Boundary reflections

where represents the total number of boundary reflections, and is the reflection coefficient at the th reflection. The case with no reflections () corresponds to . Generally speaking, boundaries can be one of four types:

- Absorvent: the wave energy is transmitted completely to the medium above the boundary, so = 0 and ray propagation is terminated at the boundary.
- Rigid: the wave energy is reflected completely on the boundary, with no phase change, so = 1.
- Vacuum: the wave energy is reflected completely on the boundary, with a phase change of radians, so = -1.
- Elastic: the wave energy is partially reflected, with being a complex value and .

(4.2) |

where the units of attenuation should be given in dB/.

In general the reflection coefficient is real when
,
and the angle of incidence is less than the critical angle ,
with given by the expression

Orlando Camargo Rodríguez 2012-06-21