Computational studies of steady-state sound field and reverberant sound decay in a system of two coupled rooms

Open Physics ◽  
2007 ◽  
Vol 5 (3) ◽  
Author(s):  
Mirosław Meissner
Keyword(s):  
Steady State ◽  
Sound Pressure ◽  
Low Frequency ◽  
Sound Field ◽  
Coupled System ◽  
Reverberation Time ◽  
Acoustic Characteristics ◽  
Acoustical Properties ◽  
Forced Oscillator ◽  
Calculation Results

AbstractThe acoustical properties of an irregularly shaped room consisting of two connected rectangular subrooms were studied. An eigenmode method supported by a numerical implementation has been used to predict acoustic characteristics of the coupled system, such as the distribution of the sound pressure in steady-state and the reverberation time. In the theoretical model a low-frequency limit was considered. In this case the eigenmodes are lightly damped, thusthey were approximated by normal acoustic modes of a hard-walled room. The eigenfunctions and eigenfrequencies were computed numerically via application of a forced oscillator method with a finite difference algorithm. The influence of coupling between subrooms on acoustic parameters of the enclosure was demonstrated in numerical simulations where different distributions of absorbing materials on the walls of the subrooms and various positions of the sound source were assumed. Calculation results have shown that for large differences in the absorption coefficient in the subrooms the effect of modal localization contributes to peaks of RMS pressure in steady-state and a large increase in the reverberation time.

scholarly journals OPTIMIZATION OF REVERBERATION CHAMBER PARAMETERS FOR ACOUSTIC TESTS OF BUILDING CONSTRUCTION

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 53-58
Author(s):  
Alexandra Baldina ◽  
Lilia Pastukhova ◽  
Antonina Sekacheva
Keyword(s):  
Sound Pressure ◽  
Decay Curve ◽  
Pearson Correlation ◽  
Sound Field ◽  
Building Construction ◽  
Reverberation Time ◽  
Acoustic Characteristics ◽  
Reverberation Chamber ◽  
Four Levels ◽  
High Level

The work is devoted to the study of the acoustic characteristics of reverberation chamber. Sound pressure measurements have been carried out to study the sound field in low and high level rooms of reverberation chamber. To determine the diffuse field of sound, the sound pressure was measured at points uniformly distributed over the area of the chambers at four levels in height. The reverberation time was studied using the method of interrupted noise and fixing the decay curve by the measuring instrument. To establish the characteristic correlation between the sound pressure level at the measuring points and the distance to the sound source, the Pearson correlation coefficient was calculated. The degree of influence of the finishing room on the amount of reverberation time was investigated.

scholarly journals Investigation of damping effects on low-frequency steady-state acoustical behaviour of coupled spaces

2020 ◽  
Vol 7 (8) ◽  
pp. 200514
Author(s):  
Mirosław Meissner ◽  
Krzysztof Wiśniewski
Keyword(s):  
Steady State ◽  
Sound Pressure ◽  
Low Frequency ◽  
Sound Field ◽  
Expansion Method ◽  
Modal Expansion ◽  
Modal Expansion Method ◽  
Computational Data ◽  
The Mean ◽  
Complex Valued

In the low-frequency range, the acoustical behaviour of enclosed spaces is strongly influenced by excited acoustic modes resulting in a spatial irregularity of a steady-state sound field. In the paper, this problem has been examined theoretically and numerically for a system of coupled spaces with complex-valued conditions on boundary surfaces. Using a modal expansion method, an analytic formula for Green’s function was derived allowing to predict the interior sound field for a pure-tone excitation. To quantify the spatial irregularity of steady-state sound field, the parameter referred to as the mean spatial deviation was introduced. A numerical simulation was carried out for the system consisting of two coupled rectangular subspaces. Eigenfunctions and eigenfrequencies for this system were determined using the high-accuracy eigenvalue solver. As was evidenced by computational data, for small sound damping on absorptive walls the mean spatial deviation peaks at frequencies corresponding to eigenfrequencies of strongly localized modes. However, if the sound damping is much higher, the main cause of spatial irregularity of the interior sound field is the appearance of sharp valleys in a spatial distribution of a sound pressure level.

scholarly journals EFFICIENT ACOUSTIC COMPOSITE PANELS BASED ON GRAPHITE

2021 ◽  
Vol 6 (4) ◽  
pp. 82-90
Author(s):  
E. Fanina
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Sound Field ◽  
Fire Retardant ◽  
Pyramidal Cells ◽  
Sound Insulation ◽  
Composite Panels ◽  
Thin Membrane ◽  
Reverberation Time ◽  
Acoustic Characteristics

A set of experimental studies is carried out to determine the acoustic characteristics of three-dimensional panels of fixed thickness made of carbon-based composite material installed in the opening between the reverberation chambers. Sound insulation indices are determined when they are excited by a diffuse sound field in wide frequency ranges. The reverberation time in model chambers with different partition configurations is calculated. The optimal configuration of the partition with pyramidal cells to reduce the reverberation time in the rooms is determined. The use of graphite in the form of thin membrane applied to various surfaces can significantly reduce the sound pressure levels in the room and increase the sound insulation indices of air noise. In addition to thin membrane, graphite can be used as an additive in composite materials for sound insulation purposes. It is shown that the characteristics of such panels are quite universal. The measured acoustic characteristics of composite panels are compared with similar characteristics of traditional materials. It is determined that the composition belongs to the I group of fire-retardant efficiency and can be recommended for use as a fire-retardant material. The developed acoustic material is an effective absorbing agent that solves problems in architectural acoustics, echo cancellation in construction and architecture. Similar to metamaterials, natural and artificial graphites allow to solve these problems with small volumes and masses using simple and inexpensive technologies.

Investigation of turbulence-induced quadrupole source acoustic characteristics of a three-dimensional hydrofoil

2020 ◽  
Vol 34 (14) ◽  
pp. 2050145
Author(s):  
Rennian Li ◽  
Wenna Liang ◽  
Wei Han ◽  
Hui Quan ◽  
Rong Guo ◽  
...  
Keyword(s):  
Vortex Shedding ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Three Dimensional ◽  
Sound Field ◽  
Leading Edge ◽  
Pressure Level ◽  
Acoustic Characteristics ◽  
Eddy Simulation ◽  
Unsteady Fluid

In order to investigate the turbulence-induced acoustic characteristics of hydrofoils, the flow and sound field for a model NH-15-18-1 asymmetric hydrofoil were calculated based on the mixed method of large eddy simulation (LES) with Lighthill analogy theory. Unsteady fluid turbulent stress source around the hydrofoil were selected as the inducements of quadrupole sound. The average velocity along the mainstream direction was calculated for different Reynolds numbers [Formula: see text]. Compared to experimental measurements, good agreement was seen over a range of [Formula: see text]. The results showed that the larger the [Formula: see text], the larger the vortex intensity, the shorter the vortex initial shedding position to the leading edge of the hydrofoil, and the higher the vortex shedding frequency [Formula: see text]. The maximum sound pressure level (SPL) of the hydrofoil was located at the trailing edge and wake of the hydrofoil, which coincided with the velocity curl [Formula: see text] distribution of the flow field. The maximum SPL of the sound field was consistent with the location of the vortex shedding. There were quadratic positive correlations between the total sound pressure level (TSPL) and the maximum value of the vortex intensity [Formula: see text] and velocity curl, which verified that shedding and diffusion of vortices are the fundamental cause of the generation of the quadrupole source noise.

The Acoustic Test Report of Three Outdoor Courtyard in Shenyang Palace Museum

2014 ◽  
Vol 507 ◽  
pp. 131-137 ◽  
Author(s):  
Shen Chen ◽  
Dong Xu Zhang ◽  
Xin Xin Pan ◽  
Yang Cong
Keyword(s):  
Sound Pressure Level ◽  
Scientific Community ◽  
Sound Pressure ◽  
Sound Field ◽  
Pressure Level ◽  
Future Research ◽  
Reverberation Time ◽  
Test Report ◽  
Traditional Architecture ◽  
Solid Foundation

Scientific community is still lacking of research in sound field characteristics of the Chinese traditional architecture courtyard currently, the author chose three outdoor courtyards sound field in Shenyang Palace Museum as the research object, and firstly used the sound cutting method to do system testing of the important acoustic indicators reverberation time T10 in the Palace courtyard, then placed a dodecahedron sound player as a continuous sound source in the courtyard, test the sound pressure level on the adjacent courtyard, the purpose is to analyze the sound privacy degree of the inner courtyard of the Palace. The results may help to understand the sound field characteristics of the palace courtyard, and lay a solid foundation for the future research.

The acoustic characteristics of the “Dives in Misericordia” Church in Rome

2020 ◽  
pp. 1351010X2094865
Author(s):  
Giuseppe Ciaburro ◽  
Gino Iannace ◽  
Amelia Trematerra ◽  
Ilaria Lombardi ◽  
Maurizio Abeti
Keyword(s):  
Side Wall ◽  
Sound Field ◽  
Reverberation Time ◽  
Acoustic Measurements ◽  
Internal Length ◽  
Maximum Width ◽  
Acoustic Characteristics ◽  
Current Configuration ◽  
Double Curve ◽  
The Church

This paper discusses the acoustic characteristics of the “Dives in Misericordia” Church in Rome. The church was designed by architect Richard Meier and opened in 2003. It was made entirely of white concrete and consists of three septa with a double curve shaped like a sail. The nave roof is glass. The volume is approximately 14.000 cubic meters. The highest measuring is approximately 26 m. the width of the nave is 19.5 m, while the maximum width is 29.5 m, while the internal length is 32.0 m, while the total length is 45.6 m. It can seat approximately 240 people. The acoustic measurements were taken by placing a microphone at different points of the nave (the area occupied by the audience), with the sound source being placed on the altar. It was therefore possible to obtain a spatial distribution of the average acoustic characteristics inside the church. At a frequency of 1000 Hz, the average values of the reverberation time is about 10 s. In its current configuration, the church is neither suitable for understanding speech nor listening to music. A 3D virtual model was created and with the help of the building acoustics software it was possible to study the sound field inside the church. The possibility to carry out an appropriate acoustic correction was analyzed, in order to reduce the values of the reverberation time, by pacing on a side wall of the church an adequate number of sound-absorbing polyester panels.

Sound Field Modeling with Bottom Reflective Parameters (P,Q) Based on Parabolic Equation

2020 ◽  
Vol 28 (04) ◽  
pp. 2050029
Author(s):  
C. J. Zhang ◽  
J. R. WU ◽  
Z. D. Zhao ◽  
L. Ma ◽  
E. C. Shang
Keyword(s):  
Sound Propagation ◽  
Transmission Loss ◽  
Low Frequency ◽  
Sound Field ◽  
Propagation Models ◽  
Acoustical Properties ◽  
Sea Bottom ◽  
Model Independent ◽  
The Mean ◽  
Parameter Coupling

Acoustical properties of the sea bottom can be described using geoacoustic (GA) models. Most existing propagation models use GA parameters as the bottom properties. It is difficult to obtain GA parameters for a layered bottom because of inter parameter coupling. These problems can be solved by inverting the model-independent reflective parameters P and Q. For a multilayered bottom, a sound field computation model, RamPQ, is developed using the mapping of GA and (P, Q) spaces. The mean square error of the transmission loss in numerical simulations and experimental data for low-frequency sound propagation are employed to validate RamPQ and demonstrate the performance of the model.

Analysis of the Influence of Racks on High Speed Train Interior Noise Using Finite Element Method

2014 ◽  
Vol 675-677 ◽  
pp. 257-260 ◽  
Author(s):  
Di Wu ◽  
Jian Min Ge
Keyword(s):  
Finite Element ◽  
Sound Pressure Level ◽  
High Speed ◽  
Sound Pressure ◽  
Low Frequency ◽  
Sound Field ◽  
Pressure Level ◽  
High Speed Train ◽  
Fe Method ◽  
Proposed Model

In this paper, the finite element (FE) method was used for simulation of the low-frequency sound field in high speed train compartments. The proposed model was validated using experimental results. The FE models of the train compartments with and without racks were established respectively, and the sound pressure level of the standard point and sound field distribution in these two cases were compared. The results showed that the A-weighted sound pressure level of the standard point was 1.2 dB lower when there is no rack in the compartment.

Technical Note: Prediction of the Characteristics of Complicated Sound Fields in Long Enclosures by a Beam-Tracing Method

2002 ◽  
Vol 9 (2) ◽  
pp. 139-150 ◽  
Author(s):  
Xiangyang Zeng ◽  
Jincai Sun ◽  
Ke'an Chen
Keyword(s):  
Sound Pressure ◽  
Sound Propagation ◽  
Sound Field ◽  
Technical Note ◽  
Pressure Level ◽  
Reverberation Time ◽  
Complex Sound ◽  
Sound Fields ◽  
Sound Receiver ◽  
The Subject

The subject of this paper is the characterisation of the sound field in long enclosures. A beam-tracing computer model has been developed especially for the simulation of sound propagation throughout long enclosures. Surface diffusing reflection and air absorption are included in the model, which can predict the impulse response and acoustic indexes at arbitrary positions in the enclosure. This paper describes how the algorithm models the sound source, sound propagation and sound receiver. The algorithm was then tested in both common rooms and long enclosures by comparison of the measurement, theoretical calculation and prediction results. The characteristics of more complex sound fields in long enclosures, the prediction of reverberation time, early decay time and sound pressure level, etc, at individual points are discussed in terms of the algorithm. The results indicate that the primary characteristics of complicated sound fields in non-rectangular long enclosures are similar to those in rectangular ones.

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