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For a comprehensive study of molecular interactions in multicomponent aqueous solutions, Raman spectroscopy is actively used. Herewith, for the correct interpretation of spectral data, it is necessary to know the mechanisms of formation of the vibrational bands. At present, the problem of the formation of a broad valence band of water, namely, the contribution of vibrations of water molecules with combination and resonance frequencies to its intensity remains relevant. This report presents the results of an experimental study of the role of Fermi resonance between the overtone of the bending vibration and the symmetric stretching vibration of water molecule in micellar solutions of sodium salts of monobasic carboxylic acids (surfactants). The analysis of broad spectral bands was carried out using genetic algorithms. Frequency detunings between the components of the Fermi doublet were obtained for all samples at room temperature. For solutions of sodium octanoate in the region of the critical micelle concentration (0.3-0.4 M), the frequency detuning sharply increases, which is explained by the strengthening of the network of hydrogen bonds in solution in the process of combining monomers and dimers of surfactants into multimolecular aggregates - micelles. The significant contribution of Fermi resonance to the intensity of the valence band of water in solutions of the studied surfactants is shown.