The 9321 tool contains a single transmitter and dual receiver to record formation travel times. The full wave form data are also recorded simultaneously, along with near and far travel times, borehole-compensated delta time, calculated sonic porosity, receiver gains, near/far amplitudes and natural gamma. The tool operates at 24kHz and therefore the period is 41.7usec. The sonic or acoustic log uses the basic principle of sound waves traveling through a media. The Century sonic system uses a single transmitter and dual receiver system for recording the travel times of the formation. The receivers are spaced 0.9m and 1.2m from the transmitter. Therefore, a 0.3m calculation can be made to measure this interval transit time.