Reflection phase at a boundary depends on whether acoustic impedance rises or falls

Evidence

To summarize, reflection from a solid boundary results in a reflected pressure component that is in phase with the incoming wave, whereas reflection from a bounded to unbounded region results in a reflected pres­ sure component which is in antiphase with the incoming wave. This arises due to the difference in acoustic impedance at the boundary. In the first case the impedance of the boundary is greater than the propagating medium and in the second case it is smaller. — David Howard, Jamie Angus, coustics and Psychoacoustics, 353

Categorization

• DEFINE: Defines the acoustic consequence of impedance mismatch at boundaries — phase inversion versus non-inversion.
• XREF: Connects to impedance matching ideas elsewhere in acoustics and in transmission-line theory. — connects to: Snow grounds require a layered porous-medium impedance model. — Donald G. Albert and John A. Orcutt, Acoustic Pulse Propagation Above…, 26