acoustic impedance


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impedance

 [im-pe´dans]
1. obstruction or opposition to passage or flow, as of an electric current or other form of energy.
2. the resistance in alternating current circuits, represented by the letter Z in mathematical formulas. Medical equipment is often rated according to impedance to allow for optimum performance by matching impedance ratings. A transformer can be used between components to cause the impedances of unequal systems to match.
acoustic impedance an expression of the opposition to passage of sound waves, being the product of the density of a substance and the velocity of sound in it.

a·cous·tic im·ped·ance

the resistance that a material offers to the passage of a sound wave (colloquial); a property of a medium computed as the product of density and sound propagation speed (characteristic acoustic impedance). Discontinuities in acoustic impedance are responsible for the echoes on which ultrasound imaging is based. Unit: the rayl.

acoustic impedance

interference with the passage of sound waves by objects in the path of those waves. It equals the velocity of sound in a medium multiplied by the density of the medium. The acoustic impedance of bone may be nearly five times as great as that of blood. Testing middle ear acoustic impedance is part of audiological evaluation batteries used to detect middle ear problems.

a·cous·tic im·ped·ance

(ă-kūstik im-pēdăns)
Resistance that a material offers to the passage of a sound wave (colloquial).

impedance

obstruction or opposition to passage or flow, as of an electric current or other form of energy.

acoustic impedance
an expression of the opposition to passage of sound waves, being the product of the density of a substance and the velocity of sound in it.
References in periodicals archive ?
a1] are acoustic impedances of layers 2 and 1 respectively.
With a measurement of the downhole variations in acoustic impedance (from logging) and our measurement of the seismic wave's shape, we now have all the information we need to model the interaction of the relatively long seismic wave with the fine-scale changes in acoustic impedance.
The acoustic impedance was related by a second order polynomial with the attributes average zero crossing, slope of reflection strength, dominant frequency rating (series), average signal to noise ratio and average instantaneous phase, provided an R = 0.
The calculated acoustic impedances of polymer melt and delay line as well as those of screw root and solid PVC are listed in Table 2 for further attenuation analysis.
The sections that follow describe how the acoustic impedance can be measured and simulated.
The composite samples were suspended freely in air and their electrical impedances measured over the frequency range 300 kHz to 50 MHz where the total impedance at resonance is given by the sum of the electrical impedance and the acoustic impedances (14, 16-18).
Comparison of methods for determining specific acoustic impedance.
The backing material was constructed from a tungsten powder dispersed in an epoxy matrix, so as to match the acoustic impedance of the composite film (16, 17).
A locally reacting material is modeled by its complex acoustic impedance, which can be measured using ASTM Standard E1050 (ASTM 1998).
By analyzing signal parameters such as acoustic impedance, APTIS proprietary software was able to locate and identify plastic and ceramic weapons and simulated plastic explosives.
Moreover, the paper detailed how to measure acoustic impedance if the geometry is difficult to model and directed readers to the appropriate measurement standards.
Acoustic impedance, dominant frequency, amplitude weighted phase and instantaneous phase attributes are used as optimal attributes for the estimation of hydraulic flow units.