Specular reflections occur when the sound wave strikes which type of surface?

Specular reflections occur when sound waves encounter a smooth and large surface that is relatively flat compared to the wavelength of the sound being emitted. This type of reflection happens because the angle of incidence equals the angle of reflection, allowing for efficient energy reflection in a predictable direction. The smoothness of the surface minimizes scattering of the sound wave, resulting in a clear return signal that enhances image quality in sonography.

In contrast, surfaces that are rough or smaller than the wavelength of the sound tend to scatter the reflections in many directions, resulting in diffuse reflections. This scattering reduces the intensity of the reflected signal and can lead to decreased image resolution. Weak reflectors generally do not return enough sound energy for a significant reflection to occur, while strong reflectors can provide an echo, but if they are not smooth, they may not yield a specular reflection, which is most identifiable on large, smooth surfaces.