in exploration seismology, estimation of elastic parameters of rocks using seismic amplitudes is considered as inverse problems. nowadays, model-based and more generally optimization-based algorithms are of the most common methods of seismic inversion. these algorithms which are known as deterministic methods, are suffering from two main problems; first, vertical resolution of outputs is very l...

Variations in the acoustic impedance throughout cells and tissue can be used to gain insight into cellular microstructures and the physiologic state of the cell. Ultrasound imaging can be used to create a map of the acoustic impedance, on which fluctuations can be used to help identify the dominant ultrasound scattering source in cells, providing information for ultrasound tissue characterizati...

refractor ambiguities are big problem in seismic refraction method especially in seismic engineering. there can be hidden subsurface geological phenomena such as hidden faults and shear zones which are not simply predicted by the travel-time graph or some geophysical methods. head wave amplitudes are used to show the resolution of refractor ambiguities and the existence of anisotropy in complex...

In (3) φ is an arbitrary test function and ρ the density of the fluid. In consequence, to calculate the acoustic field and thus, to solve the acoustic wave equation, the impedance Za on the surface Γ has to be known. Hence, a measurement technique to determine the acoustic impedance is of great importance, because a realistic sound field can only be calculated, if the real acoustic impedance at...

The acoustic impedance at the diaphragm of an electroacoustic transducer can be varied using a range of basic electrical control strategies, amongst which are electrical shunt circuits. These passive shunt techniques are compared to active acoustic feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. The formulation of feedback-based acoustic impedance co...

The acoustic behaviour of wind instruments is largely determined by their acoustic impedance spectrum measured at the embouchure or 'input' to the instrument. The acoustic impedance Z is the ratio of acoustic pressure p U and its extrema identify the frequencies of resonances and antiresonances due to standing waves in the bore. (For example see [1].) Backus [2] reports measurements of the acou...

A method is developed for measuring acoustic impedance. The method employs a one-dimensional tube or duct with excitation at one end and an unknown acoustic impedance at the termination end. Microphones placed in the tube are then employed to measure the frequency response of the system from which acoustic impedance of the end is calculated. This method uses fixed instrumentation and takes adva...

Modeling the complex characteristic acoustic impedance and complex wavenumber of porous materials allows the prediction of the complex specific acoustic impedance of a system consisting of porous absorbers and air cavities in front of a rigid surface. By using the transfer matrix method, the complex characteristic acoustic impedance and complex wavenumber of a porous material can be predicted b...