Figure 14:
The measured input impedance for the lowest note on an alto saxophone.
Typically measured with special-purpose probes using two or more microphones.
However, a few commercial sensors are available for musical acoustic applications (BIAS, CapteurZ), though they tend to be expensive.
Most probes require a calibration step, involving one or more measurements.
Changes in air temperature should be avoided, as they require recalibration.
It is important to avoid air leaks, which are sometimes hard to suppress. Blue gum or vaseline is useful for this purpose.
For an acoustic resonator, we would like our resonator to have as many harmonically aligned peaks as possible, with the fundamental being the strongest.
