Results of experiments on structure changes in historic stone monuments, using ultrasonic methods, showed that common examination, based on the measurement of ultrasonic wave velocity, only allows for average values which cannot be regarded as a base for further accurate analysis. Additional information can be obtained from the dispersion of ultrasonic waves shown in frequency domain with spectral analysis. More accurate values can be obtained from the transformation of binary generated ultrasonic pulses, analyzed with the so-called cubical model of inhomogeneous medium.