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

COMPARISON OF NORMAL INCIDENT SOUND ABSORPTION COEFFICIENT OF DIRECT PIERCING CARVED WOOD PANEL FOR CIRCULAR, GEOMETRY AND FLORAL DESIGN

2016 ◽  
Vol 78 (6-10) ◽  
Author(s):  
Mohd Zamri Jusoh ◽  
Nazli Che Din ◽  
Mohamad Ngasri Dimon
Keyword(s):  
Boundary Element Method ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Intensity ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Wood Panel ◽  
High Frequencies ◽  
Wood Carving ◽  
Circular Design

Direct Piercing Carved Wood Panel (DPCWP) is among the famous Malay wood carving art in the Malay culture. It is the best example of Malay people’s creativity and masterpiece. In this paper, the comparison of normal incidence sound absorption coefficient,  (SAC) for three major types of design for the DPCWP is discussed. The simplest form of DPCWP, the circular type, then the geometry and floral types were investigated based on simulation and measurement works using sound intensity method to determine the normal incidence SAC, for 30% and 40% perforation ratios. The simulation work was carried out by using BEASY Acoustic software based on Boundary Element Method (BEM). From the results, there is an identical trend for DPCWP with geometry and floral design from 250 Hz to 4 kHz. At high frequencies (1 kHz to 4 kHz), both design show the tendency of decrement, suggesting that the complexity of the design does affect the average SAC value. However, for circular design, SAC is higher than other design at 1 kHz and shows a similar trend with other design at 2 kHz and 4 kHz for both simulation and measurement result.

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.

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