Abstract: The invention is a carriage type sonic or ultrasonic testing apparatus for flaw and deterioration detection testing in a structure, especially concrete. The apparatus detects both location and type of flaw in a structure. The carriage unit incorporates a rolling pond feature which includes: i) foam-covered tracks and rollers, this soft foam material in addition to its primary function prevents vibration of the transducers while traversing rough surfaces such as weathered concrete. The tracks and rollers form a water-tight seal with each other and the specimen surface; ii) an air-removal brush assembly which maintains contact with a specimen surface to facilitate transmission and reception of ultrasonic energy into and out of a test specimen; iii) an ultrasonic isolator element and optional wave absorbers; and iv) the ultrasonic transducer suspension system. A transducer water bed is continuously maintained while the system is in motion across the concrete.