Transformation acoustics(TA)has emerged as a powerful tool for designing several intriguing conceptual devices,which can manipulate acoustic waves in a flexible manner,yet their applications are limited in Hermitian m...Transformation acoustics(TA)has emerged as a powerful tool for designing several intriguing conceptual devices,which can manipulate acoustic waves in a flexible manner,yet their applications are limited in Hermitian materials.In this work,we propose the theory of complex-coordinate transformation acoustics(CCTA)and verify the effectiveness in realizing acoustic non-Hermitian metamaterials.Especially,we apply this theory for the first time to the design of acoustic parity-time(PT)and antisymmetric parity-time(APT)metamaterials and demonstrate two distinctive examples.First,we use this method to obtain the exceptional points(EPs)of the PT/APT system and observe the spontaneous phase transition of the scattering matrix in the transformation parameter space.Second,by selecting the Jacobian matrix's constitutive parameters,the PT/APT-symmetric system can also be configured to approach the zero and pole of the scattering matrix,behaving as an acoustic coherent perfect absorber and equivalent laser.We envision our proposed CCTAbased paradigm to open the way for exploring the non-Hermitian physics and finding application in the design of acoustic functional devices such as absorbers and amplifiers whose material parameters are hard to realize by using the conventional transformation method.展开更多
In automotive industries,panel acoustic contribution analysis(PACA)is used to investigate the contributions of the body panels to the acoustic pressure at a certain point of interest.Currently,PACA is implementedmostl...In automotive industries,panel acoustic contribution analysis(PACA)is used to investigate the contributions of the body panels to the acoustic pressure at a certain point of interest.Currently,PACA is implementedmostly by either experiment-based methods or traditional numerical methods.However,these schemes are effort-consuming and inefficient in solving engineering problems,thereby restraining the further development of PACA in automotive acoustics.In this work,we propose a PACA scheme using discontinuous isogeometric boundary element method(IGABEM)to build an easily implementable and efficient method to identify the relative acoustic contributions of each automotive body panel.Discontinuous IGABEMis more accurate and converges faster than continuous BEM and IGABEM in the interior sound pressure evaluation of automotive compartments.In this work,a contribution ratio is defined to estimate the relative acoustic contribution of the structure panels;it can be calculated by reusing the coefficient matrix that has already been generated in the sound pressure evaluation process.The utilization of the parallel technique enables the proposed method to be more efficient than conventional methods;it is validated in two numerical examples,including a car passenger compartment subjected to realistic boundary conditions.A sound pressure response experiment based on a steel box is conducted to verify the accuracy of the interior sound pressure calculation using discontinuous IGABEM.This work is expected to promote the practical process of IGABEM for application in automotive acoustic problems.展开更多
This paper proposes amodified formulation of the singular boundarymethod(SBM)by introducing the combined Helmholtz integral equation formulation(CHIEF)and the self-regularization technique to exterior acoustics.In the...This paper proposes amodified formulation of the singular boundarymethod(SBM)by introducing the combined Helmholtz integral equation formulation(CHIEF)and the self-regularization technique to exterior acoustics.In the SBM,the concept of the origin intensity factor(OIF)is introduced to avoid the singularities of the fundamental solutions.The SBM belongs to the meshless boundary collocation methods.The additional use of the CHIEF scheme and the self-regularization technique in the SBM guarantees the unique solution of the exterior acoustics accurately and efficiently.Consequently,by using the SBM coupled with the CHIEF scheme and the self-regularization technique,the accuracy of the numerical solution can be improved,especially near the corresponding internal characteristic frequencies.Several numerical examples of two-dimensional and threedimensional benchmark examples about exterior acoustics are used to verify the effectiveness and accuracy of the proposed method.The proposed numerical results are compared with the analytical solutions and the solutions obtained by the other numerical methods.展开更多
The fluid mechanics of water entry is studied through investigating the underwater acoustics and the supercavitation.Underwater acoustic signals in water entry are extensively measured at about 30 different positions ...The fluid mechanics of water entry is studied through investigating the underwater acoustics and the supercavitation.Underwater acoustic signals in water entry are extensively measured at about 30 different positions by using a PVDF needle hydrophone.From the measurements we obtain (1)the primary shock wave caused by the impact of the blunt body on free surface;(2)the vapor pressure inside the cavity;(3)the secondary shock wave caused by pulling away of the cavity from free surface;and so on.The supercavitation induced by the blunt body is observed by using a digital high-speed video camera as well as the single shot photography.The periodic and 3 dimensional motion of the supercavitation is revealed.The experiment is carried out at room temperature.展开更多
Acoustic rhinometry could numerically describe up- per airway condition of air draft by drawing a graph plotting the distance from the nostril vs. the cross-sectional area. Some decreases on the graph correspond to th...Acoustic rhinometry could numerically describe up- per airway condition of air draft by drawing a graph plotting the distance from the nostril vs. the cross-sectional area. Some decreases on the graph correspond to the typical anatomic structures of human nasal cavity. The 3-dimensional, computing fluid dynamic model of the same person was developed based on computed tomography scans. The veracity of the CFD model was valued by contrasting the relevant areas of stenosis site between the model and the AR graph. The aim in this study is to make clear how to use an AR to help improve and enrich the CFD model with the information of graph acquired from the measurement. The combination of AR and CT can be used to establish a living human nasal cavity model with higher significant information content.展开更多
Based on transformation acoustic methodology, we propose an algorithm for designing acoustic non-resonant lens antenna, which is competent to generate multiple directive beams that are pointing at the desired directio...Based on transformation acoustic methodology, we propose an algorithm for designing acoustic non-resonant lens antenna, which is competent to generate multiple directive beams that are pointing at the desired direction.Unattainable with previous works, the present approach is capable of adjusting the directivity of each radiated beam individually, which is of the utmost importance in several acoustic applications such as in sonar systems. A linear transformation function is intentionally used for eliminating the inhomogeneity of the obtained materials and to pave the way towards more general acoustic patterns. Several numerical simulations are performed to show the capability of the proposed method in manipulating the acoustic waves. To authenticate the concept,a structure that can generate four beams with different directivities is realized with non-resonant meta-fluid bi-layered structure through effective medium theory.展开更多
Environmental Acoustics is a professional course that educates students majoring in Acoustics.Affected by practical equipment and other factors,the teaching effect of knowledge points relevant to subjective auditory p...Environmental Acoustics is a professional course that educates students majoring in Acoustics.Affected by practical equipment and other factors,the teaching effect of knowledge points relevant to subjective auditory perception contained in the course is poor.Taking the course of Spatial Hearing and 3D Stereo as an example,this study develops a virtual simulation experiment system for the topic of subjective hearing perception in order to carry out the reform and practice of immersive teaching.Combined with the virtual simulation experiment project with high sense of presence,students are supported by the actual auditory perception effect in the whole learning process and have achieved good learning effect.展开更多
Approved by the State Planning Commission in 1989, the National Laboratory of Acoustics (NLA) was officially set up at the Chinese Academy of Sciences (CAS) in 1990. Since then, NLA has been open to the scientists fro...Approved by the State Planning Commission in 1989, the National Laboratory of Acoustics (NLA) was officially set up at the Chinese Academy of Sciences (CAS) in 1990. Since then, NLA has been open to the scientists from home and abroad. The director of NLA is Prof. Zhang Renbe, a CAS member and member of the International Commission on Acoustics (ICA). The chairman of the NLA Academic Committee is Prof. Hou Ziqiang.展开更多
The traditional performing arts and theatrical buildings in China can be traced back to a long history and were well developed during Song and Yuan Dynasties, 11th-14th centuries. Pavilion stage, opened on three sides...The traditional performing arts and theatrical buildings in China can be traced back to a long history and were well developed during Song and Yuan Dynasties, 11th-14th centuries. Pavilion stage, opened on three sides and thrusting into the audience area, was unique and the most popular form in the open-air theatres, the courtyard theatres, and the indoor theatres up to the present day. As the traditional Chinese opera is performed in an abstract way, no stage settings are required and used. Therefore, the pavilion stage including the flat or domed ceiling and the back wall is virtually functioned as a reflective shell, which increases the early reflections and also intensifies the sound in the audience area. Meanwhile, it provides sufficient self-support to the performers. Acoustical parameters including reverberation time RT, early decay time EDT, acoustic ratio C (50), strength index (loudness) G, and stage support factor ST1 were measured and reported on several traditional theatrical buildings.展开更多
Acomprehensive experiment on shallow water acoustics with the inseparable combination of the acoustical and oceanographic means, which is uncommon internationally, was conducted successfully in the Far Yellow Sea by a...Acomprehensive experiment on shallow water acoustics with the inseparable combination of the acoustical and oceanographic means, which is uncommon internationally, was conducted successfully in the Far Yellow Sea by a group of Chinese and U.S. scientists from August 21 to September 1,1996. The basic task of ocean acoustic research is to study the interaction between sound wave and ocean media, which includes exploring the laws of influence due to spatial and temporal variability of the ocean environment, such as ocean surface waves,inhomogeneity of sea water and sea bottom struc-展开更多
Generation of magnetic micrbubbles and their basic magnetic and acoustic mechanism are reviewed. The ultrasound (US) and magnetic resonance (MR) dual imaging, the controlled therapeutic delivery, as well as theran...Generation of magnetic micrbubbles and their basic magnetic and acoustic mechanism are reviewed. The ultrasound (US) and magnetic resonance (MR) dual imaging, the controlled therapeutic delivery, as well as theranostic multifunctions are all introduced based on recent research results. Some on-going research is also discussed.展开更多
The objective of receptivity is to investigate the mechanisms by which external disturbances generate unsta- ble waves. In hypersonic boundary layers, a new receptivity process is revealed, which is that fast and slow...The objective of receptivity is to investigate the mechanisms by which external disturbances generate unsta- ble waves. In hypersonic boundary layers, a new receptivity process is revealed, which is that fast and slow acoustics through nonlinear interaction can excite the second mode near the lower-branch of the second mode. They can generate a sum-frequency disturbance though nonlinear interaction, which can excite the second mode. This receptivity process is generated by the nonlinear interaction and the nonparal- lel nature of the boundary layer. The receptivity coefficient is sensitive to the wavenumber difference between the sumfrequency disturbance and the lower-branch second mode. When the wavenumber difference is zero, the receptivity coefficient is maximum. The receptivity coefficient decreases with the increase of the wavenumber difference. It is also found that the evolution of the sum-frequency disturbance grows linearly in the beginning. It indicates that the forced term generated by the sum-frequency disturbance resonates with the second mode.展开更多
In this paper we present the Projection Based Interpolation (PBI) technique for construction of continuous approximation of MRI scan data of the human head. We utilize the result of the PBI algorithm to perform three ...In this paper we present the Projection Based Interpolation (PBI) technique for construction of continuous approximation of MRI scan data of the human head. We utilize the result of the PBI algorithm to perform three dimensional (3D) Finite Element Method (FEM) simulations of the acoustics of the human head. The computational problem is a multi-physics problem modeled as acoustics coupled with linear elasticity. The computational grid contains tetrahedral finite elements with the number of equations and polynomial orders of approximation varying locally on finite element edges, faces, and interiors. We utilize our own out-of-core parallel direct solver for the solution of this multi-physics problem. The solver minimizes the memory usage by dumping out all local systems from all nodes of the entire elimination tree during the elimination phase.展开更多
Comfort in buildings is one of the most requested value to reach. Today, designers have to deal with so many technical features including outer appearance, air-conditioning, structural layouts, acoustic insulation and...Comfort in buildings is one of the most requested value to reach. Today, designers have to deal with so many technical features including outer appearance, air-conditioning, structural layouts, acoustic insulation and inner treatments, materials bio-compatibility, material recycling and reuse, water wasting and so on. In the same time, costumers want to buy buildings which won’t cost a lot in terms of heating and cooling as in the past. Besides, every single apartment, loft, office etc., even if there are many of them in a single building, has to be very quiet. Voluntary or compulsory standards, protocols and state laws lead the designers throughout the project and in some cases to the final in field tests too. Nevertheless, different sort of calculations, leading philosophy, expected results, parameters and tags are included in order to achieve the final aims. In this paper, energy efficiency and acoustic performances of buildings are discussed, proposing and comparing designing solutions for a specific case study.展开更多
Room acoustics play an important role in the intelligibility of speech. The main aspect of acoustics that is usually studied is the duration of the reverberation decay, since a long decay causes a blurring of phonemes...Room acoustics play an important role in the intelligibility of speech. The main aspect of acoustics that is usually studied is the duration of the reverberation decay, since a long decay causes a blurring of phonemes. However, other parameters of the acoustics such as the strength of the reverberation can actually improve intelligibility. These factors do not receive the same attention. In many common practical situations such as classrooms and residential rooms, it would be of value to quantitatively study the acoustics to optimize the room’s function, but this is not done routinely due to the expected expense or difficulty involved. This research explores inexpensive first-principle methods to quantitatively measure three key parameters of a room’s acoustics: the reverberation decay time RT60, the reverberant intensity IR, and the room’s total absorption A. The required equipment includes two laptops installed with certain free softwares. Generation of the required noise signal and level detection are carried out using the REW software, and long-duration recordings are carried out using the Audacity software. The procedures are simple enough to be performed without specialized training and do not require specialized equipment, only commonly available household resources. This research also sheds light on the fact that not all reverberation is bad and that strong but short-duration reverberation can enhance communication. This information can be expected to benefit schools and other venues where speech intelligibility is vital.展开更多
CRC Press,Talor&Francis Group,ISBN:978-1-4822-6043-4(Hardback),2017,6th Ed.This book represents a classical text in room acoustics-its original edition having been first pubfished in 1973.The author was a chair pr...CRC Press,Talor&Francis Group,ISBN:978-1-4822-6043-4(Hardback),2017,6th Ed.This book represents a classical text in room acoustics-its original edition having been first pubfished in 1973.The author was a chair professor at the Institute of Technical Acoustics,the Technical University in Aachenl Germany since 1972 until his retirement in 1995.The author of the book intends to introduce展开更多
1 Introduction The science of sound in ducts can be traced back to the time when the sound wave equation was first derived.Many important ideas,concepts,and methods for acoustics were first developed for sound fields ...1 Introduction The science of sound in ducts can be traced back to the time when the sound wave equation was first derived.Many important ideas,concepts,and methods for acoustics were first developed for sound fields in ducts.Anyone with a little training in acoustics must be aware of normal specific acoustical impedance,the standing wave ratio,transmission line theory,and the cut-on frequencies of high-order wave-guide modes.In fact,duct acoustics has been so extensively taught展开更多
基金the National Key Research and Development Program of China(Grant No.2022YFA1404402)the National Natural Science Foundation of China(Grant Nos.12174190,11634006,12074286,and 81127901)+1 种基金the High-Performance Computing Center of Collaborative Innovation Center of Advanced Microstructuresthe the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Transformation acoustics(TA)has emerged as a powerful tool for designing several intriguing conceptual devices,which can manipulate acoustic waves in a flexible manner,yet their applications are limited in Hermitian materials.In this work,we propose the theory of complex-coordinate transformation acoustics(CCTA)and verify the effectiveness in realizing acoustic non-Hermitian metamaterials.Especially,we apply this theory for the first time to the design of acoustic parity-time(PT)and antisymmetric parity-time(APT)metamaterials and demonstrate two distinctive examples.First,we use this method to obtain the exceptional points(EPs)of the PT/APT system and observe the spontaneous phase transition of the scattering matrix in the transformation parameter space.Second,by selecting the Jacobian matrix's constitutive parameters,the PT/APT-symmetric system can also be configured to approach the zero and pole of the scattering matrix,behaving as an acoustic coherent perfect absorber and equivalent laser.We envision our proposed CCTAbased paradigm to open the way for exploring the non-Hermitian physics and finding application in the design of acoustic functional devices such as absorbers and amplifiers whose material parameters are hard to realize by using the conventional transformation method.
基金funded by the National Natural Science Foundation of China (Grant No.52175111)。
文摘In automotive industries,panel acoustic contribution analysis(PACA)is used to investigate the contributions of the body panels to the acoustic pressure at a certain point of interest.Currently,PACA is implementedmostly by either experiment-based methods or traditional numerical methods.However,these schemes are effort-consuming and inefficient in solving engineering problems,thereby restraining the further development of PACA in automotive acoustics.In this work,we propose a PACA scheme using discontinuous isogeometric boundary element method(IGABEM)to build an easily implementable and efficient method to identify the relative acoustic contributions of each automotive body panel.Discontinuous IGABEMis more accurate and converges faster than continuous BEM and IGABEM in the interior sound pressure evaluation of automotive compartments.In this work,a contribution ratio is defined to estimate the relative acoustic contribution of the structure panels;it can be calculated by reusing the coefficient matrix that has already been generated in the sound pressure evaluation process.The utilization of the parallel technique enables the proposed method to be more efficient than conventional methods;it is validated in two numerical examples,including a car passenger compartment subjected to realistic boundary conditions.A sound pressure response experiment based on a steel box is conducted to verify the accuracy of the interior sound pressure calculation using discontinuous IGABEM.This work is expected to promote the practical process of IGABEM for application in automotive acoustic problems.
基金supported by the National Science Fund of China(Grant No.12122205)the Six Talent Peaks Project in Jiangsu Province of China(Grant No.2019-KTHY-009).
文摘This paper proposes amodified formulation of the singular boundarymethod(SBM)by introducing the combined Helmholtz integral equation formulation(CHIEF)and the self-regularization technique to exterior acoustics.In the SBM,the concept of the origin intensity factor(OIF)is introduced to avoid the singularities of the fundamental solutions.The SBM belongs to the meshless boundary collocation methods.The additional use of the CHIEF scheme and the self-regularization technique in the SBM guarantees the unique solution of the exterior acoustics accurately and efficiently.Consequently,by using the SBM coupled with the CHIEF scheme and the self-regularization technique,the accuracy of the numerical solution can be improved,especially near the corresponding internal characteristic frequencies.Several numerical examples of two-dimensional and threedimensional benchmark examples about exterior acoustics are used to verify the effectiveness and accuracy of the proposed method.The proposed numerical results are compared with the analytical solutions and the solutions obtained by the other numerical methods.
基金The project supported by the "BaiRen Plan" of Chinese Academy of Sciences
文摘The fluid mechanics of water entry is studied through investigating the underwater acoustics and the supercavitation.Underwater acoustic signals in water entry are extensively measured at about 30 different positions by using a PVDF needle hydrophone.From the measurements we obtain (1)the primary shock wave caused by the impact of the blunt body on free surface;(2)the vapor pressure inside the cavity;(3)the secondary shock wave caused by pulling away of the cavity from free surface;and so on.The supercavitation induced by the blunt body is observed by using a digital high-speed video camera as well as the single shot photography.The periodic and 3 dimensional motion of the supercavitation is revealed.The experiment is carried out at room temperature.
文摘Acoustic rhinometry could numerically describe up- per airway condition of air draft by drawing a graph plotting the distance from the nostril vs. the cross-sectional area. Some decreases on the graph correspond to the typical anatomic structures of human nasal cavity. The 3-dimensional, computing fluid dynamic model of the same person was developed based on computed tomography scans. The veracity of the CFD model was valued by contrasting the relevant areas of stenosis site between the model and the AR graph. The aim in this study is to make clear how to use an AR to help improve and enrich the CFD model with the information of graph acquired from the measurement. The combination of AR and CT can be used to establish a living human nasal cavity model with higher significant information content.
文摘Based on transformation acoustic methodology, we propose an algorithm for designing acoustic non-resonant lens antenna, which is competent to generate multiple directive beams that are pointing at the desired direction.Unattainable with previous works, the present approach is capable of adjusting the directivity of each radiated beam individually, which is of the utmost importance in several acoustic applications such as in sonar systems. A linear transformation function is intentionally used for eliminating the inhomogeneity of the obtained materials and to pave the way towards more general acoustic patterns. Several numerical simulations are performed to show the capability of the proposed method in manipulating the acoustic waves. To authenticate the concept,a structure that can generate four beams with different directivities is realized with non-resonant meta-fluid bi-layered structure through effective medium theory.
基金This research was supported by the Key Teaching Reform Project of Northwestern Polytechnical University-Practical Teaching Reform of Environmental Acoustics Course Group Supported by Virtual Auditory Perception Experiment Project(Project Number:2021JGZ04).
文摘Environmental Acoustics is a professional course that educates students majoring in Acoustics.Affected by practical equipment and other factors,the teaching effect of knowledge points relevant to subjective auditory perception contained in the course is poor.Taking the course of Spatial Hearing and 3D Stereo as an example,this study develops a virtual simulation experiment system for the topic of subjective hearing perception in order to carry out the reform and practice of immersive teaching.Combined with the virtual simulation experiment project with high sense of presence,students are supported by the actual auditory perception effect in the whole learning process and have achieved good learning effect.
文摘Approved by the State Planning Commission in 1989, the National Laboratory of Acoustics (NLA) was officially set up at the Chinese Academy of Sciences (CAS) in 1990. Since then, NLA has been open to the scientists from home and abroad. The director of NLA is Prof. Zhang Renbe, a CAS member and member of the International Commission on Acoustics (ICA). The chairman of the NLA Academic Committee is Prof. Hou Ziqiang.
基金supported by the grant from National Science Foundation,Beijing(Project No.50078038).
文摘The traditional performing arts and theatrical buildings in China can be traced back to a long history and were well developed during Song and Yuan Dynasties, 11th-14th centuries. Pavilion stage, opened on three sides and thrusting into the audience area, was unique and the most popular form in the open-air theatres, the courtyard theatres, and the indoor theatres up to the present day. As the traditional Chinese opera is performed in an abstract way, no stage settings are required and used. Therefore, the pavilion stage including the flat or domed ceiling and the back wall is virtually functioned as a reflective shell, which increases the early reflections and also intensifies the sound in the audience area. Meanwhile, it provides sufficient self-support to the performers. Acoustical parameters including reverberation time RT, early decay time EDT, acoustic ratio C (50), strength index (loudness) G, and stage support factor ST1 were measured and reported on several traditional theatrical buildings.
文摘Acomprehensive experiment on shallow water acoustics with the inseparable combination of the acoustical and oceanographic means, which is uncommon internationally, was conducted successfully in the Far Yellow Sea by a group of Chinese and U.S. scientists from August 21 to September 1,1996. The basic task of ocean acoustic research is to study the interaction between sound wave and ocean media, which includes exploring the laws of influence due to spatial and temporal variability of the ocean environment, such as ocean surface waves,inhomogeneity of sea water and sea bottom struc-
基金Project supported by the National Basic Research Program of China (Grant Nos.2011CB933503 and 2013CB733804)the National Natural Science Foundation of China (Grant No.31000453)the Fundamental Research Funds for Central Universities (Grant No.2013CB733804)
文摘Generation of magnetic micrbubbles and their basic magnetic and acoustic mechanism are reviewed. The ultrasound (US) and magnetic resonance (MR) dual imaging, the controlled therapeutic delivery, as well as theranostic multifunctions are all introduced based on recent research results. Some on-going research is also discussed.
基金supported by the National Natural Science Foundation of China (Grants 11332007 and 11202147)the Specialized Research Fund for the Doctoral Program of Higher Education (Grants 20120032120007)
文摘The objective of receptivity is to investigate the mechanisms by which external disturbances generate unsta- ble waves. In hypersonic boundary layers, a new receptivity process is revealed, which is that fast and slow acoustics through nonlinear interaction can excite the second mode near the lower-branch of the second mode. They can generate a sum-frequency disturbance though nonlinear interaction, which can excite the second mode. This receptivity process is generated by the nonlinear interaction and the nonparal- lel nature of the boundary layer. The receptivity coefficient is sensitive to the wavenumber difference between the sumfrequency disturbance and the lower-branch second mode. When the wavenumber difference is zero, the receptivity coefficient is maximum. The receptivity coefficient decreases with the increase of the wavenumber difference. It is also found that the evolution of the sum-frequency disturbance grows linearly in the beginning. It indicates that the forced term generated by the sum-frequency disturbance resonates with the second mode.
文摘In this paper we present the Projection Based Interpolation (PBI) technique for construction of continuous approximation of MRI scan data of the human head. We utilize the result of the PBI algorithm to perform three dimensional (3D) Finite Element Method (FEM) simulations of the acoustics of the human head. The computational problem is a multi-physics problem modeled as acoustics coupled with linear elasticity. The computational grid contains tetrahedral finite elements with the number of equations and polynomial orders of approximation varying locally on finite element edges, faces, and interiors. We utilize our own out-of-core parallel direct solver for the solution of this multi-physics problem. The solver minimizes the memory usage by dumping out all local systems from all nodes of the entire elimination tree during the elimination phase.
文摘Comfort in buildings is one of the most requested value to reach. Today, designers have to deal with so many technical features including outer appearance, air-conditioning, structural layouts, acoustic insulation and inner treatments, materials bio-compatibility, material recycling and reuse, water wasting and so on. In the same time, costumers want to buy buildings which won’t cost a lot in terms of heating and cooling as in the past. Besides, every single apartment, loft, office etc., even if there are many of them in a single building, has to be very quiet. Voluntary or compulsory standards, protocols and state laws lead the designers throughout the project and in some cases to the final in field tests too. Nevertheless, different sort of calculations, leading philosophy, expected results, parameters and tags are included in order to achieve the final aims. In this paper, energy efficiency and acoustic performances of buildings are discussed, proposing and comparing designing solutions for a specific case study.
文摘Room acoustics play an important role in the intelligibility of speech. The main aspect of acoustics that is usually studied is the duration of the reverberation decay, since a long decay causes a blurring of phonemes. However, other parameters of the acoustics such as the strength of the reverberation can actually improve intelligibility. These factors do not receive the same attention. In many common practical situations such as classrooms and residential rooms, it would be of value to quantitatively study the acoustics to optimize the room’s function, but this is not done routinely due to the expected expense or difficulty involved. This research explores inexpensive first-principle methods to quantitatively measure three key parameters of a room’s acoustics: the reverberation decay time RT60, the reverberant intensity IR, and the room’s total absorption A. The required equipment includes two laptops installed with certain free softwares. Generation of the required noise signal and level detection are carried out using the REW software, and long-duration recordings are carried out using the Audacity software. The procedures are simple enough to be performed without specialized training and do not require specialized equipment, only commonly available household resources. This research also sheds light on the fact that not all reverberation is bad and that strong but short-duration reverberation can enhance communication. This information can be expected to benefit schools and other venues where speech intelligibility is vital.
文摘CRC Press,Talor&Francis Group,ISBN:978-1-4822-6043-4(Hardback),2017,6th Ed.This book represents a classical text in room acoustics-its original edition having been first pubfished in 1973.The author was a chair professor at the Institute of Technical Acoustics,the Technical University in Aachenl Germany since 1972 until his retirement in 1995.The author of the book intends to introduce
文摘1 Introduction The science of sound in ducts can be traced back to the time when the sound wave equation was first derived.Many important ideas,concepts,and methods for acoustics were first developed for sound fields in ducts.Anyone with a little training in acoustics must be aware of normal specific acoustical impedance,the standing wave ratio,transmission line theory,and the cut-on frequencies of high-order wave-guide modes.In fact,duct acoustics has been so extensively taught