The double resonance technique aims at removing the effect of spin‐spin coupling by the application of a strong rf field at the resonance frequency of the disturbing nucleus in addition to the weak rf field used for observation of the NMR spectrum. A method is described whereby the weak rf field is obtained by a small audio frequency modulation of the magnetic field strength. This method is applicable to chemically nonequivalent groups of hydrogen nuclei to simplify the interpretation of high resolution proton magnetic resonance spectra. Two examples are given.