What happens when you image a structure with oblique incidence?

What happens when you image a structure with oblique incidence?

• A. The angle of reflection will be oriented away from the transducer, resulting in decreased visualization.
• B. A very strong reflection will occur.
• C. All of the sound will be transmitted.
• D. The amount of scattering will be reduced.

Answer: (C)

When a sound wave hits a boundary at an angle, energy is divided rather than all of it passing straight through. Part of the energy is reflected back toward the transducer, creating echoes, and part is transmitted into the second medium, where the beam is typically refracted (its path bends) according to the speeds in the two media. The exact split depends on how different the acoustic impedances are and on the incidence angle. Because of this, you don’t get all of the sound transmitted at oblique incidence. The reflected portion can be significant if there’s a mismatch, and the transmitted beam is directed differently, which affects how the structure appears on the image. In short, oblique incidence causes both reflection and transmission with refraction, not complete transmission of the sound.

When a sound wave hits a boundary at an angle, energy is divided rather than all of it passing straight through. Part of the energy is reflected back toward the transducer, creating echoes, and part is transmitted into the second medium, where the beam is typically refracted (its path bends) according to the speeds in the two media. The exact split depends on how different the acoustic impedances are and on the incidence angle.

Because of this, you don’t get all of the sound transmitted at oblique incidence. The reflected portion can be significant if there’s a mismatch, and the transmitted beam is directed differently, which affects how the structure appears on the image. In short, oblique incidence causes both reflection and transmission with refraction, not complete transmission of the sound.