Here is a typical result when measuring a tweeter:
We can read the tweeter's resonance frequency, F(s) (or, more strictly F(sc)), directly from the impedance plot or note the value at the Measured Parameters F(s) field. Just as with a closed box, the system's Q(tc) is read from the Q(ts) field. Similarly for the electrical and mechanical Q's. The above tweeter is seen to have a resonance of 1.848 kHz and Q(tc) of .5067.