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Experimental and computational validation of a scaled train tunnel model using modal analysis

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Frontiers of Mechanical Engineering 2013年第4期8卷 420-428页

作者： Janice B.D'SOUZA Sangarapillai KANAPATHIPILLAI School of Mechanical and Manufacturing Engineering The University of New South Wales

Acoustic engineers are faced with the challenge of minimising reverberation time in their designs so as to contribute to the health and well-being of those traveling by train and those on the *** the problem is easy to identify,it is not as simple to *** acoustical environment of a train tunnel is complex,with a variety of noise contributing factors such as train announcements,speech of commuters,ventilation systems,electrical equipment and wheel and rail *** a result,there is some difficulty in modeling the complete acoustic environment with computational or acoustic first *** this study,an experimental rig was constructed to model the acoustic behavior within a *** modal properties for the 300 Hz to 1500 Hz range,including resonances and mode shapes were identified and were shown to successfully correspond to theoretical results and a computational model created in COMSOL using Finite Element Analysis.

关键词： reverberation time acoustic environment modal properties resonances

Acoustic improvement on two lecture auditoria： Simulation and experiment

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Frontiers of Architectural Research 2017年第1期6卷 1-16页

作者： Soha Eldakdoky Ahmed Elkhateeb Department of Architecture Faculty of Engineering Helwan University Egypt Department of Architecture Faculty of Engineering Ain Shams University Egypt

Based on the commonly used indicators for speech intelligibility, this work acoustically evaluates the two largest auditoria in the Faculty of Engineering, Helwan University, Cairo, Egypt, using experimental and digital simulation techniques. Design treatments were also suggested to improve the acoustic performance of the auditoria, where the impact of these treatments was checked using the simutation as well. The models that were analysed using the CATT-software were first validated utilizing the results of the fietd work in the unoccupied rooms. The results showed that the acoustic quality of the two auditoria are far from the optimal conditions due to their improper acoustic characteristics and the high noise revers as weft. The results of improvement proposals showed that altering the ceiling shape and adding efficient absorptive materials to the rear surfaces successfully reduced the excessive reverberation time to the optimal values, increased the earty reflections and eliminated the shadow zones. In addition, decreasing the noise Levels by 20 dB due to improving the window insulation noticeably improved the speech intelligibitity at all receivers.

关键词： Acoustic performance Speech intelligibility reverberation time Background noise lever Lecture auditoria

Research on the coefficient of sound absorption in turbid water

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Journal of Marine Science and Application 2008年第2期7卷 135-138页

作者：刘永伟李琪 College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150001China

China’s coastal waters are turbid and the properties of the seabed are complex. This negatively impacts the performance of underwater detection equipment. The properties of sound absorption in turbid water are not well understood. In this paper, the coefficient of sound absorption in turbid water was measured by the reverberation technique. All work was done in a reverberation barrel made of seamless aluminum. First, pure water was poured into the reverberation barrel and its reverberation time measured. Next, various concentrations of turbid water were poured into the barrel and their reverberation time measured. After all data had been gathered, the coefficient of sound absorption in turbid water of different concentrations was calculated. From this we determined a law of sound absorption in turbid water as summarized in the paper.

关键词： reverberation time sound absorption turbid water

USE OF CORK SHEETS FOR ROOM ACOUSTIC CORRECTION

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Journal of Green Building 2020年第2期15卷 45-55页

作者： Gino Iannace Giuseppe Ciaburro Luigi Guerriero Amelia Trematerra Department of Architecture and Industrial Design Università della Campania“Luigi Vanvitelli”Borgo San Lorenzo 81031Aversa(Ce)—Italy

Cork is a sustainable material and at the end of its useful life it can be disposed of into the environment without causing *** paper analyzes an acoustic correction system made of cork sheets mounted at an opportune distance from the walls inside a *** cork sheets have a thickness equal to 1.5 *** sound absorption coefficients of the cork sheets were initially evaluated by mounting samples inside an impedance tube,then creating a back cavity at a suitable distance from a rigid *** distances considered were:3,5,10 and 15 cm.A room used as an office with a volume of about 90 m^(3)and plastered walls was considered as a *** this type of environment,suitable acoustic comfort conditions are *** acoustic characteristics were analyzed through a virtual model with an architectural acoustics software in an empty room and then with the introduction of sound-absorbing cork *** of the acoustic characteristics of the empty room were taken and subsequently with the walls lined with cork panels mounted at a distance of 3.0 cm from the rigid rear wall.A configuration was analyzed,in line with what was carried out in the numerical model,covering a surface of 5m^(2)of the *** results of the numerical simulations as well as the experimental measurements are discussed.

关键词： cork absorption coefficient acoustic reverberation time measurements acoustic simulation

Evaluation of the Acoustic Environment in a Protestant Church Based on Measurements of Acoustic Descriptors

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Journal of Building Construction and Planning Research 2016年第3期4卷 172-189页

作者： Samuel Ansay Paulo Henrique Trombetta Zannin Laboratory of Environmental and Industrial Acoustics and Acoustic Comfort Federal University of Paraná Curitiba Brazil

The new guidelines of the Catholic Church are in line with the guidelines adopted by Protestant churches since the Reformation, unifying appreciation for the liturgical practices of preaching and congregational singing. These guidelines require that the room, in this case the church, provides appropriate acoustic characteristics, which can be characterized by acoustic descriptors such as reverberation time (RT), Clarity (C80) and Definition (D50). In this article, we analyzed the acoustic quality of a protestant church whose design tried to follow these guidelines. Our findings revealed the poor quality of the acoustic environment in terms of both speech intelligibility and music. These findings emphasized the need to adopt not only reverberation time but also other acoustic descriptors such as Clarity and Definition in church design.

关键词： Acoustic Quality Church Clarity Definition reverberation time

Research on the reverberation absorption coeeficient of material measured by underwater reverberation field method

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Research on the reverberation absorption coeeficient of mate...