First, let me agree with the notion that through interference of the supersonic
elements,
audible artifacts through reverberation can come into existence. The early reverb can
easily transfer some energy into the audio band and the (partially non-linear) reverb tail
of any non-dead listening
Using linear ramps going synchronously from 1 to 0 and 0 to 1 as
amplitude factors for each respective source should work fine.
Multiply your inputs by these signal ramp values and add the results
while crossfading.
That's it !
To ensure constant volume (e.g. if when cross-fading between two
