Connect a PassThrough unit to the input ports of the voices so that they can be controlled
together using a single port. Note that this will prevent their individual use. So the
"Frequency" and "Amplitude" ports are excluded. Note that this method is a bit funky and is
likely to change.
public void exportNamedInputPort(java.lang.String portName)
Create a UnitInputPort for the circuit that is connected to the named port on each voice
through a PassThrough unit. This allows you to control all of the voices at once.