Figure 6.

Comparison of differences between SPL_terminal and IPL_entrance resulting from different values of characteristic impedance ($Z_{0,8}$, ${\hat{Z}}_0$, and $Z_{0,d}$). Each characteristic impedance value was used to determine FPL and RPL of the set of test cavities with equal lengths and variable diameters (Table TABLE I., column 1). Shaded areas enclose the minimum and maximum of differences between SPL_terminal and IPL_entrance across test cavities obtained for each characteristic impedance condition. When cavity-specific characteristic impedance was used (${\hat{Z}}_0$ or $Z_{0,d}$), errors did not systematically increase with cavity diameter and were generally below 2.5 dB through 10 kHz and below 4 dB through 18 kHz.