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A method of, and apparatus for, enciphering and deciphering audio information which is subdivided into partial blocks along a time axis, the partial blocks being mutually interchangeable according to key information. The incoming analog audio signals are subdivided into a number of frequency bands, each of which is assigned to an information channel. The analog audio signals of each information channel are converted into digital signals which are subdivided into main blocks along the time axis. The main blocks of equal time of each information channel are subdivided into sub-sections of the same magnitude with respect to time and which are interchanged, in accordance with the key information with sub-sections of the same main block or with sub-sections of a time-equal (i.e. isochronal) main block of another information channel. After the interchange in each information channel, the digital signals are converted into analog signals and the interchanged sub-sections are group together into new main blocks, in order to render possible a further processing of the time-equal or isochronal new main blocks of each information channel.