Akira Omoto | Kyushu University (original) (raw)
Papers by Akira Omoto
NOISE-CON ... proceedings, Nov 29, 2023
Eizō Jōhō Media Gakkaishi, 2011
Technical report of IEICE. EA, Nov 26, 1993
Acoustical Science and Technology, Jul 1, 2018
Journal of the Acoustical Society of America, Sep 1, 1997
IEICE Technical Report; IEICE Tech. Rep., Nov 13, 2014
Acoustical Science and Technology, Oct 1, 2006
Journal of the Acoustical Society of America, Oct 1, 2016
Sound field reproduction system can be categorized roughly into two types. The first is physicall... more Sound field reproduction system can be categorized roughly into two types. The first is physically assured system which reproduce the wavefront or another physical parameters by engineering means. Typical examples are the boundary surface control system, the wave field synthesis, the ambisonics, and so on. The second type is a psychological system that reproduces phantom images one sound at any desired position by artificial manipulation with rather simple technique such as volume based amplitude panning. Examples are the two channel stereo system and the surround system using 5.1 or more loudspeakers. The latter can be recognized as somewhat “artistic” method, because it requires norms based on artistic sense. The present study aims to fuse the engineering and artistic systems mentioned above. The boundary surface control system, which consists of 24-channel narrow directional microphones and 24 channel loudspeakers, was used as the platform of research. Based on the conventional control technique using inverse filtering, additional manipulation such as simple reproduction scheme for high frequency was introduced. Also, the concept of variable reflection acoustic wall system, which adds the artificial reverberation to the sounds that listener makes, was involved in the reproduction system for the direction of the presence.
Journal of the Acoustical Society of America, Oct 1, 1996
Because of the rapid progress of DSP hardware performance, the application of active noise contro... more Because of the rapid progress of DSP hardware performance, the application of active noise control to a moving noise source has become a much more realistic problem. This study describes the preliminary investigations concerning the behavior of a multichannel adaptive algorithm with a moving primary source. The steepest descent algorithms, such as multiple error filtered-x LMS, are often used in practical feedforward active control applications. A previous study showed that the stability and the performance of this algorithm strongly depend on the estimation errors of the transfer responses of the acoustic plant being controlled. The effect of the primary signal variations including the Doppler effect, however, had hardly been investigated. In this study, the convergence properties of the algorithms with the moving sound source were examined by numerical simulations. To simplify the problems and clarify the substantial limitations of the system, a pure tone and a simple free field was assumed as the primary signal and the sound field, respectively. Results showed that the system could converge, and the possible attenuation was varied corresponding to the positions of the primary source.
Journal of the Acoustical Society of America, Nov 1, 2006
For acoustic design of special spaces such as studios, it might be necessary to realize a diffuse... more For acoustic design of special spaces such as studios, it might be necessary to realize a diffuse reflection from the specific wall surface. Moreover, this requirement often changes according to the time or situation. In this study, a new acoustic wall system is examined; it is a variable reflection acoustic wall system that can address such strict requirements. This system fundamentally comprises a loudspeaker, a pick-up microphone, and absorbent material. Varying the amplitude of the radiation sound that is picked up by the microphone and reradiated by the loudspeaker mounted behind the absorbing material therefore corresponds to varying the reflection performance of the wall system. Several models are proposed. The measurement results show that the proposed models can realize various absorption characteristics. Additionally, these models can realize various radiation characteristics: diffuse reflection and inclined reflection to a desired direction. Furthermore, the frequency characteristic of simulated radiation is changed, so the proposed system can generate reflection coefficient with intended frequency characteristics. The design of an effective feedback canceller between the pick-up microphones is the subject of ongoing research toward practical use of this proposed system.
Building Acoustics, Jun 1, 2014
Acoustical Science and Technology, 2005
Journal of Physiological Anthropology and Applied Human Science, 2004
NOISE-CON ... proceedings, Nov 29, 2023
Nippon Onkyo Gakkaishi/Acoustical science and technology/Nihon Onkyo Gakkaishi, Mar 1, 2024
Acoustic intensity estimation is an important research topic in the field of architectural acoust... more Acoustic intensity estimation is an important research topic in the field of architectural acoustics. Various point-based intensity estimation methods using microphone probes have been proposed so far. On the other hand, research has also been conducted on average acoustic intensity field estimation methods using microphone arrays. This study proposes a method for estimating instantaneous sound intensity fields that can be applied to arbitrary spatial dimensions and array configurations. The proposed method is based on representing the instantaneous sound field using the reproducing kernel of a space of spherically band-limited functions. One of the key advantages of the proposed is its ability to analytically handle the spatial differentiation involved in the calculation of particle velocities, allowing for more accurate intensity estimation compared to the p-p method. Numerical simulations were conducted to validate the effectiveness of the proposed method, using a three-dimensional plane wave sound field.
日本音響学会研究発表会講演論文集, Mar 8, 2005
Presentation slides at Forum Acusticum 2014
NOISE-CON ... proceedings, Nov 29, 2023
Eizō Jōhō Media Gakkaishi, 2011
Technical report of IEICE. EA, Nov 26, 1993
Acoustical Science and Technology, Jul 1, 2018
Journal of the Acoustical Society of America, Sep 1, 1997
IEICE Technical Report; IEICE Tech. Rep., Nov 13, 2014
Acoustical Science and Technology, Oct 1, 2006
Journal of the Acoustical Society of America, Oct 1, 2016
Sound field reproduction system can be categorized roughly into two types. The first is physicall... more Sound field reproduction system can be categorized roughly into two types. The first is physically assured system which reproduce the wavefront or another physical parameters by engineering means. Typical examples are the boundary surface control system, the wave field synthesis, the ambisonics, and so on. The second type is a psychological system that reproduces phantom images one sound at any desired position by artificial manipulation with rather simple technique such as volume based amplitude panning. Examples are the two channel stereo system and the surround system using 5.1 or more loudspeakers. The latter can be recognized as somewhat “artistic” method, because it requires norms based on artistic sense. The present study aims to fuse the engineering and artistic systems mentioned above. The boundary surface control system, which consists of 24-channel narrow directional microphones and 24 channel loudspeakers, was used as the platform of research. Based on the conventional control technique using inverse filtering, additional manipulation such as simple reproduction scheme for high frequency was introduced. Also, the concept of variable reflection acoustic wall system, which adds the artificial reverberation to the sounds that listener makes, was involved in the reproduction system for the direction of the presence.
Journal of the Acoustical Society of America, Oct 1, 1996
Because of the rapid progress of DSP hardware performance, the application of active noise contro... more Because of the rapid progress of DSP hardware performance, the application of active noise control to a moving noise source has become a much more realistic problem. This study describes the preliminary investigations concerning the behavior of a multichannel adaptive algorithm with a moving primary source. The steepest descent algorithms, such as multiple error filtered-x LMS, are often used in practical feedforward active control applications. A previous study showed that the stability and the performance of this algorithm strongly depend on the estimation errors of the transfer responses of the acoustic plant being controlled. The effect of the primary signal variations including the Doppler effect, however, had hardly been investigated. In this study, the convergence properties of the algorithms with the moving sound source were examined by numerical simulations. To simplify the problems and clarify the substantial limitations of the system, a pure tone and a simple free field was assumed as the primary signal and the sound field, respectively. Results showed that the system could converge, and the possible attenuation was varied corresponding to the positions of the primary source.
Journal of the Acoustical Society of America, Nov 1, 2006
For acoustic design of special spaces such as studios, it might be necessary to realize a diffuse... more For acoustic design of special spaces such as studios, it might be necessary to realize a diffuse reflection from the specific wall surface. Moreover, this requirement often changes according to the time or situation. In this study, a new acoustic wall system is examined; it is a variable reflection acoustic wall system that can address such strict requirements. This system fundamentally comprises a loudspeaker, a pick-up microphone, and absorbent material. Varying the amplitude of the radiation sound that is picked up by the microphone and reradiated by the loudspeaker mounted behind the absorbing material therefore corresponds to varying the reflection performance of the wall system. Several models are proposed. The measurement results show that the proposed models can realize various absorption characteristics. Additionally, these models can realize various radiation characteristics: diffuse reflection and inclined reflection to a desired direction. Furthermore, the frequency characteristic of simulated radiation is changed, so the proposed system can generate reflection coefficient with intended frequency characteristics. The design of an effective feedback canceller between the pick-up microphones is the subject of ongoing research toward practical use of this proposed system.
Building Acoustics, Jun 1, 2014
Acoustical Science and Technology, 2005
Journal of Physiological Anthropology and Applied Human Science, 2004
NOISE-CON ... proceedings, Nov 29, 2023
Nippon Onkyo Gakkaishi/Acoustical science and technology/Nihon Onkyo Gakkaishi, Mar 1, 2024
Acoustic intensity estimation is an important research topic in the field of architectural acoust... more Acoustic intensity estimation is an important research topic in the field of architectural acoustics. Various point-based intensity estimation methods using microphone probes have been proposed so far. On the other hand, research has also been conducted on average acoustic intensity field estimation methods using microphone arrays. This study proposes a method for estimating instantaneous sound intensity fields that can be applied to arbitrary spatial dimensions and array configurations. The proposed method is based on representing the instantaneous sound field using the reproducing kernel of a space of spherically band-limited functions. One of the key advantages of the proposed is its ability to analytically handle the spatial differentiation involved in the calculation of particle velocities, allowing for more accurate intensity estimation compared to the p-p method. Numerical simulations were conducted to validate the effectiveness of the proposed method, using a three-dimensional plane wave sound field.
日本音響学会研究発表会講演論文集, Mar 8, 2005
Presentation slides at Forum Acusticum 2014