An apparatus and method for characterizing cavitation that occurs in a fluid exposed to acoustic energy. A setpoint braking torque is set on the braking device, which is less than the required braking torque, and the part of the drive torque supplied to the first axle is increased. The lower electrode 7 includes a crossover region 7C crossing over a peripheral edge of the top surface portion of the pressure chamber 5 in a plan view. A female connector is provided and includes a base and a load bearing socket secured to the base of the female connector. Accordingly, such a semiconductor device can be fabricated easily in which a MOS type element and a bipolar element are formed on the same chip in a mixed manner. In one implementation a switching power supply and a linear regulator provide efficiency and rapid response.