What is the speed of sound in bone tissue?

• A. 1,560 m/s
• B. 1,600 m/s
• C. 1,700 m/s
• D. 3,500 m/s

Answer: (D)

The speed of sound in a material is set by how stiff it is relative to its density. In solids, especially something as stiff as cortical bone, the elastic resistance to compression is very high, while the density is not prohibitively large. This combination makes longitudinal waves travel much faster in bone than in softer tissues. Cortical bone typically supports speeds around several thousand meters per second; a commonly cited value is about 3,500 m/s. That’s why this option matches bone’s properties so well. In contrast, soft tissues and fluids have much lower stiffness, giving speeds near 1,500–1,700 m/s, which is why those lower numbers don’t fit bone.