The cross-hole sonic logging purpose is same as pile integrity test. If defect is much bigger than integrity do not provide any result. In such situation cross-hole sonic Logging is performed. By lowering sensors in cast in tube and sending a sonic signal through the concrete by the transmitter to the receiver, information about possible defects and concrete area over the cross sectional area will be obtained. Cross-hole Sonic Logging is mainly used for bored piles with large diameters and diaphragm walls, slurry wall.