Presents methods, described for performing absolute and comparison calibrations of laboratory standard microphones specified in American Standard Specification for Laboratory Standard Pressure Microphones, Z24.8-1949. Absolute calibration is based upon the reciprocity principle. Techniques for performing pressure (coupler), free-field, and random-field calibrations are described, including experimental procedures. The free-field and random-field calibration techniques may also be used for calibrating microphones not described in American Standard Z24.8-1949.