In behavioral experiments on bottle-nosed dolphins there was evaluated efficiency of identification of the low frequency noises that represent a certain rhythmical sequence of impulses, at destabilization of their spectra by method of frequency wobble. Results of the experiments have shown that disturbance of spectra structure at erosion of its discrete components does not lead to a decrease of efficiency of the noise identification, which indicates the greater significance of the time, rather than spectral mechanisms at processing of the complex acoustic signals by the dolphin auditory system.