Noise reduction of plenum window with add-in dual staggered sound scatterer arrays

2021 ◽  
Vol 263 (5) ◽  
pp. 1539-1547
Author(s):  
Xiaolong LI ◽  
Shiu Keung Tang ◽  
Shiu-Keung, Tang
Keyword(s):  
Noise Reduction ◽  
Transmission Loss ◽  
Computational Simulation ◽  
Sound Transmission ◽  
Sound Field ◽  
Model Space ◽  
Sound Transmission Loss ◽  
Sound Energy ◽  
Window System ◽  
Sonic Crystal

In present study, a 1:4 scaled down model was used to explore the noise reduction across the plenum window with add-in dual staggered scatterer arrays (sonic-crystal). Reverberation time inside the model space was measured firstly to eliminate the effect of the possible reverberation variation on the sound transmission loss of the plenum window. Two sonic-crystal arrays, the two-by-two and two-by-three scatterer arrangements, were adopted for measurement. A total of four arrays was thus tested after the staggering. Computational simulation was conducted for the sound field inside the plenum chamber to study the noise reduction mechanism of the present window system. Results show that the noise reduction of the plenum window was improved by varying degrees due to the placement of the dual staggered sonic-crystal. The Installation of the dual staggered sonic-crystal increased the sound energy reflections out of the plenum window inlet and decreased the sound energy that passed through the plenum window cavity. At the same time, the resonances inside the window cavity also contributed to the sound transmission loss of the plenum window. The noise reduction across the plenum window was enhanced. The improvement was between ~2 to ~2.7 dBA.

Observations on the Systematic Deviations between Two Methods of Measuring Sound Transmission Loss

1996 ◽  
Vol 3 (1) ◽  
pp. 1-11 ◽  
Author(s):  
F. Jacobsen ◽  
H. Ding
Keyword(s):  
Measurement Errors ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Field ◽  
Sound Intensity ◽  
Field Method ◽  
Sound Transmission Loss ◽  
Careful Measurement ◽  
Linear Decay ◽  
Comparable Size

The paper examines and discusses possible explanations of the systematic deviations between conventional and intensity-based sound transmission loss measurements frequently reported in the literature. Both the conventional diffuse-field method and the method based on the sound intensity technique are subject to several systematic errors of comparable size. The sources of error include non-linear decay functions, the absorption of the partition itself, and intensity measurement errors, which are aggravated by the fact that the sound field conditions are usually fairly difficult. It is concluded that with very careful measurement procedures there are no systematic deviations.

The Significance of the Incident Sound Field on the Sound Transmission Loss of a Finite Panel

2005 ◽  
Vol 12 (4) ◽  
pp. 225-235 ◽  
Author(s):  
Jeremy W. Trevathan ◽  
John R. Pearse
Keyword(s):  
Plane Wave ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Field ◽  
Normal Incidence ◽  
Angle Of Incidence ◽  
Sound Transmission Loss ◽  
Wave Source ◽  
Integration Limit ◽  
Definition Of

Results are presented for the numerically predicted sound transmission loss of a finite panel excited by plane wave sources at various angles of incidence. It is shown that the limitation commonly imposed upon the integration of the ‘mass law’ is not arbitrary. Rather, it is the upper integration limit at which a function dependent on cos2 (the ‘mass law’), when integrated, becomes equal to a function dependent on cos (the method used in this study, the ISO 140 experimental method) which has been integrated from zero to 90 degrees. The current definition of sound transmission loss implicitly assumes that a plane wave sound source at normal incidence to the panel surface will produce the highest level of excitation in the panel, and as the angle of incidence is increased the panel will experience decreasing levels of excitation. However, it is shown here that the excitation experienced by a panel due to a plane wave source is almost independent of the angle of incidence.

Angular distribution of incident sound energy for estimating the sound transmission loss of multilayered panels

1998 ◽  
Vol 103 (5) ◽  
pp. 2814-2814
Author(s):  
Hyun‐Ju Kang ◽  
Hyun‐Sil Kim ◽  
Jae‐Seung Kim ◽  
Sang‐Ryul Kim ◽  
Jeong‐Guon Ih
Keyword(s):  
Angular Distribution ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Transmission Loss ◽  
Sound Energy

Control of sound transmission into a hybrid double-wall sandwich cylindrical shell

2021 ◽  
pp. 107754632098213
Author(s):  
Seyyed M Hasheminejad ◽  
Ali Jamalpoor
Keyword(s):  
Cylindrical Shell ◽  
Shell Structure ◽  
Transmission Loss ◽  
Sliding Mode ◽  
Circular Cylindrical Shell ◽  
Sound Transmission ◽  
Sound Field ◽  
Air Gap ◽  
Sound Transmission Loss ◽  
Double Wall

A 3D analytical model is formulated for diffuse sound field transmission control through a smart hybrid double concentric sandwich circular cylindrical shell structure in presence of external and internal air gap mean flows. The multi-input multi-output sliding mode control is applied to enhance the sound transmission loss characteristics via direct control action of a uniform force piezoelectric actuator layer along with semi-active variation of the stiffness/damping characteristics of the electrorheological fluid core layer incorporated in a non-collocated configuration within the external or internal shell structure. Extensive numerical simulations examine the uncontrolled/controlled diffuse field sound transmission loss spectrums in a broad frequency range for single-wall and hybrid double-wall sandwich shells at selected external and air gap Mach numbers. The proposed smart hybrid active/semi-active double-wall configuration is demonstrated to provide satisfactory overall acoustic insulation control performance with much lower operative energy requirements. Limiting cases are considered, and validity of the formulation is verified against the available data.

scholarly journals Analysis of the transmission loss of double-leaf panels with an equivalent spring–mass model for studs

2020 ◽  
Vol 37 ◽  
pp. 126-133
Author(s):  
Yuan-Wei Li ◽  
Chao-Nan Wang
Keyword(s):  
Distribution Curve ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Experimental Results ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Mass Model ◽  
Steel Stud ◽  
Panel Thickness ◽  
Stiffness Distribution

Abstract The purpose of this study was to investigate the sound insulation of double-leaf panels. In practice, double-leaf panels require a stud between two surface panels. To simplify the analysis, a stud was modeled as a spring and mass. Studies have indicated that the stiffness of the equivalent spring is not a constant and varies with the frequency of sound. Therefore, a frequency-dependent stiffness curve was used to model the effect of the stud to analyze the sound insulation of a double-leaf panel. First, the sound transmission loss of a panel reported by Halliwell was used to fit the results of this study to determine the stiffness of the distribution curve. With this stiffness distribution of steel stud, some previous proposed panels are also analyzed and are compared to the experimental results in the literature. The agreement is good. Finally, the effects of parameters, such as the thickness and density of the panel, thickness of the stud and spacing of the stud, on the sound insulation of double-leaf panels were analyzed.

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