Information concerning muscle mechanics has been derived largely from measurements obtained by attaching force transducers on coordinate systems to the ends of the muscle, thus the information derived is the integrated result of all the properties of all of the components of the muscle distributed along its length. The acoustic microscope is an instrument which may be applied to the study of muscle mechanics and instrumented with force transducers and quick stretch and release servos. This permits measurement of transverse properties as well as changes along the length of the muscle. There are several kinds of information which can be obtained using such instrumentation. Operating in the interference mode, the microscope can be used to measure changes in transit time through the specimen which can be related to changes in the acoustic velocity which, in turn, can be related to the adiabatic bulk modulus of elasticity. Changes in the transmission can be related to local changes in viscosity of the muscle during contraction. The microscope can also be used to measure dimensions in the x-y plane and along the z axis. Using the line-scan technique, rapid changes can be recorded. The line-scan rate is 15,750 lines per second, which is sufficient for resolving details of the contractile event.