The present invention provides a method making stratified paper by redistributing
the pulp suspension inside the headbox nozzle using acoustic radiation waves. Acoustic
radiation forces fractionate fibers based on fiber radius. The acoustic radiation
waves separate the fibers by pushing the coarse and longer fibers to the inner
area while fines and smaller fibers remain in the outer area. This has a similar
effect of multi-layer stratification headbox, and provides paper with a smoother surface.
