Abstract: A nondestructive method for inspecting internal pressures of sealed containers wherein a magnetic impulsive force is impinged upon a metallic surface of the container and the resulting vibration of the metallic surface is detected. The detected signal is applied to a plurality of band-pass filters from which the fundamental and harmonics are extracted. The two highest level signals extracted from the band-pass filters, designated the fundamental and a harmonic, are selected, which signals are analyzed by comparison to predetermined values for level and frequency and for their ratio of their levels with respect to one another. A judgment as to the integrity of the sealed container may be made based upon the deviation from the aforesaid predetermined values.