scholarly journals The Determination of Reverberant Sound Absorption Coefficients from Acoustic Impedance Measurements

1950 ◽  
Vol 22 (1) ◽  
pp. 80-80
Author(s):  
Albert London
Keyword(s):  
Acoustic Impedance ◽  
Sound Absorption ◽  
Absorption Coefficients ◽  
Impedance Measurements

Experimental study of wood acoustic absorption characteristics

Holzforschung ◽  
2014 ◽  
Vol 68 (4) ◽  
pp. 467-476 ◽  
Author(s):  
Jerzy Smardzewski ◽  
Wojciech Batko ◽  
Tadeusz Kamisiński ◽  
Artur Flach ◽  
Artur Pilch ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Acoustic Properties ◽  
Acoustic Absorption ◽  
Laboratory Measurements ◽  
Absorption Coefficients ◽  
Tropical Zone ◽  
Fiber Dimensions ◽  
Air Flow Resistivity ◽  
Oak Ash

Abstract The objective of this study was to determine normal impedance on the surface as well as sound absorption coefficients for several wood species from Europe and from the tropical zone. The mathematical models of Miki, Attenborough, and Allard – dealing with acoustic properties of porous materials – have also been compared. The air flow resistivity exhibits a distinct link between fiber dimensions and wood porosity. The highest sound absorption coefficient was found for oak, ash, sapeli, and pine woods at 2 kHz frequency. The Attenborough model provides results closest to laboratory measurements, although it still requires significant improvements. The Miki and Allard models have some drawbacks and should be applied with reservation for the determination of wood acoustic properties.

Impedance Measurements at the Eardrum as an Aid to Diagnosis

1963 ◽  
Vol 6 (4) ◽  
pp. 315-327 ◽  
Author(s):  
Alan S. Feldman
Keyword(s):  
Middle Ear ◽  
Acoustic Impedance ◽  
Rapid Determination ◽  
Clinical Investigation ◽  
Acoustic Method ◽  
Clinical Measurement ◽  
Impedance Measurements ◽  
The Status ◽  
Conductive Hearing

The clinical measurement of acoustic impedance at the eardrum is described. Significant modifications of the traditional Schuster bridge by Zwislocki led to the development of an acoustic impedance bridge that permits a sufficiently reliable and rapid determination of absolute acoustic impedance. The results of clinical investigation with this instrument demonstrate the value of the acoustic method in the evaluation of the status of the middle ear mechanism. The presence of conductive hearing losses due to various middle ear conditions may be detected and differentiated by objective and quantitative impedance measurements.

scholarly journals Diffuse Sound Absorptive Properties of Parallel-Arranged Perforated Plates with Extended Tubes and Porous Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1091 ◽  
Author(s):  
Dengke Li ◽  
Daoqing Chang ◽  
Bilong Liu
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Porous Materials ◽  
Sound Absorption ◽  
Azimuthal Angle ◽  
Octave Band ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Perforated Plates ◽  
Absorption Performance

The diffuse sound absorption was investigated theoretically and experimentally for a periodically arranged sound absorber composed of perforated plates with extended tubes (PPETs) and porous materials. The calculation formulae related to the boundary condition are derived for the periodic absorbers, and then the equations are solved numerically. The influences of the incidence and azimuthal angle, and the period of absorber arrangement are investigated on the sound absorption. The sound-absorption coefficients are tested in a standard reverberation room for a periodic absorber composed of units of three parallel-arranged PPETs and porous material. The measured 1/3-octave band sound-absorption coefficients agree well with the theoretical prediction. Both theoretical and measured results suggest that the periodic PPET absorbers have good sound-absorption performance in the low- to mid-frequency range in diffuse field.

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