An improved two-microphone transfer function method for measuring oblique absorption coefficient in the free field using numerical modeling

2015 ◽  
Vol 137 (4) ◽  
pp. 2401-2401
Author(s):  
Hubert S. Hall ◽  
Joseph F. Vignola ◽  
John A. Judge ◽  
Diego Turo ◽  
Teresa J. Ryan
Keyword(s):  
Numerical Modeling ◽  
Transfer Function ◽  
Absorption Coefficient ◽  
Function Method ◽  
Free Field ◽  
Transfer Function Method

scholarly journals Comparison of Static Wave Ratio and transfer Function Method in Determining the Sound Absorption Coefficient of Materials

2018 ◽  
Vol 5 (2) ◽  
pp. 1-11
Author(s):  
mohammad oliaei ◽  
Rostam Golmohammadi ◽  
Mohsen Aliabadi ◽  
Reza Shahidi ◽  
Mostafa Orvati movafagh ◽  
...  
Keyword(s):  
Transfer Function ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Function Method ◽  
Sound Absorption Coefficient ◽  
Transfer Function Method

Development of an Indigenous Impedance Tube

2015 ◽  
Vol 786 ◽  
pp. 149-155
Author(s):  
Wei Hong Tan ◽  
Rosmaini Ahmad ◽  
Nur Hafizah Zunaidi ◽  
Ruslizam Daud ◽  
E.M. Cheng
Keyword(s):  
Transfer Function ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Function Method ◽  
Theoretical Background ◽  
Sound Absorption Coefficient ◽  
Frequency Range ◽  
Cavity Depth ◽  
Impedance Tube ◽  
Transfer Function Method

Fabrication of an impedance tube for measuring sound absorption coefficient is presented in this paper. Transfer-function method is chosen for the sound absorption analysis. The impedance tube is designed and fabricated in accordance with ISO 10534-2. The tube is made from brass with diameter of 114.3 mm and length of 1.42 m. It is designed for the frequency range 60 Hz to 1800Hz. Three microphone positions are installed to achieve the frequency range with a single tube. The theoretical background of transfer-function method between two microphones is discussed. Initially, impedance tube is characterized by the measurement without testing material in the tube. Micro-perforated panel (MPP) with 50 mm and 100 mm of cavity depth are used for measurement. The sound absorption coefficient measurement of the MPP is compared with theory and good agreement is achieved. Various problems related to design and construction is addressed and the optimal configuration is presented.

Influence of Spheroid and Fiber-Like Waste-Tire Rubbers on the Sound Absorption Coefficient of Rubberized Mortars

2019 ◽  
Vol 958 ◽  
pp. 63-68
Author(s):  
Edson Jansen Pedrosa Miranda Jr. ◽  
Andressa Fernanda Angelin ◽  
S.F. Rodrigues ◽  
Luísa Andréia Gachet-Barbosa ◽  
J.M.C. dos Santos
Keyword(s):  
Transfer Function ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Function Method ◽  
Sound Absorption Coefficient ◽  
Experimental Characterization ◽  
Acoustic Performance ◽  
Waste Tire ◽  
Transfer Function Method ◽  
Rubber Particles

We study the sound absorption coefficient of rubberized mortars in response to the incorporation of 7.5%, 15% and 30% of waste-tire rubbers in place of sand at a water-to-cement mass (w/c) ratio of 0.48. We consider two different morphologies of rubber particles, namely spheroid (S) and fiber-like (F) particles. Experimental characterization was performed after 7 days of curing. The mixtures were performed by density, water absorption, void index and sound absorption. We choose the transfer function method with one microphone successively in two locations in order to obtain the sound absorption coefficient using an impedance tube. Sound absorption coefficient results indicate a slightly enhancement for 7.5% S, 15% S, 30% S and 7.5% F mixtures from 1600 Hz to 2000 Hz. The best acoustic performance is observed for 30% S and 7.5% F mixtures from 850 Hz to 2000 Hz.

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