These are the measurements of a tweeter with membrane, which is made of unique material - Bio-Cellulose. This tweeter was been using in legendary vintage loudspeakers SONY SS-A5. You can learn more about these loudspeakers here.
The THD measurements at voltage levels 2 - 2.83 V were carried out with High Pass Filter "on" (2nd order Butterworth type, 800 Hz cutoff, HPF2-800)
The THD measurements at voltage levels 4 - 5.6 V were carried out with High Pass Filter "on" (2nd order Butterworth type, 1200 Hz cutoff, HPF2-1200)
The THD measurements at voltage level 8 V were carried out with High Pass Filter "on" (4th order Butterworth type, 1200 Hz cutoff, HPF4-1200)