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Measurement of Acoustic Impedance

The Journal of the Acoustical Society of America, 1948
The acoustic impedance of a sample of material forming one boundary of a shallow cylindrical cavity can be determined by measuring the sound pressure produced when a known volume current is injected into the cavity from a high impedance source. The volume current is effectively determined by observing the pressure when the cavity is terminated rigidly.
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Acoustic Impedance from Motional Impedance Diagrams

The Journal of the Acoustical Society of America, 1948
When an acoustic load is coupled to an electromagnetic transducer through a length of air column, there is a critical length at which an increment in acoustic load produces a maximum increment in electrical impedance. The method described makes use of this critical coupling to obtain an optimum precision in determining an acoustical impedance.
J. E. White, R. D. Fay
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Extraordinary acoustic transmission at low frequency by a tunable acoustic impedance metasurface based on coupled Mie resonators

, 2017
The effective impedance modulation of artificial acoustic metamaterials is crucial in application scenarios. Here, a Mie-resonator dimer is proposed as a tunable mutual inductive coupled unit to drive a mismatched to matched impedance transition, which ...
Jin Zhang, Ying Cheng, Xiao-jun Liu
semanticscholar   +1 more source

Surface acoustic impedance and causality

The Journal of the Acoustical Society of America, 2001
Several models that are commonly used to calculate the surface acoustic impedance of porous materials are examined in light of the causality requirement in its nonlocal and its approximate local forms. Strict (nonlocal) causality requires that the imaginary part of the surface acoustic impedance be the Hilbert transform of the real part.
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Asymmetric Absorption in Acoustic Metamirror Based on Surface Impedance Engineering

Physical Review Applied, 2019
Angle-dependent asymmetric acoustic absorption attracts growing interest, due to its great importance in various applications where directional responses are required, such as acoustic antennas, sensing, and angle-encoded steganography (concealed ...
Ailing Song   +6 more
semanticscholar   +1 more source

An undergraduate experiment on acoustic impedance

European Journal of Physics, 1985
An experiment is described to illustrate the concept of acoustic impedance. Pulses of sound, frequency 670 kHz, are propagated through water and through paraffin (kerosene) and the speeds of propagation are measured by the time-of-flight method. The densities of the liquids are also measured and values for the acoustic impedances are calculated.
A T Winter, P N Pope
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Acoustic metamaterials with broadband and wide-angle impedance matching

, 2018
We propose a general approach to design broadband and wide-angle impedance-matched acoustic metamaterials. Such an unusual acoustic impedance matching characteristic can be well explained by using a spatially dispersive effective medium theory.
Chenkai Liu, Jie Luo, Y. Lai
semanticscholar   +1 more source

Acoustic Impedance and Sound Absorption

The Journal of the Acoustical Society of America, 1940
Theoretical curves for acoustic impedance vs. frequency, obtained by solving the equation for wave motion within the material, are compared with recently measured values of the impedance of various sound absorbing materials. The satisfactory agreement in most cases measured indicates that that for homogeneous materials the effective values of flow ...
Richard L. Brown   +2 more
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Design of acoustic impedance analyzer [PDF]

open access: possible, 2015
Research into materials that are able to absorb low frequency sound waves has become an increasing field of study because of noise pollution in our daily lives. To combat noise pollution created by airplanes, researches have been looking into new light and thin materials to solve the problem.
openaire   +1 more source

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