How do sound waves in a Bose-Einstein condensate move so fast?

Low-momentum excitations of a dilute Bose-Einstein condensate behave as phonons and move at a finite velocity v(s). Yet the atoms making up the phonon excitation each move very slowly; v(a)=p/m-->0. A simple "cartoon picture" is suggested to understand this phenomenon intuitively. It implies a relation v(s)/v(a)approximate toN(ex), where N-ex is the number of excited atoms making up the phonon. This relation does indeed follow from the standard Bogoliubov theory.