The number of teeth per mm of file decreases rapidly from about 30 teeth/mm for A. arboreus to about 17 teeth/mm for A. celerinictus. As the pulse rates increase for the three species—from about 70 p/s for A. arboreus to 130 p/s for A. muticus to 170 p/s for A. celerinictus it seems likely there are interesting interactions between carrier frequency, tooth strikes per pulse, and pulse duration but these were not measured in 1973.