An acoustic probe calibration system includes a waveguide and a moveable piston. The waveguide extends from a front end to an opposite back end along a longitudinal axis and defines a cavity extending from the front end to the back end. The piston is disposed within the cavity of the waveguide and is configured to move within the cavity of the waveguide along the longitudinal axis of the waveguide. An acoustic probe is inserted into the waveguide to define an interior chamber between the acoustic probe and the piston. The acoustic probe determines pressure responses to acoustic stimuli inside the interior chamber. The piston is moveable to a plurality of different positions within the waveguide to change a size of the interior chamber such that the acoustic probe can determine the pressure responses within the varying-size interior chamber.