ultrasonic in masked version am6

[Dzemoo]

why is there the same 18khz peak in the masked version of am6 as in the ultrasonic?

masked:


ultrasonic:

[Shannon]

There isn't. There is a spike at approximately the same place, but it's only a peak in the ultrasonic, because everything else is being filtered out. Also keep in mind that you may be getting environment al audio intermixing, since I don't have that spike on the masked.