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 ?
The tool's display reports the sample's acoustic impedance at that location.
Detection of non-wet scaffold parts can be performed the most objectively and precisely because of the meaningful difference between the acoustic impedance of the polymer media and air bubbles.
S] can be calculated as the ratio between the acoustic impedance [z.
adiabatic compressibility(Pad), intermolecular free length(Lf), relaxation time (X)), free volume (Vf), internal pressure (R), acoustic impedance (Z), surface tension(S), attenuation(a/f2), Rao's constant(R), molar volume (Vm), cohesive energy(CE) showed that there are presence of specific molecular interactions in ethanol and ethyl/methyl-4-(aryl)-6-methyl-2 oxo/thioxo-1,2,3,4-tetrahydropyridimi-dine-5-carboxylate molecules, which are responsible to increase absorption and transmission.
d] are the upstream and downstream acoustic impedance (ratio of sound pressure to volume velocity) respectively.
These studies have demonstrated that input acoustic impedance measurements (which provide valuable information on the wind instrument under evaluation) made by using acoustic reflectometry are quite close to theory and easily applied; likewise, having some restrictions in the information obtained at high frequencies and in the size of the reflectometer, which is of considerable length [1].
When the acoustic impedance between the plates was increased by using a cement mixture, an increase in the fragmentation was achieved.
The acoustic impedance is determined by the density p and of the acoustic velocity v of the material (2):
The Nanofibers also increase the acoustic impedance of absorption materials for acoustic applications.
Based on acoustic impedance characteristics, these sands are interpreted to have preserved porosity.
de Sherbrooke, Canada) have retained chapters on topics including plane waves in isotropic fluids and solids, acoustic impedance at normal incidence of fluids, acoustic impedance at oblique incidence in fluids, the Biot theory of sound propagation in porous materials having an elastic frame, and modeling multilayered systems with porous materials using the transfer matrix method.