The intense sound output at resonance in a laminated nickel bar is calculated from static measurements of the relationship of the free magnetostrictive strain to the intrinsic induction. The limitations of the linear theory are avoided by determining the dynamic magnetostrictive stress which is taken to be the motivating influence of the mechanical vibrations. The dynamic magnetostrictive stress is obtained by graphical methods that are not limited to small excitation amplitudes, as is the case in the linear theory. Simple relationships of the dynamic magnetostrictive stress to the impedances of the transducer load system enable the sound output to be determined from the calculated magnitudes of the magnetostrictive stress. The calculated sound output is compared with the sound output measured on a laminated bar of annealed nickel, resonating longitudinally at 20 kcps, and coupled to an acoustic load consisting of a half‐wavelength stub of highly dissipative cast iron. The sound energy delivered to the load is measured by a flow calorimeter, and mechanical transformers which are either solid exponential horns or stepped stubs are used to change the acoustic load to maximize the load power. The calculated sound outputs agree to within ±10% with the sound outputs measured calorimetrically. The measured maximum of the sound intensity is 167 w/cm2, while calculations show that 492 w/cm2ultimately can be generated with the annealed nickel. Estimated intensities for a more freely mounted specimen are in excess of 1 kw/cm2.