When do specular reflections occur?

Specular reflections occur when the interface between two media is larger than the wavelength of the ultrasound wave. In this scenario, the waves interact with the surface, allowing for a more organized reflection similar to how light reflects off a mirror. This is because a larger interface provides a sufficient area for the ultrasound wave to bounce back in a uniform direction, thereby producing a strong and well-defined reflection.

When the interface is larger than the wavelength, the reverberation of the sound waves occurs in such a way that the majority of the energy is reflected back to the transducer. This causes a high-amplitude echo, which is essential for producing clear and distinct images in ultrasound imaging. For effective imaging, specular reflections are favored as they provide valuable information about boundaries between different tissues or structures in the body.

In scenarios where the interface is smaller than or equal to the wavelength, the resulting reflections are diffuse or scattered rather than specular. These smaller interfaces do not reflect sound waves effectively, leading to poor image quality as the echoes may be weak and spread out. This is why understanding the size of an interface in relation to the wavelength is critical for interpreting ultrasound images.