A large, flat, smooth surface tends to produce which type of reflection?

• A. Specular
• B. Voxel
• C. A-Mode
• D. Shadowing

Answer: (A)

Specular reflection happens when the boundary is large, flat, and smooth compared to the ultrasound wavelength. In this case, the incident wave reflects in a single direction with the angle of incidence equal to the angle of reflection, so most of the energy returns toward the transducer and you get a bright, well-defined echo at a specific depth. A surface that is rough on the scale of the wavelength would scatter energy in many directions, creating a weaker, diffuse echo and a less distinct interface. The other terms aren’t reflection types—voxel and A-Mode refer to data representations, and shadowing is an artifact from attenuation or obstruction rather than how the surface reflects the sound.