A Tone‐Burst Technique of Sound‐Absorption Measurement

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.

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Method of Testing of Sound Absorption Properties of Materials Intended for Ultrasonic Noise Protection

Archives of Acoustics ◽

10.2478/aoa-2013-0022 ◽

2013 ◽

Vol 38 (2) ◽

pp. 191-195 ◽

Cited By ~ 1

Author(s):

Dariusz Pleban

Keyword(s):

Sound Absorption ◽

Free Field ◽

Tone Burst ◽

Mineral Wool ◽

Frequency Range ◽

Absorption Properties ◽

Open Cell Foam ◽

Properties Of Materials ◽

Cell Foam

Abstract Efficient ultrasonic noise reduction by using enclosures requires the knowledge of absorbing properties of materials in the frequency range above 4 kHz. However, standardized methods enable determination of absorption coefficients of materials in the frequency range up to 4 kHz. For this reason, it is proposed to carry out measurements of the sound absorption properties of materials in the free field by means of a tone-burst technique in the frequency range from 4 kHz to 40 kHz at angles of incidence varying from 0° to 60°. The absorption coefficient of a material is calculated from the reflection coefficient obtained by reflecting a tone-burst from both a perfectly reflecting panel and a combination of this panel and the sample of the tested material. The tests results show that mineral wool and polyurethane open-cell foam possess very good absorbing properties in this frequency range.

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DESAIN OF ACOUSTIC SANDWICH COMPOSITE FROM FOAM CONCRETE AND PALM FIBER

Jurnal Natural ◽

10.24815/jn.v18i2.9706 ◽

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

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