A higher acoustic impedance mismatch between two media will most likely result in

• A. Increased Transmission
• B. Stronger Reflection
• C. Decreased Reflection
• D. No Reflection

Answer: (B)

Sound energy behavior at a boundary is governed by how different the acoustic impedances of the two media are. Acoustic impedance, Z, is the product of density and sound speed, and the fraction of incident energy reflected at the boundary is determined by the reflection coefficient, which depends on the difference between the two impedances. As the mismatch between Zs grows, the reflection increases, with more energy bouncing back and less passing through. So a higher impedance mismatch will produce stronger reflection. If the impedances were identical, there would be no reflection and all energy would transmit; with small mismatches you get small reflections, and with large mismatches you get strong reflections.