Ultrasonic Pulse Echo Technique has been used successfully as a practical modality for nondestructive testing of concrete to localize defects which cause critical infrastructure problems. However, in this highly attenuating medium, only limited penetration can be obtained using high frequency ultrasonic signals. Furthermore, ultrasonic signals from defects are corrupted by the echoes from randomly distributed scatterers, which generally result in significant background noise. Therefore, even when sufficient penetration is achieved, it is often cumbersome, if not impassible, to distinguish flaw signals from the background microstructure noise, corresponding to complex, dispersive and nonhomogeneous reflectors. To enhance flaw visibility, a well-known frequency diversity technique, namely Split Spectrum Processing (SSP) is employed.