When interaction is organized, the sound back to the transducer is ______.

When interaction is organized, the sound back to the transducer is ______.

• A. Backscatter
• B. Diffuse
• C. Rayleigh scattering
• D. Specular

Answer: (D)

When the boundary is smooth on the scale of the ultrasound wavelength, the reflection behaves like a mirror. The incident sound reflects with the angle of incidence equal to the angle of reflection, sending most of the energy straight back to the transducer and producing a bright, well-defined echo. If the boundary were rough or irregular, the sound would scatter in many directions (diffuse scattering), and the return to the transducer would be weaker and more smeared. Rayleigh scattering describes small scatterers causing a broad, weak pattern, not the organized, mirror-like return. So, organized interaction yields a specular backscatter toward the transducer.

When the boundary is smooth on the scale of the ultrasound wavelength, the reflection behaves like a mirror. The incident sound reflects with the angle of incidence equal to the angle of reflection, sending most of the energy straight back to the transducer and producing a bright, well-defined echo. If the boundary were rough or irregular, the sound would scatter in many directions (diffuse scattering), and the return to the transducer would be weaker and more smeared. Rayleigh scattering describes small scatterers causing a broad, weak pattern, not the organized, mirror-like return. So, organized interaction yields a specular backscatter toward the transducer.