I think the point is that some people assert that they want the ultrasonics, as if they could tell the difference, so you wouldn't filter it. Then the presence

I think the point is that some people assert that they want the ultrasonics, as if they could tell the difference, so you wouldn't filter it. Then the presence of those ultrasonic tones creates the modulation in a range that you can hear. Likewise, the 60dB difference doesn't matter because you can't hear the signal at all, so you're going to notice the noise.