The horn-like lead textures on "4 Winds" have the VL70m on top of various samples in the Wavestation. The Wavestation provided the groove and percussion sounds.

The groove was on MIDI channel 1 with other sounds on channels 2 , 3, and up.
Then on the Synthophone, the Thumb-X-press was set to switch between channels.
This allowed Randy to play an " obligato voice "over the triggered groove.

The data from the breath interacted with elements of the groove, bringing out different drum sounds relative to breath pressure.

Also, the lip pressure controls the tambourine sound.

Finally, the number of voices were varied in real time by " keying in " 1, 2, or 3 added notes.
The Synthophone was in " multi-channel mode "
So, each added voice went to the next higher MIDI channel.

Also in a 12-space rack, was a Yamaha TG500, VL70m, a Roland JV1080, and an EMU Audigy. Throughout the show, you can hear them in various layers for lead sounds and string/choral pads.

Berke is especially good at this function, because he's also a bass player.  With the bass concept in mind, his transfer of bass ideas to the Synthophone sound that much better.