Here is an excellent description of Indian improvisation that translates nicely to other styles and forms. This guy explains the improvisation process of an Alap very poetically and romantically. This also translated to call and response in a blues, jazz, or rock setting. Once again this speaks to the communication going on during an ensemble improve through music more than visual cues.
Here is a very nice example of an Alap.
At 4:17 some of the greatest call and response improv of all time.