Improved Sound Field Reverberance and Diffusivity in a Reverberation Chamber Through Implementation of Resonant-Diffusing Wall Panels

2015 ◽  
Vol 101 (1) ◽  
pp. 181-189 ◽  
Author(s):  
David T. Bradley ◽  
Candido Diaz ◽  
Erik Snow
Keyword(s):  
Sound Field ◽  
Reverberation Chamber ◽  
Wall Panels

Design and Construction of a Small Reverberation Chamber Applied to Absorption and Scattering Acoustic Measurements

2014 ◽  
Vol 1077 ◽  
pp. 197-202
Author(s):  
D. Hernandez ◽  
E.J. Liu ◽  
J.H. Huang ◽  
Y.C. Liu
Keyword(s):  
High Frequency ◽  
Integration Method ◽  
Sound Field ◽  
Acoustic Measurements ◽  
Acoustic Characteristics ◽  
Reverberation Chamber ◽  
Scattering Coefficients ◽  
Reverberation Chambers ◽  
The Cost ◽  
Design And Construction

Reverberation chambers are used to create a diffuse incidence sound field, where multiple types of acoustic measurements can be performed. The chambers tend to have a large volume in order to extent the reverberation time. However, this requirement may be conditioned by the cost and the infrastructure limitations. This paper presents the design and construction of a small-scaled reverberation chamber of 3 m3 for middle-high frequency acoustic measurements. On the design, the acoustic characteristics of chamber are confirmed via finite element computer simulation. As case studies, absorption and scattering coefficients of several materials and diffusors are measured. The reverberation times needed for the measurements were obtained by the impulse response integration method. The small reverberation chamber demonstrated to be a reliable tool for middle and high frequency acoustic measurements.

Absorption Characteristics of Suspended Absorbers

1994 ◽  
Vol 1 (4) ◽  
pp. 279-286
Author(s):  
L. Kortchmar ◽  
M. A. Nabuco De Araujo ◽  
S.N.Y. Gerges
Keyword(s):  
Sound Absorption ◽  
Sound Field ◽  
Reverberation Chamber ◽  
High Frequencies ◽  
Statistical Precision ◽  
Air Space ◽  
Absorption Characteristics

The question of the arrangement of sound absorbers has been under study for some time. In our approach we conducted a sequence of experiments in a reverberation chamber to determine the optimal sound absorption for different configurations of suspended absorbers using various air spaces and a central dividing panel between them. The results obtained were compared with measurements of the panels, tested against a solid backing as specified in ISO-R-354. It is shown that a porous absorber is more efficient at high frequencies if it is suspended in the sound field rather than against a solid backing. It was also found that the efficiency of an air space between the two porous sheets that compose a suspended absorber is moderately increased when a central divider is used. The statistical precision of the test was also investigated.

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 Low frequency sound field reconstruction in a non-rectangular room using a small number of microphones

Acta Acustica ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 5 ◽  
Author(s):  
Thach Pham Vu ◽  
Hervé Lissek
Keyword(s):  
Low Frequency ◽  
Sound Field ◽  
Acoustic Properties ◽  
Room Acoustics ◽  
Low Frequencies ◽  
Reverberation Chamber ◽  
Sound Fields ◽  
Accurate Knowledge ◽  
Sound Field Reconstruction ◽  
Rectangular Room

An accurate knowledge of the sound field distribution inside a room is required to identify and optimally locate corrective measures for room acoustics. However, the spatial recovery of the sound field would result in an impractically high number of microphones in the room. Fortunately, at low frequencies, the possibility to rely on a sparse description of sound fields can help reduce the total number of measurement points without affecting the accuracy of the reconstruction. In this paper, the use of Greedy algorithm and Global curve-fitting techniques are proposed, in order to first recover the modal parameters of the room, and then to reconstruct the entire enclosed sound field at low frequencies, using a reasonably low set of measurements. First, numerical investigations are conducted on a non-rectangular room configuration, with different acoustic properties, in order to analyze various aspects of the reconstruction frameworks such as accuracy and robustness. The model is then validated with an experimental study in an actual reverberation chamber. The study yields promising results in which the enclosed sound field can be faithfully reconstructed using a practically feasible number of microphones, even in complex-shaped and damped rooms.

scholarly journals An Energy Model for the Calculation of Room Acoustic Parameters in Rectangular Rooms with Absorbent Ceilings

2021 ◽  
Vol 11 (14) ◽  
pp. 6607
Author(s):  
Erling Nilsson ◽  
Emma Arvidsson
Keyword(s):  
Model Comparison ◽  
Field Model ◽  
Energy Analysis ◽  
Sound Field ◽  
Acoustical Parameters ◽  
Acoustic Parameters ◽  
Reverberation Chamber ◽  
Additional Information ◽  
Classroom Configuration ◽  
Speech Clarity

The most common acoustical treatment of public rooms, such as schools, offices, and healthcare premises, is a suspended absorbent ceiling. The non-uniform distribution of the absorbent material, as well as the influence of sound-scattering objects such as furniture or other interior equipment, has to be taken into account when calculating room acoustic parameters. This requires additional information than what is already inherent in the statistical absorption coefficients and equivalent absorption areas provided by the reverberation chamber method ISO 354. Furthermore, the classical diffuse field assumption cannot be expected to be valid in these types of rooms. The non-isotropic sound field has to be considered. In this paper, a statistical energy analysis (SEA) model is derived. The sound field is subdivided into a grazing and non-grazing part where the grazing part refers to waves propagating almost parallel to the suspended ceiling. For estimation of all the inherent parameters in the model, the surface impedance of the suspended ceiling has to be known. A method for estimating the scattering and absorbing effects of furniture and objects is suggested in this paper. The room acoustical parameters reverberation time , speech clarity , and sound strength were calculated with the model and compared with calculations according to the classical diffuse field model. Comparison with measurements were performed for a classroom configuration. With regard to all cases, the new model agrees better with measurements than the classical one.

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