Example 15:

As a more typical example of commonly used perforated sheet, let us repeat the calculation for Item #7 in Table 1 at a fre- quency of 8000 Hz. Here the hole diameter d is 0.063", the on-center spacing b of the holes is 0.125", and the sheet thickness t is 0.037". (Of the examples in Table 1, this one will yield the greatest self-resistance).

We find:

Ro1 = 0.88 cgs Rayls;
Ro2 = 0.11 cgs Rayls;
2~Ro = 1.48 cgs Rayls.

Again, Ro1 dominates.

Then:

R = 0.88 + 1.48 = 2.36;
R/pc = 0.58; and:
Xmax = 0.2.

As, suggested above, this value is about the highest that one would expect to find in typical perforated metal sheets. If the resonator were to be filled with any reasonable absorptive material, the acoustical performance would be governed by the filling, not by the self-resistance of the sheet.