the Acoustical Society of America, 10.1121/1.4768884, 133, 1, 9-12, 2013.01. |
| 8. | Yuki Matsumoto, Akira Omoto, Application of an Auditory Filter for the Evaluation of Sounds and Sound Fields, Building Acoustics, 10.1260/1351-010X.18.1-2.175, 18, 1-2, 175-188, ISRAでのポスター発表原稿が掲載されたもの, 2011.03. |
| 9. | Yuki Matsumoto, Akira Omoto, Sound Field Evaluation by Using Auditory Filter: Application of Dynamic Compressive Gammachirp Filter, Acoustical Science and Technology, 31, 5, 368-370, 2010.09. |
| 10. | Taeko Akama, Hisaharu Suzuki, Akira Omoto, Distribution of selected monaural acoustical parameters in concert halls, Applied Acoustics, 10.1016/j.apacoust.2010.01.004, 71, 6, 564-577, Vol. 28, pp.84-89, 2010.06. |
| 11. | Yasuhiko Nagatomo, Namiko Hiramatsu, Genta Yamauchi, Akira Omoto, Variable reflection acoustic wall system by active sound radiation, Acoustical Science and Technology, Vol. 28, pp.84-89, 2007.03. |
| 12. | Hisaharu Suzuki, Akira Omoto, Kyoji Fujiwara, Treatment of boundary condition by finite difference time domain method, Acoustical Science and Technology, Vol. 28, pp.16-26, 2007.01. |
| 13. | Yoshinari Fukushima, Hisaharu Suzuki, Akira Omoto, Visualization of reflected sound in enclosed space by sound intensity measurement, Acoustical Science and Technology, Vol. 27, pp.187-189, 2006.05. |
| 14. | Yoko Takenouchi, Hisaharu Suzuki, Akira Omoto, Behavior of the practically implemented filtered reference LMS algorithm in an active noise control system, Acoustical Science and Technology, Vol. 27, pp.20-27, 2006.01. |
| 15. | Atsuro Ikeda, Masataka Nakahara, Chizuru Kai, Akira Omoto, The acoustical effect of audio equipment and furniture in a mixing room, Acoustical Science and Technology, Vol. 26, pp.233-236, 2005.03. |
| 16. | Masataka Nakahara, Akira Omoto, Kyoji Fujiwara, The effect of a mixing console on the monitoring response in a mixing room, Acoustical Science and Technology, Vol. 26, pp.90-101, 2005.03. |
| 17. | Akira Omoto, Harunori Uchida, Evaluation method of artificial acoustical environment: Visualization of sound intensity, Journal of Physiological Anthropology and Applied Human Science, Vol. 23, pp.249-253, 2004.12. |
| 18. | Yoko Takenouchi, Hisaharu Suzuki, Akira Omoto, Behavior of the adaptive algorithm for non-stationary noise signal: Difference between theoretical formulation and the practical implementation, Acoustical Science and Technology, Vol. 25, No. 6, pp.489-492, 2004.11. |
| 19. | Akira Omoto, Active Noise Control: Adaptive Signal Processing and Algorithm, IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E85-A, No. 3 pp. 548-557, 2002.03. |
| 20. | Akira Omoto, Daisuke Morie, Kyoji Fujiwara, Behavior of adaptive algorithms in active noise control systems with moving noise sources, Acoustical Science and Technology, Vol. 23, No. 2 pp. 84-89, 2002.03. |
| 21. | Gensei Matsumoto, Kyoji Fujiwara, Akira Omoto, A study on the insertion loss of a noise barrier for a directional sound source, The Journal of the Acoustical Society of Japan (E), Vol. 20, No. 4, pp. 325-328, 1999.07. |
| 22. | Akira Omoto, S. J. Elliott, The Effect of Structured Uncertainty in the Acoustic Plant on Multichannel Feedforward Control Sysrtems, IEEE Transaction on Speech and Audio Processing, Vol. 7, No. 2, pp. 204-212, 1999.03. |
| 23. | Akira Omoto, Tohru Matsui, Kyoji Fujiwara, The behaviour of an adaptive algorithm with a moving primary source, The Journal of the Acoustical Society of Japan (E), Vol. 19, No. 3, pp. 211-221, 1998.05. |
| 24. | Akira Omoto, Kazuhiro Takashima, Kyoji Fujiwara, Masao Aoki, Yasuo Shimizu, Active suppression of sound diffracted by a barrier: an outdoor experiment, Journal of the Acoustical Society of America, Vol. 102, No. 3, pp. 1671-1679, 1997.09. |
| 25. | 尾本 章，S. J. Elliott, The Effect of Structured Uncertainty in Multichannel Feedforward Control Sysrtems, 1996 IEEE International Conference on Acoustics, Speech & Signal Processing, Volume 2, pp. 965-968, 1996.05. |
| 26. | Akira Omoto, Kyoji Fujiwara, A study of an actively controlled noise barrier, Journal of the Acoustical Society of America, Vol. 94, No. 4 pp. 2173-2180, 1993.10. |
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