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It is shown that the entire Fermi surface can be mapped by using geometric resonances in the sound attenuation in tilted magnetic fields and the drift velocity of the carriers along the magnetic field simultaneously determined. The general features of the phenomena considered do not prove dependent on the particular models used in our calculations. In addition to the results specifically pertaining to tilted fields, when the assumptions of equal effective masses and relaxation times are dropped for a two band model of a semi-metal, the contribution of the two types of carriers to the ultrasonic absorption is additive. On examining the contribution to the absorption for a model of majority and minority carriers, the minority carriers dominate the attenuation when they are in the region of geometric resonances. (Author)