At a solid reflecting boundary, sound pressure doubles while velocity drops to zero.

Evidence

Figure 1.23 shows this effect using our golf ball and spring model. One interesting effect occurs due to the fact that the wave has to change direction and to the fact that the spring connected to the immovable boundary is com­ pressed twice as much compared with a spring well away from the boundary. This occurs because the velocity components associated with the reflected (bounced back) wave are moving in contrary motion to the velocity compo­ nents of the incoming wave, due to the change of phase in the reflected velocity components. In acoustic terms this means that while the velocity component at the reflecting boundary is zero, the pressure component is twice as large. — David Howard, Jamie Angus, coustics and Psychoacoustics, 346

Categorization

• DEFINE: Explains the phase relationships that produce a pressure-doubling hard boundary reflection.