가톨릭학교 전례 공간의 음향성능 개선 및 음향심리분석

윤영은 원광대학교 일반대학원 2022 국내박사

Catholic schools give religious education as well as a regular curriculum to deliver a religious ideology to students and make them religious. So they are required to have a place for liturgy, unlike general high schools; however, most Catholic schools have no separate place for liturgy but give a mass and religious activity in a hall or a multi-purpose place, which leads to exposure to a lot of acoustic defects. For this reason, while most of the catholic schools are trying to secure a place for liturgy by remodeling the existing space, there are little research and materials related to this issue; while the focus has been placed only on facility improvement and physical acoustic performance, the additional need to assess satisfaction with subjective acoustic performance felt by students and priests is suggested to reflect in the improvement of acoustic performance. From this perspective, this study measured acoustic performance for any acoustic defect and problem in the liturgy places of Haesung High School, Sungsim Girls' High School, and Daegeon High School, all of which are Catholic schools representing the Honam and Chungcheong areas; on this basis, acoustic simulation was used to present acoustic performance for an optimized liturgy place. Then, the changes in satisfaction with and responses to subjective acoustic performance following the improvement in physical acoustic performance were determined through psycho-acoustic experiment using auralization on the basis of the data concerning the improvement in physical acoustic performance. This study obtained the following results: 1. As for acoustic performance of the three liturgy places for catholic schools before the improvement in acoustic performance, SPL500Hz was 66.7∼68.1 dB, SPLdB(A) was 75.8∼77.0dB(A), RT500Hz was 0.58∼2.52sec, D50,500Hz was 27.7∼77.2%, C80,500Hz was –2.07∼9.07dB, and RASTI was 49.2-73.8%. This demonstrates that the pre-improvement liturgy places were characterized by such acoustic defects as excessive volume and reverberation, dry sound, extremely low clarity, and distorted original sound; therefore, it is necessary to improve them. 2. When acoustic simulation was used to improve the absorption elements within the liturgy places, the approximate adjustment was as follows: the mean absorption coefficient () of +0.04, room constant (R) of +209m2, and absorbing power (A) of +122m2 for Haesung High School, the mean absorption coefficient () of -0.13, room constant (R) of -198m2, and absorbing power (A) of -79m2 for Sungsim Girls' High School, and the mean absorption coefficient () of +0.1, room constant (R) of +442m2, and absorbing power (A) of +257m2 for Daegeon High School. So the liturgy places can be improved to have optimized acoustic performance by replacing the interior finishing materials, not by changing the plane or form of the places. 3. As for acoustic performance of the three liturgy places for the catholic schools after the improvement in acoustic performance, SPL500Hz was 64.4∼73.1dB, SPLdB(A) was 67.9∼82.3dB(A), RT500Hz was 1.44∼2.04sec, D50,500Hz was 33.0∼44.6%, C80,500Hz was –0.80∼1.03dB, and RASTI was 52.0∼57.7%. So the liturgy places with acoustic defects have been changed to have sufficient volume, proper reverberation, high definition, and full tone and become suitable for gathering activities, such as Mass, as well as for hymn-singing and other musical events. 4. The psycho-acoustic experiment showed that before the improvement in acoustic performance, excessive reverberation occurred with reverberation time of approx. 2.46 to 2.52 sec and high responsiveness to such vocabularies as reverberant and loud for Haesung High School and Daegeon High School and short reverberation time of approx. 0.58 sec led to high responsiveness to such vocabularies related to definition as definite and vivid for Sungsim Girls' High School. However, the result of the psycho-acoustic experiment following the improvement in acoustic performance is opposite to the pre-improvement result, demonstrating the differences in subjective response and changes felt by people within the liturgy places. 5. As for the improvement in the SD scale for each vocabulary after the improvement in acoustic performance in the psycho-acoustic experiment, such elements as reverberant and loud decreased by -11.3 to -17.0% while definite, vivid, intimate, warm, stable, and religious increased to 9.7 to 21.3% for Haesung High School and Daegeon High School with relatively long reverberation time. In contrast, such elements as definite and vivid decreased to –5.2 to -8.9% while reverberant, loud, intimate, warm, stable, and religious increased by 10.6 to 20.4% for Sungsim Girls' High School with short reverberation time. That is, the improvement in physical acoustic performance is accompanied by the improvement in subjective acoustic performance. 6. As for the responses to each vocabulary after the improvement in acoustic performance in the psycho-acoustic experiment, such elements as reverberation and volume decreased and definition and religiousness increased for Haesung High School and Daegeon High School with long reverberation time. In contrast, the element of definition decreased and reverberation, volume, and religiousness increased for Sungsim Girls' High School with short reverberation time. Therefore, since the improvement in acoustic performance can make differences in subjective responses felt by people, it is necessary to take both elements into account in evaluating acoustic performance. 가톨릭학교는 학교의 정규적인 교육방침과 더불어 종교적인 교육을 시행하여 종교적인 이념을 학생들에게 가르치고 신앙심을 가지도록 교육하고 있다. 그러므로 일반 고등학교와는 다르게 전례(Liturgy) 공간을 마련하는 것이 필수적 사항이지만 대부분의 가톨릭학교에서는 별도의 전례공간 없이 강당이나 다목적의 장소에서 미사와 종교활동 등이 이루어지고 있어 여러가지 음향적 결함들에 방해받고 있다. 따라서 가톨릭학교에서는 대부분 기존공간을 리모델링하여 전례공간을 확보할려고 하고 있으나 이에 대한 연구와 자료들이 부족하고 지금까지는 시설 개선 및 물리적 음향성능 확보에만 초점을 맞추었으나 향후 학생 및 신부님들이 느끼는 주관적 음향성능에 대한 만족도도 함께 평가하여 음향성능 개선에 반영해야 한다는 의견이 제시되고 있다. 해당 연구에서는 호남과 충청의 대표적인 가톨릭학교인 해성고등학교, 성심여자고등학교, 대건고등학교의 전례공간을 대상으로 음향성능을 측정하여 음향적 결함 및 문제점을 파악하였으며, 이를 토대로 음향시뮬레이션을 이용하여 최적화된 전례공간의 음향성능을 제안하였다. 이후 물리적 음향성능 개선에 따른 자료를 바탕으로 가청화 기법을 기반으로 청감실험을 진행하여 물리적인 음향성능의 개선에 따라 주관적인 음향성능에 대한 만족도와 반응의 차이를 파악하였다. 해당 연구에 대한 결과는 아래와 같다. 1. 음향성능 개선 전 가톨릭학교 전례공간 3곳의 음향성능은 SPL500Hz는 66.7∼68.1dB, SPLdB(A)는 75.8∼77.0dB(A), RT500Hz는 0.58∼2.52초, D50,500Hz는 27.7∼77.2%, C80,500Hz는 -2.07∼9.07dB, RASTI는 49.2∼73.8%였다. 따라서 개선 전 전례공간은 음량이 너무 크고 음이 과도하게 울리거나 건조하게 들리며 명료도가 매우 낮아 원음이 왜곡되어 들리는 등의 음향적인 결함이 나타나고 있어 이에 관련한 대책이 필요하다. 2. 음향시뮬레이션을 사용하여 전례공간 내부의 흡음요소를 개선하면 해성고등학교의 평균흡음률()은 +0.04, 실정수(R)는 +209m2, 흡음력(A)은 +122m2, 성심여자고등학교는 평균흡음률()은 -0.13, 실정수(R)는 -198m2, 흡음력(A)은 -79m2, 대건고등학교는 평균흡음률()은 +0.1, 실정수(R)는 +442m2, 흡음력(A)은 +257m2 정도 조정할 수 있었다. 따라서 전례공간의 평면 및 형태를 바꾸지 않아도 전례공간 내부의 마감재료만을 변경함으로써 최적화된 음향성능을 갖는 전례공간으로 개선할 수 있다. 3. 음향성능 개선 후 가톨릭학교 전례공간 3곳의 음향성능은 SPL500Hz는 64.4∼73.1dB, SPLdB(A)는 67.9∼82.3dB(A), RT500Hz는 1.44∼2.04초, D50,500Hz는 33.0∼44.6%, C80,500Hz는 -0.80∼1.03dB, RASTI는 52.0∼57.7%로 개선되었다. 따라서 개선 전 음향적 결함이 발생한 전례공간은 개선 후 충분한 음량, 적당한 울림, 명확한 명료성, 풍부한 음색 등을 갖춘 전례공간으로 바뀌었으며 미사 등의 집회활동과 성가 및 각종 음악행사에 적합한 전례공간으로 개선되었다. 4. 청감실험을 통해 음향성능 개선 전 해성고등학교와 대건고등학교는 2.46∼2.52초 정도의 긴 잔향시간으로 과도한 울림이 발생해 평가어휘 중 “울려 퍼지다”, “크다”에 대한 반응이 높게 나타났으나 0.58초 정도의 짧은 잔향시간을 갖고 있는 성심여자고등학교는 명료성과 관련된 어휘인 “분명하다”, “생생하다”에 대한 반응이 높게 나타났다. 그러나 음향성능 개선 후 청감실험 결과는 개선 전과 반대로 나타나 음향성능을 개선함으로써 전례공간 내부에서 사람들이 느끼는 주관적 반응 및 변화도 다르게 나타남을 알 수 있다. 5. 청감실험을 통해 음향성능 개선 전·후의 평가어휘별 SD척도의 개선량을 분석해 보면 비교적 잔향시간이 길었던 해성고등학교와 대건고등학교는 “울려 퍼지다”, “크다” 등 의 요소는 -11.3∼-17.0% 감소하였으나 “분명하다”, “생생하다”, “친밀감 있다”, “포근하다”, “안정감 있다”, “경건하다”는 9.7∼21.3%로 증가하였다. 그러나 잔향시간이 짧았던 성심여자고등학교는 “분명하다”, “생생하다”의 요소는 -5.2∼-8.9%로 감소하였으며, “안정감 있다”, “크다”, “울려 퍼지다”, “포근하다”, “친밀감 있다”, “경건하다”는 10.6∼20.4% 증가하였다. 따라서 물리적 음향성능이 개선되면 사람들이 느끼는 주관적 음향성능도 개선됨을 알 수 있다. 6. 청감 실험을 통해 음향성능 개선 전‧후 평가어휘별 반응을 분석한 결과 잔향시간이 길었던 해성고등학교와 대건고등학교는 개선 후 ‘음량’과 ‘울림’의 요소는 감소하였고 ‘경건함’과 ‘명료성’의 요소는 증가하였다. 그러나 잔향시간이 짧았던 성심여자고등학교는 개선 후 ‘명료성’ 요소는 감소하였고 ‘경건함’, ‘음량’, ‘울림’의 요소는 증가하였다. 따라서 음향성능이 개선되면 사람들이 느끼는 주관적 반응도 함께 달라지므로 향후 음향성능 평가 시 이 두 가지 평가요소를 모두 고려해야 한다.

Broadband sound attenuation by acoustic metamaterials with rigid partitions

양지은 Seoul National University 2016 국내박사

This thesis aims to develop acoustic metamaterials for broadband sound attenuation. Acoustic metamaterials, engineered composite structures whose properties cannot be found in nature, have received great attention for their exceptional performances to open new opportunities in engineering. Especially, sound attenuation capability of them has been widely investigated because of its relevance of practical applications. However, their acoustic performances are limited in a narrow bandwidth because physical mechanisms of them only work for single or selective frequencies, which poses a major obstacle in practical use. The main difficulty of designing acoustic metamaterials for the broadband performances lies on the broadening the frequency ranges of effective performance in a compact scale. To resolve this issue, this thesis presents acoustic metamaterials designed with acoustically-rigid partitions. Specifically, the proposed acoustic metamaterials are designed in a dissipative porous layer and in an acoustic layer with periodic holes to improve of sound absorption and insulation performances, respectively. The rigid partitions used in the metamaterials are arranged so as to form waveguides or resonators to control wave propagation characteristics for desired engineering purpose. Then, effective propagation distances or the effective propagation velocities of the acoustic waves propagating in the acoustic metamaterials can be tailored. It is shown that the sound attenuation performances of the proposed acoustic metamaterials are significantly enhanced in a broad range of frequency covering a low frequency range, compared with those of conventional acoustic systems without increasing a given geometric dimension. To investigate the physical mechanism of the outstanding performances of the proposed metamaterials, detailed theoretical analyzes will be carried out for each designed structure based on effective medium approach. Numerical simulations based on finite element method and experimental studies will confirm the validity of the proposed metamaterials. 본 연구는 광대역 흡차음 성능을 갖는 음향 메타물질을 설계하는 것을 목표로 한다. 음향 메타물질이란 일반적으로 존재하는 물질에서는 찾아볼 수 없는 독특한 음향학적 특성을 갖도록 설계된 물질을 말한다. 음향 메타물질에 관한 연구는 새로운 기술의 지평을 여는 새로운 학문으로, 특히 이의 소음 저감 분야에의 응용 연구가 활발히 진행되어 왔다. 그러나 현재까지 제안된 음향 메타물질은 그 성능이 매우 좁은 주파수 대역에서만 작용한다는 한계를 가지고 있다. 광대역 흡차음 성능 구현을 위한 가장 큰 장애물은 구현하고자 하는 음향 시스템의 주어진 제한된 크기 혹은 두께를 유지하면서 그 시스템이 효과적인 성능을 발휘하는 주파수 범위를 확장시키는 것이다. 해당 문제의 해결을 위해 본 연구에서는 음향학적 강체 특성을 갖는 얇은 벽으로 이루어진 구조를 사용하여 설계한 음향 메타물질을 제안한다. 본 논문에서 설계한 음향 메타물질은 구체적으로 흡음 성능을 목적으로 하는 다공성 흡음재와 차음 성능을 목적으로 하는 구멍이 있는 형태의 음향 투과층을 기반으로 한다. 제안한 음향 메타물질 설계에 사용된 강체벽은 특정한 형상으로 삽입되어 음향 도파관이나 공명기와 같은 역할을 할 수 있으며 제안한 음향 메타물질 내부에서 이 구조적 특징에 따른 독특한 파동 전파 현상을 발생시킨다. 이를 이용하여 구조물 내부 파동의 유효 전파 거리 혹은 유효 전파 속도를 조절할 수 있게 되며 이에 따른 파동 현상에 의해 제안한 메타물질의 흡차음 성능은 같은 두께 혹은 크기를 갖는 기존의 흡차음 구조에 비하여 저주파를 포함하는 넓은 주파수 대역에서 획기적으로 향상된다. 제안한 음향 메타물질에서 나타나는 물리적 현상을 효과적으로 설명하기 위해 유효 매질 모델링에 기반한 이론적 해석을 제시하며 이를 검증하기 위한 수치해석 및 실험 결과를 제시한다.

수평축 풍력발전용 터빈의 공력성능 및 소음예측에 관한 수치적 연구

모장오 한국해양대학교 2009 국내박사

Wind power is the conversion of wind energy into a useful form, such as electricity, using wind turbine. At the end of 2008, cumulative capacity of wind-powered generators all over the world was 122.2 GW. Wind power produces about 1.5% of worldwide electricity use, and is growing rapidly. As the diameter of wind turbine blade increases more and more, it becomes difficult to predict the loading and the performance of blade by unsteady aerodynamic forces, which lead to a rise of the maintenance and a unit cost of wind turbine. Also, according to the tendency to large capacity of the wind power generator, rotational speed of wind turbine blade becomes reduced and the low frequency noise becomes relatively increased so that the radiated noise can has an effect on residents of neighborhoods. This thesis focuses on the numerical investigation for the development of wind turbine blades with high performance and low noise. The study can be classified into two main categories; i.e. the predictions of the aerodynamic performance and the aero-acoustic noise using commercial code, FLUENT for the two-bladed horizontal axis wind turbine of NREL(National Renewable Energy Laboratory) Phase Ⅵ. The first category describes the flow characteristics and the aerodynamic performance for the 2D S809 airfoil and the 3D wind turbine blade, which is comprised of S809 airfoil at all spanwise locations. The computational investigation on the 2D S809 airfoil is first carried out for the purpose of applying appropriate turbulence model to the analysis of the wind turbine through the evaluation regarding to three turbulence models (k-ε, k-ω and transition SST turbulence models). The aerodynamic results of the transition SST model indicates the best agreement among the models. Also, k-ω model are in good agreement with experimental data below stall-generated angle. On the basis of the evaluation of turbulence models, the numerical study on 3D two-bladed wind turbine is performed for various wind speeds from 7m/s to 25.1m/s using k-ω turbulence model because of the computer hardware limitation in using the transition SST turbulence model. Performance results such as power coefficient, shaft torque and pressure coefficient show a good agreement with experimental data. However, root bending moment is over-predicted than the experimentally measured data by about 30% for the whole operating conditions. However, these results is in qualitative agreement with the measurement data. The second category presents the study of the aero-acoustic noise on a shroud fan for engine cooling of automobile and the two-bladed wind turbine generator of NREL Phase Ⅵ including nacelle and tower using the LES(Large Eddy Simulation) and the FW-H model. The analysis on a shroud fan is fist conducted to evaluate the possibility of applying CFD commercial code to the aero-acoustic noise. The directivity at 1st BPF shows a good agreement with experimental results which are measured in the wind tunnel. The computational investigation on aero-acoustic noise generated from wind turbine generator for various wind speeds is performed. The sound pressure level is reduced by about 3.3dB∼6.4dB with increasing distance by two times from the center of hub of the wind turbine. The sound power level is in good agreement with simple evaluation model suggested by Hagg. Also, in case of analysis of wind turbine with tip plates, the OSPL at P1 location is reduced by about 1.8dB in comparison to wind turbine without tip plates because of the effect of vortex control at blade tip. Consequently, this methodology can overall be applicable as a guideline on the optimal blade design of wind turbines with high performance and low noise in the development of wind turbine systems. 본 연구는 상용 CFD 코드를 이용하여 수평축 풍력발전용 터빈의 고성능 및 저소음 최적 블레이드 형상설계 자료로 활용되기 위한 기초자료의 확보 및 공력성능 및 소음예측 기법의 확립에 관한 연구를 수행하였으며, 다음과 같이 요약 정리 할 수 있다. 1. 풍력터빈 2차원 에어포일 S809를 대상으로 난류모델 별 수치해석적 연구를 수행하여 난류모델 별 공력성능과 유동특성의 차이점을 확인 할 수 있었으며, transition SST 모델의 경우가 모든 받음각 조건에서 우수한 성능예측 결과를 보여주었다. 또한 k-ω SST 모델의 경우도 실속각 이전의 조건에서는 비교적 우수한 성능예측 결과를 나타내었다. 2. 블레이드 설계정보를 근거로 직접 형상을 구현한 NREL Phase Ⅵ 수평축 풍력터빈 블레이드를 대상으로 3차원 유동해석 및 공력성능 평가를 수행하였으며, 블레이드 흡입면에서 발생하는 복잡한 구조의 실속현상은 이론적으로 제시된 유동구조와 서로 상당히 잘 일치하고 있음을 확인하였다. 또한 로터 블레이드에 대한 공력성능(축토크)은 NASA Ames Research Center에서 수행된 실험결과와 비교되었으며 정격풍속 7m/s에서는 0.08%의 오차 내에서 비교적 정확하게 일치하고 있음을 확인하였다. 그리고 정격풍속의 경우, 전체토크기준으로 블레이드 스팬방향 0%지점에서 40%까지는 11%, 40%지점에서 100%까지는 89%의 토크비율을 가지는 것으로 확인되었다. 따라서 로터 블레이드 설계시 스팬방향 40%까지는 구조적인 관점에서, 40%지점에서 100%까지는 공기역학적 관점에서 설계접근이 이루어져 할 것으로 판단이 된다. 3. 공력소음 해석에 대한 CFD코드의 적용가능성 평가를 목적으로 검증모델인 자동차 엔진냉각용 슈라우드 팬에 대한 공력소음 수치해석을 수행하였다. 자동차 엔진냉각용 슈라우드 팬의 경우, 팬의 전방과 후방 위치에서의 속도분포는 실험결과와 잘 일치하였으며, 팬의 반경거리 0.5m지점에서 0°, 90°방향의 1st BPF A 보정 음압레벨은 실험결과와 8.6% 오차범위 내에서 비교적 잘 일치하고 있음을 확인하였다. 또한 거리가 두배 증가함에 따라 방향별로 각기 다른 감소율을 나태내고 있음을 확인하였다. 4. NREL Phase Ⅵ 수평축 풍력발전기에 대한 소음예측과 평가를 수행하였으며, 주기적이고 안정적인 축토크값은 실험결과와 약 0.8% 오차범위 내에서 잘 일치하였다. 정격풍속에서는 블레이드 팁에서 발생하는 와류와 팁표면과의 상호작용에 의해 발생하는 이극자 소음이 지배적이며, 풍속이 증가할수록 난류의 교란과 소산에 의한 사극자 소음이 54.3% 까지 증가함을 알 수 있었다. 또한 이극자 소음원과 사극자 소음원은 각기 다른 음압 감소율로 인해 허브 중심에서 거리가 두배 증가함에 따라 총음압레벨은 원거리에서는 약 5.2dB∼6.4dB, 근거리에서는 약 3.3dB∼6.0dB까지 각기 다른 감소율을 보였다. 그리고 음향파워레벨은 Hagg가 제안한 단순평가모델 결과와 비교적 잘 일치하였으며, 거리에 따른 음압레벨은 Wagner 등이 제안한 결과와 유사한 경향을 나타내었다. 또한 정격풍속에서 팁 플레이트가 설치된 해석의 경우, 팁 플레이트가 설치되어 있지 않은 기존의 결과보다 총음압레벨은 이극자소음(블레이드)은 1.9dB 감소가, 사극자소음은 0.9dB 증가가 되어 전체적으로 1.8dB 정도 감소가 되는 효과가 있었다.

Articulatory and Acoustic Phonetics of Voice Acting

Feehan, Colette M. J ProQuest Dissertations & Theses Indiana University 2021 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Professional voice actors are an excellent, but fairly untapped population for linguistic study. These actors are linguistically naive but perform complex linguistic tasks throughout the course of their profession, and they perform these tasks safely, reliably, and consistently. While some previous studies used auditory and instrumental acoustic methods to investigate the speech produced by voice actors (Teshigawara, 2003; Teshigawara et. al., 2007; Teshigawara, 2009, cited in Teshigawara, 2011; Starr, 2015), in contrast there has been very little research on their articulation (Teshigawara & Murano, 2004). This work uses a combination of 3D/4D ultrasound, electroglottography (EGG), audio recordings, and webcam footage to observe the articulations of six voice actors (3 professionals and 3 amateurs) and compare those articulations to the acoustic outputs. Each actor read a syllable list and two stories from the Goldman Fristoe Test of Articulation 3rd ed. in both their regular adult speaking voice and a simulated child voice. Some general findings of this study indicate that actors do produce different acoustic outputs for a child voice compared to their adult voice including higher fundamental frequency (F0), different averages in acoustic measurement of vowel formants, and shorter estimates of vocal tract length. The ultrasound data indicate that actors also alter the place of lingual constriction to be more anterior, farther forward in the mouth, when imitating a child voice. EGG data, while limited to only two subjects due to the 2020 pandemic, indicate that actors may also raise their larynx to shorten the vocal tract while speaking in an imitated child voice. This work opens a new angle for linguistic study while also providing an empirical basis upon which new pedagogical methods to teach voice acting can be developed. Looking at voice actors speaking with intentionally contorted tongue positions could help us learn more about over which muscles we have volitional control within the vocal tract. This could help to improve interventions in speech therapy and even test and update acoustic-articulatory models of speech.

殘響室 音響特性에 관한 硏究

진승태 朝鮮大學校 産業大學院 1991 국내석사

The acoustic theory is considered for the conditions of divergent sound field, the measurement and estimation of diffused nature, the calculation of average inhaled sound, and the estimation of differential sound performance. In each case of the frist, second, third rever room, the reverberatory time 18.6 second (500Hz standard), 8.3 second (500Hz standard), and 12.6 second (500Hz standard) in order of measured acoustic characteristic appeard for more long than the required minimum reverberatory time 0.5 second in each rever room; thus, this shows the good rever state. In the form of rever damping curve, the diffused nature comes down more or less in domain of 125Hz, 250Hz low frequency in each rever room; but more than 500Hz shows the good diffused nature. In case of the frist, second rever room the standard deviation by the high variation and each measuring point appeard less than the standard deviation of maximum permission in all 125Hz-400Hz, and sound pressing level distribution was relatively found as uniform regardless of any position. In case of the third rever room, sound pressing distribution exceeds more or less the standard deviation of ISO in 250Hz and 1000Hz. After this, If the use of the third rever room is considered, the establishment of diffused plate, and the alteration of an inclinatory angle will not be needed. Also, the wall of each rever room, and differential sound performance is very excellent. But, because the differential sound performance of specimen opening part gate falls more or less by comparing to the wall of rever room among all rever room, the measurement over 2 kinds, at the same time, needs to be avoided Each rever room doesn't need additional acoustic treatment to more raise the diffused nature for the low-frequency substitute of 125Hz and 230Hz in each rever room needs additional adjustment of inhaled plate (a veneer board, acrylic(and, soon) having inhaled sound. If so, the careful examinatian is required. In case of the frist, second rever room the standard deviation by the high variation and each measuring point appeard less than the standard deviation of maximum permission in all 125Hz-400Hz, and sound pressing level distribution was relatively found a s uniform regardless of any position. In case of the third rever room, sound pressing distribution exceeds more or less the standard deviation of ISO in 250Hz and 1000Hz. After this, If the use of the third rever room is considered, the establishment of diffused plate, and the alteration of an inclinatory angle will not be needed. Also, the wall of each rever room, and differential sound performance is very excellent. But, because the differential sound performance of specimen opening part gate falls more or less by comparing to the wall of rever room among all rever room, the measurement over 2 kinds, at the Same time, needs to be avoided. Each rever room doesn't need additional acoustic treatment to more raise the diffused nature for the low-frequency substitute of 125Hz and 230Hz in each rever room needs additional adjustment of inhaled plate (a veneer board, acrylidand, soon) having inhaled sound. If so, the careful examinatian is required,

Understanding and Improvement of eVTOL UAV Performance through High-Fidelity Analysis of Interactional Aerodynamics

Misiorowski, Matthew P ProQuest Dissertations & Theses Rensselaer Polytec 2019 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Electric Vertical Take-Off and Landing (eVTOL) Unmanned Aerial Vehicles (UAV) are growing in popularity for both civilian and military applications. These electrically-powered rotorcraft were initially used by hobbyists but now are starting to ll roles in commercial delivery, surveillance, disaster relief, and troop resupply, amongst others. The increased use of distributed electric propulsion has given way to novel designs and the smaller scale of some of these vehicles has simplified the design. In mane cases, these aircraft use fixed-pitch rotors, eliminating the weight, drag, and complexity of a rotor swashplate (designed to provide collective and cyclic pitch control to rotors). In addition to eliminating the swashplate, the electric aircraft can use variable rotor speed amongst the multiple rotors to control the vehicle.The reduced cost and complexity of these designs has lead to research endeavors attempting to model the flight dynamics of the vehicle with low-order, computationally efficient models. The lowest of these models simply assuming rotor thrust is proportional to the revolutions per minute (RPM) of the rotor, while more complex methods use a dynamic inflow model. These reduced-order models, as well as others unmentioned, presently fail to capture the interactional flow physics that necessarily occurs between multiple rotors or rotors adjacent to nearby lifting/control surfaces. All current eVTOL UAVs have limited performance (especially in metrics like range and endurance) due to the low energy density of the lithium-polymer (Li-Po) batteries they carry, relative to hydrocarbon fuels. Additionally, when these vehicles are produced, they are typically designed with a very large margin on rotor power. This ensures the vehicle is controllable even when the model of the flight dynamics neglects any interactional aerodynamics. For the performance of these aircraft to improve, a fundamental understanding of the interactional flow physics must exist and when defined, will allow the vehicle designs to perform more efficiently in their missions.High-fidelity computational fluid dynamics (CFD) was used to solve the Navier-Stokes equations and analyze multiple rotor platforms exhibiting interactional aerodynamics. A finite element method with a sliding mesh interface as well as a finite volume scheme with overset meshes were used to fully resolve rotor motion. Convergence studies were completed to verify both schemes approached stable solutions and validation was performed against experimental data when available.Investigations of ducted rotors in hover and edgewise flight were completed on a representative eVTOL fixed-pitch rotor and duct. With baseline characteristics established, geometry modifications to the duct inlet and diffuser were analyzed. The performance of the ducted rotor system predominantly focused on the system thrust, H-force, and pitching moment. In addition, a comparison of the rotor-induced dynamic loads was made specifically focusing at the blade passage frequency. Flow visualization was used to explain performance observations by attributing specific flow features to azimuthal locations around the rotor and duct as well as explain the dynamic loads induced by the rotor.Rotor-rotor and rotor-wing interactions were investigated, applying the high-fidelity analysis to a conventional quadcopter and a quadrotor bi-play both in hover and edgewise flight. These studies analyzed the rotors and wings in isolation for comparison against the individual components in the full vehicle simulations. This comparison derives the effect of the interactional aerodynamics on performance. The study analyzed a quadcopter in different flight orientations and the quadrotor bi-plane at various angles of attack, rotor speeds, and varied the size and number of rotors on the conguration. The produced thrust and required power of each rotor were the primary performance metrics determined by these studies. Supplemental information was obtained regarding rotor pitching moment, and wing lift to drag ratios.Interactional aerodynamics were also analyzed on a stacked co-rotating system in hover. In addition to the high-delity CFD analysis, the computed aeromechanics of the rotor system were compared to a lower-order Viscous Vortex Particle Method (VVPM) with lifting line. This comparison served to illustrate the dierences that still remain between the costly high-delity analysis and more ecient models that may not capture all the important physics. In addition to the aeromechanics comparison of the methods, the acoustic properties of the rotor system were also investigated as the index angle between the stacked rotors varied.

Development of a deep learning-based prediction model for microstructural and acoustical properties of polyurethane foam

정원구 서울대학교 대학원 2025 국내석사

This study aimed to propose a deep learning-based multiscale approach for polyurethane (PU) foam, widely used as a sound-absorbing material. For the microscopic analysis of PU foam, cell size, pore size, the reciprocal of pore shape factor, and strut thickness were selected as quantified microstructural properties that significantly influence acoustical performance. The mean and standard deviation of each property were chosen as the target microstructural parameters to be predicted. Based on scanning electron microscope (SEM) images of PU foam, a UNET-based image segmentation model was developed to segment the microstructure at the pixel level into cell frame, pore, membrane, and background. The model demonstrated reasonable performance based on accuracy and F1 score, achieving 0.8393 and 0.8139, respectively. Subsequently, image post-processing techniques, such as distance transform, Voronoi-Otsu labeling, and seeded watershed algorithms, were applied to extract microstructural parameters from the segmentation results. To model the relationship between the extracted microstructural parameters and acoustical performance, deep neural network (DNN) models were developed. A total of 200 PU foam samples were utilized for training and test, with four 30x magnification SEM images obtained per sample to construct a dataset of microstructural parameters. Additionally, impedance tube measurements were conducted to acquire datasets for sound absorption coefficient and sound transmission loss as acoustical performance indicators. The test results demonstrated prediction errors within 6.7% for sound absorption coefficient and 9.7% for sound transmission loss, confirming the feasibility of reasonably linking microstructural properties to acoustical performance, even with a limited dataset. The potential of deep learning in a multiscale approach for sound-absorbing materials was demonstrated in this study. 본 연구는 흡음재로 널리 활용되는 폴리우레탄 폼을 대상으로 한 딥러닝 기반의 멀티스케일 접근법을 제시하는 것을 목표로 하였다. 폴리우레탄 폼의 미세구조 분석을 위해 음향 성능에 중요한 영향을 미치는 정량화된 미세구조 특성으로 셀 크기, 공극 크기, 공극 형상계수의 역수, 스트럿 두께를 선정하였으며 각 특성의 평균과 표준편차를 예측하고자 하는 미세구조 파라미터로 선정하였다. 폴리우레탄 폼의 주사전자현미경 이미지를 기반으로 UNET 기반의 이미지 분할 모델을 개발하여 폴리우레탄 폼의 미세구조를 구성하고 있는 셀 프레임, 공극, 멤브레인, 배경을 분할할 수 있도록 하였으며 정확도 0.8393, F1 score 0.8139 등의 합리적인 성능을 달성하였다. 이후 distance transform, vornoi-otsu labeling, seeded watershed 알고리즘 등의 이미지 후처리 기법을 적용하여 이미지 분할 결과로부터 미세구조 파라미터를 추출하는 과정을 구축하였다. 추출된 미세구조 파라미터와 음향 성능 간의 관계를 모델링하기 위해 DNN (Deep neural network) 모델을 개발하였으며, 총 200 개의 폴리우레탄 폼 샘플과 각 샘플당 4 개의 30 배율 SEM 이미지를 활용하여 미세구조 파라미터 데이터셋을 구축하였다. 또한 임피던스 튜브 측정을 통해 음향 성능 지표인 흡음률과 투과손실 데이터셋을 확보하였다. 모델 평가 결과, 흡음률과 투과손실 예측에서 각각 6.7%와 9.7% 이내의 오차를 보이며, 제한된 데이터셋에서도 미세구조 특성과 음향 성능 간의 관계를 합리적으로 예측할 수 있음을 확인하였다. 이를 통해 흡음재의 멀티스케일 접근법에서 딥러닝의 적용 가능성을 검증하였다.

Experiencing Sound in Space: A Multidisciplinary Investigation into Acoustic Space Perception

van Zyl, Marise Stanford University ProQuest Dissertations & These 2025 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Recent technical advances have enabled the creation of highly accurate simulations of a wide range of acoustic environments. Yet, despite these technological achievements, the human experience of such spaces remains poorly understood. This dissertation explores how humans perceive and interact with room acoustics, specifically reverberation, and draws on perspectives from psychology, cognitive neuroscience, and virtual reality. Across three empirical studies, this work investigates the audiovisual, neural, and behavioral dimensions of acoustic space perception. The first study demonstrates that listeners can detect mismatches between the auditory and visual characteristics of an environment, from their memory of past experiences in similar acoustic/architectural properties, with this sensitivity enhanced by musical training and spatial familiarity. These results suggest that individuals form internal representations of reverberant spaces using both auditory and visual cues. The second study uses electroencephalography (EEG) to show that reverberation and spatial sound cues are processed through distinct, yet interacting, neural pathways, with effects evident even at pre-attentive stages. The third study reveals that musicians adapt their performance strategies systematically in response to varying reverberation within virtual environments, highlighting how reverberation can affect musical behavior. These findings offer new insights into how humans perceive and make sense of reverberant spaces. Reverberation is shown to influence not only perception but also cognitive and behavioral responses, emphasizing its central role in the experience of both real and virtual environments.

Summary of Dissertation Recitals: Connecting With the Roots (+), Dominican Merengue: The Role of the Guira, Acoustic & Electro-Acoustic Works

Urena Gonzalez, Jean Carlo University of Michigan ProQuest Dissertations & Th 2023 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

These three percussion dissertation recitals were given in lieu of a written dissertation. They were presented in partial fulfillment of the requirements for Doctor of Musical Arts (Music Performance: Percussion) at the University of Michigan. The work below represents the programing and research from the dissertation recitals.The first recital, Connecting with the Roots (+), was presented on February 19, 2023 in Hankinson Rehearsal Hall at the University of Michigan. The program consisted of music written for solo Western classical percussion instruments by Dominican composers. Solos were written by Omar Ernesto Ramirez, Darwin Aquino, Dante Cucurrullo, Socrate Garcia, Aida De Moya, and Josean Jacobo. The recital also included three transcriptions and an original composition for percussion ensemble.The second recital, a lecture entitled Dominican Merengue: The Role of the Guira, was presented on March 11, 2023, in Britton Recital Hall at the University of Michigan. The lecture was representative of the research I conducted in the summer of 2019, with the support of the Center for World Performance Studies on Dominican Music. It also featured historical information and rhythmical analysis detailing the evolution of the merengue from the 1930s to 2000s. Two solos were performed to end the lecture with influences from the style of playing the guira in the main two styles of merengue: perico ripiao and merengue de orquesta.The third recital, Acoustic & Electro-Acoustic Works, was presented on March 26, 2023, in the McIntosh Theatre at the University of Michigan. The recital presented acoustic and electro-acoustic music from the 20th and 21st century. The acoustic pieces are: Boomslang by Roshanne Etezady, Asanga by Kevin Volans, and Truc a Trac by Nicolas Martynciow. The electro-acoustic works are: Deus ex metronome by Russell Wharton, Interzones by Bruce Hamilton, and Ecotones by Matthew Burtner. This program explores a wide range of the sonic aspects the percussive world has to offer, making this a varied and engaging program.

Composing Social Dynamics

Sdraulig, Charlie Basil ProQuest Dissertations & Theses Stanford Universit 2020 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The performance-installation one to one (2018-20) presents music as a dynamic, social interaction—a site to forge connections via entrainment. It is an intimately staged sequence of three pieces, each for one performer and one audience member at a time.Interpersonal entrainment describes how human beings mutually adapt to and coordinate with one another over time. These processes facilitate pro-social effects across a variety of activities, including music making.In one to one (2018-20), I contribute novel resources (i.e. conceptual frameworks, situative scoring strategies, heuristics) for creative practice, means of composing social dynamics, which nuance and expand the field of performer-audience interactions. Nonverbal communication studies offer the (quasi-)periodic cues performers attend to in each audience member. Interpersonal entrainment describes the dyadic micro-dynamics that unfold between them—reframing musical rhythm in social terms.By reciprocating each audience member’s attentional and behavioral rhythms in a sensitive, co-operative manner, the performers offer exercises in empathetic imagination.