Normal incidence sound absorption measurement of individual patches in a reverberation room

2002 ◽  
Vol 112 (5) ◽  
pp. 2397-2398
Author(s):  
Paulo Massarani ◽  
Swen Muller
Keyword(s):  
Sound Absorption ◽  
Normal Incidence ◽  
Absorption Measurement

Normal‐incidence sound absorption measurement of a perforated panel using a sound‐intensity technique: Theoretical versus experimental

2000 ◽  
Vol 108 (5) ◽  
pp. 2513-2513
Author(s):  
Mohamad N. Dimon ◽  
Tharek A. Rahman ◽  
Ahmad K. Said ◽  
M. N. Ibrahim ◽  
M. Y. Jaafar
Keyword(s):  
Sound Absorption ◽  
Sound Intensity ◽  
Normal Incidence ◽  
Absorption Measurement

Tone‐Burst Technique of Sound Absorption Measurement

1970 ◽  
Vol 47 (1A) ◽  
pp. 80-80
Author(s):  
John G. Powell ◽  
John J. Van Houten
Keyword(s):  
Sound Absorption ◽  
Tone Burst ◽  
Absorption Measurement

Sound Absorption Measurement in a Circular Tube Using the Echo-Pulse Method

2010 ◽  
Vol 96 (5) ◽  
pp. 973-976 ◽  
Author(s):  
Liang Sun ◽  
Hong Hou ◽  
Li-ying Dong ◽  
Fang-rong Wan
Keyword(s):  
Sound Absorption ◽  
Circular Tube ◽  
Pulse Method ◽  
Absorption Measurement ◽  
Echo Pulse

Trial applications at gymnasiums of in-situ sound absorption measurement method by ensemble averaging technique

2021 ◽  
Vol 263 (2) ◽  
pp. 4532-4537
Author(s):  
Toru Otsuru ◽  
Reiji Tomiku ◽  
Noriko Okamoto ◽  
Siwat Lawanwadeekul
Keyword(s):  
Measurement Method ◽  
Sound Absorption ◽  
Glass Wool ◽  
Absorption Measurement ◽  
Ensemble Averaging ◽  
Averaging Technique ◽  
In Situ Conditions ◽  
Measurement Consistency ◽  
Absorption Characteristics

The authors have been published a series of papers on a measurement method for sound absorption characteristics of materials using ensemble averaging technique, i.e., EA method. The papers' results included measurement mechanisms, measurement uncertainty, and so on. Herein, to examine adaptability, especially in in-situ conditions, the EA method is applied to measure absorption characteristics of materials installed in two gymnasiums. A glass-wool panel with the dimension of 0.5 m by 0.5 m by 0.05 m and with the density of 32 kg m^-3 was brought around and measured to check the measurement consistency. Several measurements were conducted during badminton plays were undergoing. Measured sound absorption coefficients revealed that most results agree well with those measured in reverberation rooms. Certain improvement is necessary for the specimen brought to the in-situ measurement to keep the consistency. The inconsistency is considered to originate from unstable conditions between the specimen and floor.

A Tone‐Burst Technique of Sound‐Absorption Measurement

1970 ◽  
Vol 48 (6A) ◽  
pp. 1299-1303 ◽  
Author(s):  
John G. Powell ◽  
John J. Van Houten
Keyword(s):  
Sound Absorption ◽  
Tone Burst ◽  
Absorption Measurement

scholarly journals DESAIN OF ACOUSTIC SANDWICH COMPOSITE FROM FOAM CONCRETE AND PALM FIBER

2018 ◽  
Vol 18 (2) ◽  
pp. 72-76
Author(s):  
Devya Kartika Devya ◽  
Mursal Mursal ◽  
Zulkarnain Djalil
Keyword(s):  
White Noise ◽  
Sound Absorption ◽  
Bottom Layer ◽  
Absorption Measurement ◽  
Sample Thickness ◽  
Sandwich Composite ◽  
Foam Concrete ◽  
Low Frequencies ◽  
Palm Fiber ◽  
Layer Composition

The purpose of this research were to investigate the influence of palm fiber composition and the number of hole cavities was varied with design Acoustic Sandwich Composite on sound absorption of acoustic panel. Acoustic panel were made of palm fiber as core and foam concreate as skin upper layer and bottom layer where there is a hole cavity on skin upper layer. Composition and the number of hole cavities was varied from 1 to 3 kg and the number of hole cavities from 25 to 81 hole. Sound absorption measurement was conducted by using reverberation room method based on ISO-354 (2003) with pink and white noise as sound source.The results showed that sample thickness affect acoustic absorption value effectively shifted at low frequencies, as in this research the best sound absorption occurs in panel with composition palm fiber most widely 3 kg, but coeffesient absorpsi value effective is in the range 250 Hz and use the number of hole cavities at skin upper layer of each sample effectively cause sound absorption coeffisient value increased, for both pink and white noise from sound source.Keyword : acoustic panel, foam concrete, palm fiber, sandwich composite, and absorption coefficient

scholarly journals Excess sound absorption at normal incidence by two microperforated panel absorbers with different impedance

2011 ◽  
Vol 32 (5) ◽  
pp. 194-200 ◽  
Author(s):  
Motoki Yairi ◽  
Kimihiro Sakagami ◽  
Kenichi Takebayashi ◽  
Masayuki Morimoto
Keyword(s):  
Sound Absorption ◽  
Normal Incidence

scholarly journals Simulation of Normal Incidence Sound Absorption Coefficients of Perforated Panels With/Without Glass Wool by Transmission Line Parameters in a Two-Port Network

2016 ◽  
Vol 44 ◽  
pp. 123-130
Author(s):  
Takayoshi Nakai
Keyword(s):  
Transmission Line ◽  
Input Impedance ◽  
Thermal Conduction ◽  
Sound Absorption ◽  
Sound Propagation ◽  
Viscous Friction ◽  
Normal Incidence ◽  
Glass Wool ◽  
Absorption Coefficients ◽  
Transfer Function Method

This paper describes simulation of normal incidence sound absorption coefficients of perforated panels by transmission line parameters in a two-port network. Maa and Sakagami have investigated micro perforated panels, MPP. But their theories can treat only near 1 % perforation rates of perforated panels with back cavities. If sound propagates as a plane wave, sound propagation can be represented as transmission line parameters in a two-port network. Perforated panels, back cavities, and glass wool absorption materials are represented as matrix of transmission line parameters, respectively. Transmission line parameters of a perforated panel with a back cavity are calculated as multiplication of their matrices. An input impedance can be calculated from the transmission line parameters. A normal incident absorption coefficient is calculated from the input impedance. Holes of the perforated panels have losses of viscous friction and thermal conduction at their walls. Simulations are done in the condition of 0.25 mm to 5 mm diameters of holes, 0.25 % to 25 % perforation rates, 0.5 mm to 5 mm thickness of the perforated panels with back cavities in which there are or are not glass wool absorption materials. The results of these simulations are good agreements with the results of our measurements by transfer function method except in the condition of more than 1 mm diameter of holes.

Investigation of a Compound Perforated Panel Absorber With Backing Cavities Partially Filled With Polymer Materials

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
C. Q. Wang ◽  
Y. S. Choy
Keyword(s):  
Sound Absorption ◽  
Normal Incidence ◽  
Polyester Fiber ◽  
Polymer Materials ◽  
Element Simulation ◽  
Parallel Arrangement ◽  
Cavity Configuration ◽  
Absorption Performance ◽  
Good Agreement ◽  
Panel Absorber

The paper concerns the sound absorption performance of a compound absorber which consists of a parallel arrangement of multiple perforated panel absorbers of different backing cavity depths partially filled with poroelastic polymer materials. Three polymer materials are considered: expandable polystyrene (EPS) foam, polymethacrylimide (PMI) foam, and polyester fiber. The normal incidence sound absorption coefficients of the compound panel absorber are tested experimentally. Results show that the former two foams can achieve similar absorption performance to the rigid cavity configuration, while the resonances shift to lower frequencies due to the changes of effective cavity depths. It is also found that the additional attenuation by polymer foams may improve sound absorption, but the effect is marginal. For polyester fiber, results show that it performs more like a single perforated panel absorber. Finite element simulation of the compound panel absorber is also discussed, and good agreement is observed between simulated and experimental results.

Sound Absorption Measurements and Numerical Estimation of Non Acoustical Parameters of some Moroccan Raw Green Materials

2014 ◽  
Vol 1051 ◽  
pp. 95-101
Author(s):  
Garoum Mohammed ◽  
Chaimaa Benayad
Keyword(s):  
Sound Absorption ◽  
Normal Incidence ◽  
Optimization Techniques ◽  
Acoustical Parameters ◽  
Acoustical Properties ◽  
Thermal Insulating ◽  
Green Materials ◽  
Direct Measurements ◽  
Inverse Estimation ◽  
Absorption Measurements

Knowledge of acoustical properties of granular and fibrous sustainable materials has been stimulated thanks to their rather easy handling and durability. In this work direct measurements of the normal incidence sound absorption coefficient of three non consolidated materials (esparto fibers, cork and perlite) have been carried out using the so-called transfer function method. These materials are plentiful in Morocco and they require low amounts of energy for processing, which makes them attractive as either thermal insulating or sound absorbing materials. Results show that the acoustical efficiency of studied materials is comparable to traditional materials. In addition, an inverse estimation of non acoustical parameters (flow resistivity, tortuosity and porosity) of these materials has been performed introducing a new predictability approach. This is based on Global Sensitivity Analysis combined with Global Numerical Optimization Techniques, regarding most usual mathematical models.

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