Megavoices are professionally played Midi loops which get additional variations when notes outside their range are played, but not heard by the user.
I would guess that something similar will occur with the arranger style system mentioned in the patent.
To achieve this it would not need any specialised hardware, as it could all be done in software, and while it could not be added to existing hardware boards due to the current limited amount of Flash Rom that is onboard, this will change in the future as Flash Rom gets larger and cheaper.
Patents are designed for lawyers and designers, so don’t expect it to give any description for the person in the street to be able to understand it. (At least not until it is pre-production)
Regards

Bill