Sound traveling in bone undergoes extensive ______.

• A. Absorption
• B. Reflection
• C. Scattering
• D. Refraction

Answer: (A)

The main idea here is attenuation of ultrasound in dense, mineralized tissue. Bone is highly mineralized and viscous, so as sound moves through it, most of the energy is quickly converted into heat by internal friction and the viscous losses in the bone matrix and fluid. This absorption causes the wave to lose energy rapidly, leading to strong attenuation as it travels. While reflections at interfaces and some scattering can occur due to impedance contrasts and the bone’s porous structure, they don’t account for as much energy loss inside the bone as absorption does. Refraction requires a speed change at an interface and isn’t the primary mechanism of loss within the bone itself. So sound undergoing extensive attenuation in bone is mainly due to absorption.