SUGAHARA Akiko

Department of ArchitectureLecturer

Last Updated :2024/09/14

■Researcher basic information

Degree

  • Ph. D in Engineering(2020/03 The University of Tokyo)

Researcher number

90878175

Research Field

  • Social infrastructure (civil Engineering, architecture, disaster prevention) / Construction environment and equipment / room acoustics, acoustic materials

■Career

Career

  • 2020/04 - Today  Kindai UniversityFaculty of Architecture Department of ArchitectureAssistant professor

Educational Background

  • 2017/04 - 2020/03  The University of Tokyo  The Graduate School of Engineering  Department of Architecture
  • 2015/04 - 2017/03  The University of Tokyo  The Graduate School of Engineering  Department of Architecture
  • 2011/04 - 2015/03  Osaka University  School of Engineering  Division of Global Architecture

■Research activity information

Award

  • 2021/09 日本音響学会 粟屋潔学術奨励賞
     結晶構造を利用した多孔質吸音材の吸音特性に関する検討
  • 2019/10 日本騒音制御工学会 研究奨励賞
     パラメトリックスピーカを用いた斜入射吸音率の現場測定
  • 2018/10 日本騒音制御工学会 学生優秀発表賞
     パラメトリックスピーカを用いた斜入射吸音率の現場測定
  • 2018/09 日本建築学会 環境工学部門若手優秀発表賞
     パラメトリックスピーカを用いた材料音響特性のin-situ測定
  • 2016/03 日本音響学会 学生優秀発表賞
     パラメトリックスピーカを用いた板の反射特性計測の試み

Paper

  • Yudai Yamashiro; Kazunori Harada; Akiko Sugahara; Yasuhiro Hiraguri; Takuya Oshima; Yoshinori Saito; Satoshi Atobe
    日本音響学会誌 79 (3) 140 - 147 2023/03 [Refereed]
  • 岡村 健太郎; 腰原 幹雄; 安井 昇; 今本 啓一; 大塚 亜希子; 加來 千紘; 本間 健太郎; 林 憲吾; 菅原 彬子
    住総研研究論文集・実践研究報告集 49 73 - 84 2023/03 [Refereed]
  • Akiko SUGAHARA; Yasuhiro HIRAGURI; Ichizo KISHIMOTO
    Journal of Structural and Construction Engineering (Transactions of AIJ) Architectural Institute of Japan 87 (802) 1093 - 1103 1340-4202 2022/12 [Refereed]
  • Kohei Yatabe; Akiko Sugahara
    Applied Acoustics Elsevier BV 199 108988 - 108988 0003-682X 2022/10 [Refereed]
     
    Numerical simulation of impulse responses is an important task for room acoustic design and prediction. Since an impulse response is a concept in the time domain, time-domain simulation methods are popular for this task. At the same time, frequency-domain simulation methods are also used for simulating a room impulse response by computing frequency responses and applying the inverse discrete Fourier transform (IDFT). In this case, well-established frequency-domain solvers, including finite element method (FEM) and boundary element method (BEM), can be used. However, IDFT generates some artifacts that are undesirable for room acoustic evaluation. If such artifacts can be attenuated, then the frequency-domain methods become more attractive for simulating room impulse responses. In this paper, we propose a post-processing method to attenuate the artifacts from the impulse responses computed by the combination of frequency-domain simulation and IDFT. It is formulated as a convex optimization problem, and the alternating direction method of multipliers (ADMM) is applied to obtain the solution. Numerical experiments confirmed that the proposed method can effectively reduce the undesirable artifacts from the reconstructed impulse responses. An example implementation of the proposed method in MATLAB is provided at https://doi.org/g9h5.
  • Akiko Sugahara
    Acoustical Science and Technology Acoustical Society of Japan 43 (5) 251 - 259 1346-3969 2022/09 [Refereed]
  • 長崎県端島における打音法を用いたRC柱の劣化調査
    菅原彬子; 赤石全; 大磯朱音; 平栗靖浩
    コンクリート工学年次論文集 44 (1) 1342 - 1347 2022/07 [Refereed]
  • Akiko Sugahara; Kohei Okubo; Miki Yonemura; Hyojin Lee; Shinichi Sakamoto; Yuichi Yonemoto; Toshiya Ohshima
    Acoustical Science and Technology Acoustical Society of Japan 42 (4) 202 - 205 1346-3969 2021/07 [Refereed][Invited]
  • In-situ measurements of the deterioration of reinforced concrete buildings on Hashima island using the hammering method
    Akiko Sugahara; Ichizo Kishimoto; Yasuhiro Hiraguri
    "Advances in Acoustics, Noise and Vibration - 2021" Proceedings of the 27th International Congress on Sound and Vibration, ICSV 2021 Silesian University Press 2021 
    On Hashima Island (commonly known as Gunkanjima) in Nagasaki, Japan, where Hashima Coal Mine was formally approved as a part of the World Heritage Site, there are many reinforced concrete (RC) structures constructed several decades to a century ago. Continuous evaluation of their deterioration properties generates data regarding historic buildings and helps understand the progress of deterioration in RC buildings. A visual inspection (VI) is generally used for deterioration surveys however, determining the internal deterioration using this method alone is difficult. In this study, the hammering method is used, which analyzes the acoustic characteristics of impact echoes to determine the deterioration condition. The impact sound on the concrete surface is analyzed and compared with the VI results to improve the deterioration investigation accuracy. A steel ball impacts the columns of RC buildings, and the radiated sound from the concrete surface is recorded using a microphone. Next, the sound pressure level at the maximum amplitude of the impact sound is obtained. The above levels are compared with the VI results in general, the worse the visual results, the louder are the levels. On the other hand, although visual results are suitable, some data have higher sound pressure levels. According to a 1/3 octave band analysis, the data having similar sound pressure levels show similar frequency characteristics regardless of the visual results, indicating that such data have similar deterioration properties. These results show that the hammering method can provide information regarding the deterioration of the RC buildings on Hashima that cannot be obtained via the VI alone.
  • Kengo Togashi; Akiko Sugahara; Yasuhiro Nagasawa; Yasuhiro Hiraguri; Kazunori Harada; Kentaro Suga; Aya Onoe
    Proceedings of INTER-NOISE 2021 - 2021 International Congress and Exposition of Noise Control Engineering The Institute of Noise Control Engineering of the USA, Inc. 2021 
    The use of open-plan offices is increasing as they are effective in improving intellectual productivity by fostering communication among workers. Previous research on the relationship between the indoor sound environment and intellectual productivity has mostly reported the impact of the sound environment on the tasks that individuals work on. However, there has been little research on the impact of sound environments on office spaces where multiple workers are actually working. In this research, we developed a system that can analyze the individual characteristics of workers concerning the sound environment by simultaneously measuring their impression evaluation against the sound environment and the sound environment in the office. The system collects workers' impression evaluation against the sound environment through a regular questionnaire using the experience sampling method. At the same time, it measures the sound environment in the office with multiple small measurement devices. The obtained sound environment evaluation data and the acoustic data in the office were uploaded onto the Web server as a single database.
  • Itsuki Ikemi; Kazunori Harada; Akiko Sugahara; Yasuhiro Hiraguri
    Proceedings of INTER-NOISE 2021 - 2021 International Congress and Exposition of Noise Control Engineering The Institute of Noise Control Engineering of the USA, Inc. 2021 
    The sounds from childcare facilities are often a cause of noise problems with neighbors. However since the sound power levels of children's play and other sounds in child-care facilities have not become clear, evaluation methods have not been established, making countermeasures difficult. In order to evaluate the noise, it is necessary to model the location of the sound source and the sound power level. We have been developing a sound source identification system that uses multiple Raspberry Pi-based recording devices to estimate the location of a sound source and sound power levels. By using GPS for time synchronization, the system can be distributed and placed without connecting cables, which is expected to expand the measurement area significantly. As a method of estimation, the arrival time difference is calculated by cross-correlation from the signals input to each recording device, and the sound source location is estimated from the calculated arrival time difference and the location information of the device. The effectiveness of this system was verified in an anechoic chamber and outdoor fields.
  • 駅コンコースにおける音環境評価のための実測調査および聴感評価実験
    李孝珍; 坂本慎一; 菅原彬子; 池田佳樹
    日本建築学会環境系論文集 84 (765) 983 - 992 2019/11 [Refereed]
  • Akiko Sugahara; Hyojin Lee; Shinichi Sakamoto; Shigeto Takeoka
    Applied Acoustics ELSEVIER SCI LTD 152 54 - 62 0003-682X 2019/09 [Refereed]
     
    When measuring the acoustic properties of architectural materials in a free field or in situ, reflections from the surroundings of the target material and diffraction from the sample edges often generate significant measurement errors. In this paper, a method for measuring acoustic properties by using a parametric loudspeaker, which is superdirective due to the nonlinearity of superhigh-pressure ultrasound, is proposed to overcome this problem: its strong directivity can reduce undesired waves by focusing the sound onto a narrow spatial range. However, such a superstrong ultrasound generates pseudo sound on the microphone surface and increases the measurement errors. Hence, two different strategies, acoustic filtering via phononic crystals and phase-cancellation excitation of the ultrasound, are experimentally investigated to reduce such induced errors. They are also used to evaluate the surface impedance of glass-wool boards at oblique incidence is measured in a free field and in situ. The results show that the proposed method can efficiently measure the surface impedance at frequencies higher than 800 Hz. (C) 2019 Elsevier Ltd. All rights reserved.
  • In-situ measurement of acoustic impedance at oblique incidence by using a parametric loudspeaker
    Akiko Sugahara; Hyojin Lee; Shinichi Sakamoto; Shigeto Takeoka
    Proceedings of the 26th International Congress on Sound and Vibration, ICSV 2019 Canadian Acoustical Association 2019 
    Acoustic measurements of an architectural material in a free field or in-situ are influenced by diffraction from sample edges and reflections from other room boundaries. These undesired waves may cause a measurement error. Especially, a measurement at oblique incidence is quite difficult as the incident angle is larger or the sample size is smaller. In this study, a parametric loudspeaker, which is super-directive by utilizing the nonlinearity of ultrasound, is used to overcome the difficulty. The parametric loudspeaker can reduce the undesired waves by focusing the incident sound onto a small spatial range and will be used as a simple and accurate measurement method. However, the super strong ultrasound used as the source signal causes the nonlinear distortion called "pseudo sound" on the microphone surface and increases the measurement errors. In order to minimize such induced errors, two methods are investigated experimentally: acoustic filtering via phononic crystals and the phase-cancellation excitation of the ultrasound. In our previous work, acoustic impedance of a glass-wool board at oblique incidence is measured using these two methods in an anechoic chamber. The results show that the proposed method is effective at frequencies above 800 Hz in a free field. Based on this, in the presented study, in-situ measurements are conducted in a conference room. This investigation shows that the proposed method can efficiently estimate the acoustic impedance at oblique incidence in-situ at frequencies above 800 Hz
  • Hyojin Lee; Shinichi Sakamoto; Akiko Sugahara; Yoshiki Ikeda
    Journal of Environmental Engineering (Japan) Architectural Institute of Japan 84 (765) 983 - 991 1881-817X 2019 
    Most railway stations of Japan finished with materials of good durability and fire resistance, causing insufficient sound absorption. This implies that background noise is loud and announcements are unclear. We conducted a field survey and a subjective experiment focusing on listening difficulty From the result, the background noise ranged 65"/0 dB and the announcements were higher than background noise. However the difference did not exceed 10 dB at most measurement points. When the level difference of the announcement and the background noise was +10 dB, about 29 % of subjects reported the female announcement difficult to hear and 50% reported the male announcement difficult to hear.
  • A study on in-situ method of measuring acoustic properties of materials by using a parametric loudspeaker -Reduction of pseudo sound due to high pressure ultrasound-
    Akiko Sugahara; Hyojin Lee; Shinichi Sakamoto; Shigeto Takeoka
    INTER-NOISE 2018 - 47th International Congress and Exposition on Noise Control Engineering: Impact of Noise Control Engineering Institute of Noise Control Engineering 2018 
    When measuring surface acoustic impedance and/or absorption coefficient of architectural materials in-situ, interference between the reflection from the target area and the undesired waves, such as reflection from other boundaries and diffraction from sample edge, often causes serious measurement error. The authors have investigated a measurement method of these properties using a parametric loudspeaker, which produces a sharp audible sound beam by the nonlinear-interaction of ultrasound, to minimize such harmful effects. Its strong directivity may reduce the undesired waves by making the sound incident onto the small spatial range. However, the super high sound pressure ultrasound causes “pseudo sound” on the microphone surface, and increases error in the results, especially in lower frequency range. In this study, two methods, phase-cancellation method and application of acoustic filter with phononic crystals, were verified experimentally to eliminate the pseudo sound. As a fundamental investigation, the reduction effect of the two methods against the pseudo sound was verified in a free field measurement. Regarding acoustical property measurement, surface impedance and absorption coefficient of glass-wool boards were measured applying the two methods in an ordinary room. The results showed good agreement with those measured by the impedance tube method for frequencies higher than 1 kHz.
  • Akiko Sugahara; Hisahi Kotani; Yoshihisa Momoi; Toshio Yamanaka; Kazunobu Sagara; Risa Fujiwara
    INTERNATIONAL JOURNAL OF VENTILATION TAYLOR & FRANCIS LTD 16 (3) 163 - 173 2017/04 [Refereed]
     
    The air-cooled packaged air-conditioner, widely used in small and medium buildings, needs the large number of outdoor units to apply various room conditions. Its operating efficiency can be changed by the high distribution density of the units and some other installations. This study aims to propose an optimum configuration of building installation at the rooftop by providing a better wind environmental condition for the energy saving. Thus, it is necessary to predict the airflow field around the rooftop. First, the airflow field around the rooftop was investigated by the Particle Image Velocimetry using scale models. The positional relation between the devices showed a sensible effect on the airflow characteristics. Moreover, the experimental data was compared with that of the Computational Fluid Dynamics (CFD) analysis to evaluate the accuracy of the calculation. They are similar to be said that CFD can represent the real situation approximately.
  • A study on the measurement of the absorption coefficient by using a parametric loudspeaker
    Akiko Sugahara; Hyojin Lee; Shinichi Sakamoto; Shigeto Takeoka
    INTER-NOISE 2017 - 46th International Congress and Exposition on Noise Control Engineering: Taming Noise and Moving Quiet Institute of Noise Control Engineering 2017- 2017 
    The acoustic properties of architectural materials, such as the absorption coefficient and the acoustic impedance, are the important elements when considering the acoustic performances of rooms. Measured results of these parameters in a free field and in-situ situation are often affected by undesired waves due to the diffraction from sample edge and reflection from other boundaries. A parametric loudspeaker, which produces a sharp audible sound beam by the nonlinear interaction of ultrasound beams, was used to minimize such influences in this study. At first, the radiation directivity of a parametric loudspeaker was measured and its strong directivity was confirmed. To verify this method for in-situ measurement, the proposed method was applied to a measurement in a conference room. The parametric loudspeaker could reduce the effect of the diffraction from the sample edge and reflection from other boundaries, although the measurement accuracy was decreased in the low frequency range less than 1.5 kHz. The measurements using a parametric loudspeaker might be affected by a pseudo sound, which is a spurious signal generated by the nonlinearity of the ultrasound. Then, two methods were investigated to reduce this effect and to propose a suitable measurement method using the parametric loudspeaker. The measurement accuracy of the absorption coefficient at normal incidence was improved with the method in an anechoic chamber.

MISC

Lectures, oral presentations, etc.

  • A study on normal incident sound absorption characteristics of Japanese traditional cedar board, yakisugi  [Not invited]
    Akiko Sugahara; Yasuhiro Hiraguri; Kentaro Okamura; Noboru Yasui; Chihiro Kaku
    Inter-Noise 2022, Glasgow
  • In-situ measurement ofacoustic impedance at oblique incidence by using a paametric loudspeaker  [Not invited]
    Akiko Sugahara; Hyojin Lee; Shinichi Sakamoto; Shigeto Takeoka
    The 26th International Congress on Sound and Vibration
  • A Study on In-Situ Method of Measuring Acoustic Properties of Materials by using a Parametric Loudspeaker - Reduction of Pseudo Sound due to High Pressure Ultrasound
    Akiko Sugahara; Hyojin Lee; Shinichi Sakamoto; Shigeto Takeoka
    Inter-Noise 2018, Chicago
  • Environment of railway station by field measurement and subjective experiment  [Not invited]
    Hyojin Lee; Akiko Sugahara; Shinichi Sakamoto; Yoshiki Ikeda
    Inter-Noise 2018, Chicago
  • A study on the measurements of the absorption coefficient by using a parametric loudspeaker  [Not invited]
    Akiko Sugahara; Hyojin Lee; Shinichi Sakamoto; Shigeto Takeoka
    Inter-Noise 2017, Hong Kong

Research Themes

  • 日本学術振興会:科学研究費助成事業 若手研究
    Date (from‐to) : 2022/04 -2027/03 
    Author : 菅原 彬子
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    Date (from‐to) : 2022/04 -2025/03 
    Author : 坂本 慎一; 菅原 彬子; 米村 美紀
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research
    Date (from‐to) : 2020/09 -2022/03 
    Author : Sugahara Akiko
     
    In this study, some micro-periodic structures using naturally occurring crystal structures and simple resonators as unit cells were designed. Their sound absorption characteristics at normal incidence were investigated by finite element analysis and experimental investigation of 3D-printed objects. The results suggest that parameter tuning of the unit cells enables various sound absorption characteristics. It is also found that a resonator-type unit cell with grids have stable and high sound absorption for low- and middle-frequency ranges. These findings suggest that the proposed structures lead to a good sound absorber with the desired characteristics depending on the situation.
  • 日本学術振興会:科学研究費助成事業 特別研究員奨励費
    Date (from‐to) : 2017/04 -2020/03 
    Author : 菅原 彬子
     
    本研究は、建築材料の音響特性を高精度に計測し、3次元の音響シミュレーションシステムを開発するという最終目標に向けて、鋭い放射指向性をもつパラメトリックスピー カを音源として用いた吸音特性の測定法の開発を行うものである。その狭指向性により音波を材料に局所的に入射することで、不要な反射や回折の影響を低減し、従来の測定法で困難であった条件でも計測が可能となる、汎用的な測定法となることが期待される。 パラメトリックスピーカを用いて可聴音を計測するためには、音源信号として用いる高音圧な超音波が受音系統で引き起こす、擬音とよばれる局所歪、およびそれに起因する計測誤差を低減する必要がある。そこで、受音点付近での超音波の音圧を低減することを考えた。まず、音源信号として位相反転信号を用いる信号処理的な制御、及びフォノニック結晶と呼ばれる物理フィルタを用いた構造的な制御により、この課題を解決した。 次に、吸音材料として一般的に用いられる多孔質吸音材を対象に、垂直入射吸音特性の計測を行ったところ、2つの手法を用いることで、擬音の影響による計測誤差が低減できた。 また、位相反転駆動方式では、超音波の低減領域が非常に狭く、特に入射角が大きい場合で受音点をその領域内に設置することが困難であった。しかし、その駆動方式に更なる改良を加えた結果、どの角度においても精度よく測定を行うことができた。 以上の検討より、音源信号の位相反転駆動、またはフォノニック結晶をパラメトリックスピーカの狭指向性に組み合わせることで、不要な反射や回折、擬音の影響を低減し、従来困難であった入射角が大きい場合や試料サイズが比較的小さい場合にも、計測が可能となることを確認した。