OT: harmonizer control

[Michael Peters <mpeters@csi.com>]

just listened to a live recording of Nils Petter Molvaer who plays the 
trumpet in combination with a harmonizer, just as Jon Hassell does, and 
produces harmonies that often change while he sustains one single trumpet 
note. Even though I saw him live last year, I can't quite figure out how 
he 
does that - how he controls his harmonizer while he plays trumpet. With 
some kind of footpedal I guess, but how exactly? I could either imagine a 
midi pedal that sets various fixed harmonic presets, or for flexibility, 
maybe some kind of footpedal-keyboard like an organ player ... who does 
something similar and knows more about this specific technique?

=       michael peters
=       electronic music & strange attractors
=       http://www.mpeters.de/mpeweb