scholarly journals Acoustic Absorption Coefficients at High Frequencies

1949 ◽  
Vol 21 (4) ◽  
pp. 466-466
Author(s):  
William S. Cramer
Keyword(s):  
Acoustic Absorption ◽  
Absorption Coefficients ◽  
High Frequencies

Acoustic Absorption Coefficients of the Surface of Laboratory Animals

1958 ◽  
Vol 30 (12) ◽  
pp. 1105-1111
Author(s):  
Eugene Ackerman ◽  
Robert W. Farwell ◽  
Fujio Oda ◽  
Adam Anthony
Keyword(s):  
Laboratory Animals ◽  
Acoustic Absorption ◽  
Absorption Coefficients

scholarly journals A Basic Study on a Rectangular Plane Space Sound Absorber Using Permeable Membranes

2019 ◽  
Vol 11 (7) ◽  
pp. 2185 ◽  
Author(s):  
Sakagami ◽  
Okuzono ◽  
Somatomo ◽  
Funahashi ◽  
Toyoda
Keyword(s):  
Sound Absorption ◽  
Woven Fabrics ◽  
Absorption Coefficients ◽  
Basic Study ◽  
Low Frequencies ◽  
Permeable Membrane ◽  
High Frequencies ◽  
Single Leaf ◽  
A Value ◽  
Plane Space

In this communication, the sound absorption characteristics of rectangular-shaped plane space sound absorbers without any backing structure using permeable membranes (PMs) are measured by reverberation room method. First, three types of PMs, in this study woven fabrics, are selected with different flow resistances and surface densities. They are prepared in the plane rectangular-shaped space absorbers of two different sizes. The measured results are discussed through comparison with the existing theoretical and measured results for absorbers of the other shapes or configurations. The present results and discussion demonstrate that the reverberation absorption coefficients of the proposed absorbers are low at low frequencies and converge to a moderately high value at high frequencies. Especially, ones with higher flow resistance than the air impedance converge to a value greater than 0.5, which is a theoretically estimated maximum absorption coefficient of infinite single-leaf PM. This is inferred to be attributed mainly to area effect. From these results the proposed absorbers can be used effectively despite of their very simple structure. Also it is found that the proposed absorber can offer higher sound absorption than permeable membrane absorbers of other shapes or configuration. Regarding the effect of the size, the absorbers of smaller size offer higher absorption coefficients regardless of material properties of the PMs used in the experiments.

Acoustic absorption coefficients of combustion gases

AIAA Journal ◽  
1964 ◽  
Vol 2 (2) ◽  
pp. 392-393 ◽  
Author(s):  
D. W. BLAIR ◽  
E. ERIKSEN ◽  
G. K. BERGE
Keyword(s):  
Acoustic Absorption ◽  
Absorption Coefficients ◽  
Combustion Gases

scholarly journals The Use of Fabrics to Improve the Acoustic Absorption: Influence of the Woven Fabric Thread Density Over a Nonwoven

2018 ◽  
Vol 18 (3) ◽  
pp. 269-280 ◽  
Author(s):  
Pilar Segura-Alcaraz ◽  
Jorge Segura-Alcaraz ◽  
Ignacio Montava ◽  
Marilés Bonet-Aracil
Keyword(s):  
Sound Absorption ◽  
Woven Fabric ◽  
Acoustic Absorption ◽  
Human Beings ◽  
Absorption Coefficients ◽  
Acoustic Characteristics ◽  
Resistive Layer ◽  
Acoustic Absorption Coefficient ◽  
Impedance Tube Method

Abstract Noise is frequently unnoticed, but it is one of the causes of unhealth for human beings reducing people’s quality of life. There are many materials that can be considered as acoustic absorbents. Textiles can be used to both improve the acoustic quality of and to decorate the room where they have been placed. In this study, we used some fabrics with 15, 20 and 30 ends/cm and 15, 20 and 30 picks/cm. The acoustic absorption coefficient was measured when the fabric was added as a resistive layer on top of a nonwoven made of polyester fiber. Results evidence that these fabrics can be efficiently used to modify the acoustic absorption of the nonwoven. Sound absorption coefficients measured via the impedance tube method show that these modifications occur. The results show how it is possible to improve the acoustic characteristics of a simple nonwoven to obtain sound absorption coefficients close to values of 1 at different frequencies by choosing a fabric with the appropriate combination of warp and weft count.

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