Hey guys!
If you’re using the ultrasonic version you might want to use another spectrum analyzer to see if your device can play properly the sounds at 20k. I checked with another and it seems the loudest noise from my phone comes at 17.6k-18.2k and that’s the noise I am actually hearing (it seems my ears are not as good as I thought) and you can mark the 20k mark to see how loud that section actually is. For me it’s around 12-15 db lower than the actual noise