Reflections from a plane are
specular, meaning that they are well defined because of the regular geometry of the reflecting surface, as opposed to
diffuse, as in the case of an irregular reflecting object. In the latter case, the sound waves are reflected in many different directions. However, although a sphere reflects sound over a wide angle, as we shall see in
Sections 12.3 and 12.4, the reflection is specular because the reflecting surface is regular. Refer to
Fig. 4.11. A plane wave with amplitude
is incident on a plane at
x
=
0, the surface of which has a specific ...