A new experimental rock deformation system utilizing a piston-cylinder apparatus allows recording of microacoustic signals associated with rock failure with great accuracy over a bandwidth of DC-4MHz. A calibrated response makes possible the measurement of dynamic seismic parameters which may be compared with those predicted by theory. Preliminary analysis of two events generated during brittle shear failure of granite suggests that the strain drop of ~1¿10-4 is similar to that of large earthquakes. A seismic moment of 106 dyn-cm and corner frequency of 600 KHz are consistent, in a general way, with those expected from theory.