Institute of Mechanics and Applied Computer Science, Kazimierz Wielki University, 85-064 Bydgoszcz, Poland.
J Acoust Soc Am. 2009 Dec;126(6):3301-10. doi: 10.1121/1.3257233.
The paper is focused on experiments on human cancellous bones filled with different fluids with the goal of evaluating their contribution to velocity dispersion, absorption, and scattering mechanisms. The specimens were measured first filled with marrow and subsequently, after marrow removal, with water and alcohol. No significant influence of the fluids was evidenced on the attenuation coefficient. Given the absence of impact of viscosity of the saturating fluid, the authors hypothesized that the source of attenuation is associated with viscoelastic absorption in the solid trabeculae and with scattering. Alteration of scattering obtained by changing the acoustic impedance mismatch between the fluid (alcohol vs water) and the trabeculae was reflected neither in the attenuation nor in its slope. This led the authors to suggest that longitudinal-to-shear scattering together with absorption in the solid phase are candidates as main sources for the attenuation. The differences in velocity values indicate that the elastic properties of the fluid are main determinants of the phase velocity. This finding is particularly significant in the context of /in vivo/ measurements, because it demonstrates that the subject-dependent properties of marrow may partly explain the inter-subject variability of speed of sound values.
本文专注于对填充有不同液体的人类松质骨进行实验，旨在评估它们对速度弥散、吸收和散射机制的贡献。首先测量了填充骨髓的标本，然后在去除骨髓后，用水分和酒精进行测量。结果表明，液体对衰减系数没有显著影响。鉴于饱和液体的粘度没有影响，作者假设衰减的来源与固体小梁的粘弹性吸收和散射有关。通过改变流体（酒精与水）和小梁之间的声阻抗失配来改变散射，这既没有反映在衰减中，也没有反映在衰减斜率中。这使得作者认为，纵波与横波的散射以及固体相的吸收是衰减的主要来源。速度值的差异表明，流体的弹性特性是相速度的主要决定因素。这一发现在体内测量的背景下尤为重要，因为它表明骨髓的个体差异特性可能部分解释了声速值的个体间变异性。
