This paper presents preliminary results from experimental research concerning the ultrasonic reflectivity of rock samples. The goal is to determine whether meaningful petrophysical properties can be obtained through the analysis of reflected acoustic signals of the type produced with the new generation of ultrasonic borehole televiewers. Present emphasis is on analysis of the full-reflected waveform. Time-domain samples of the transmitted and reflected signals are transformed into the frequency domain by means of digital Fourier methods to determine the complex reflection coefficient of the rock A simplified viscoelastic wave-propagation model converts the reflection coefficient estimates into wave velocity estimates. Sound speed estimates in reasonable agreement with those determined by use of standard experimental techniques have been obtained for a variety of sandstone samples. Signal-processing techniques for the analysis of waveforms recorded in an attenuating mud-filled borehole have been developed and tested in the laboratory.