The typical speed of sound in bone is approximately:

• A. 3000 m/s
• B. 4000 m/s
• C. 3200 m/s
• D. 3500–4000 m/s

Answer: (D)

The speed of sound in bone is determined mainly by how stiff the tissue is and how dense it is. Bone, especially cortical bone, is very stiff and relatively dense, so waves travel much faster there than in soft tissues. For longitudinal waves traveling along the bone’s long axis, this stiffness-dense combination puts the velocity in the upper thousands of meters per second. Because bone properties vary with type (cortical vs cancellous), direction, age, and individual factors, a single fixed number isn’t representative. A typical, practical range that reflects this variability is about three and a half to four thousand meters per second. That’s why this option—the range from roughly 3500 to 4000 m/s—is the best match. It captures the common speeds observed in bone, whereas the smaller single values fall outside the usual bone velocity range.