Description

Explanation

Reflection

When a wave reaches a medium of different acoustic impedance (interface), part of the wave energy is reflected into the incident medium. The angle of incidence and the angle of reflection are related by:

Refraction

When a wave reaches a medium of different propagation velocity, the transmitted wave undergoes an abrupt change in direction following the Snell’s law:

First critical angle

It is the angle of incidence that creates a 90º refracted longitudinal wave

Second critical angle

It is the angle of incidence that creates a 90º refracted shear wave (or Surface wave)

% Reflected energy (E)

Where Z1 and Z2 are the acoustic impedance of media 1 and 2 respectively. To calculate the % of transmitted energy, the reflected energy must be subtracted from 100%

Reflection coefficient

R is the reflection coefficient and it is a dimensionless numerical value.

Transmission coefficient

T is the transmission coefficient and it is a dimensionless numerical value.

Attenuation

Reduction in energy as a result of friction absorption and scattering as the wave travels through a material.

Pulse width (PW)

Duration of the high-voltage excitation pulse.