Custom-molded earplugs (CMEPs) whose canal segments extend beyond the second bend of the ear canal can provide excellent attenuation but can sometimes be uncomfortable. Attenuation was measured for CMEPs whose canal segments were shortened in 2-mm increments. The within-subjects design permitted illustration of the form of the function relating attenuation to canal segment length for individual...

Transient hepatic attenuation difference (THAD) is a perfusion disorder that can sometimes be observed in hepatic arterial phase of a biphasic spiral CT examination. The involved site of liver by THAD appears as an area of high attenuation on the hepatic arterial phase image and returns to normal attenuation on portal venous phase image. The knowledge of the shape, distribution and causes of TH...

The primary objective is to obtain experimental measurements of the plane wave reflection coefficients from laboratory and in situ sediments using impedance tube [1] and acoustic resonator tube [2, 3] methods, in the frequency range of approximately 300 Hz to tens of kHz. This approach will also yield measurements of the acoustic impedance, sediment sound speed, attenuation, and complex density...

According to a recently developed theory of wave propagation in marine sediments, the dispersion relationships for the phase speed and attenuation of the compressional and the shear wave depend on only three macroscopic physical variables: porosity, grain size, and depth in the sediment. The dispersion relations also involve three (real) parameters, assigned fixed values, representing microscop...