Ultrasonic wave scattering from ellipsoidal and cylindrical cavities embedded in titanium was measured and analyzed with a newly designed signal processing system. Using an immersion system and samples with flat faces, the range for waves incident, at certain polar and azimuthal angles,was determined for both L-L and L-S scattering. Attempts were made to define key parameters from both amplitude and phase spectra for characterizing cavities. Results are compared to predictions of Born approximations (developed by Krumhansl et al. at Cornell) and to experimental results taken by a contact system . A new (Keller type) theory for crack-like defects which includes mode conversion will also be presented.