Attenuation of Ultrasonic Waves in Solids

Abstract

So far ideal materials have been assumed in which the sound pressure is attenuated only by virtue of the spreading of the wave. A plane wave would thus show no attenuation whatever of the sound pressure along its path, and a spherical wave, or the sound beam of a probe in the farfield, would merely decrease inversely with the distance from the source. Natural materials, however, all produce a more or less pronounced effect which further weakens the sound. This results from two causes, viz. scattering and (true) absorption which can both be combined by the concept of attenuation (sometimes also called extinction).