The noise in a frequency demodulated audio signal is detected on basis of the characteristics of the stereo-multiplex signal to obtain a very reliable information that can be used for the sliding stereo-mono transition, noise blanking and a de-noising of the stereo-difference signal. The compositions can also contain microcrystalline cellulose, croscarmellose sodium, anhydrous lactose, magnesium stearate, micronized edetate calcium disodium hydrous, and micronized sodium thiosulfate pentahydrate. The present invention is applicable to memory card automatic locating and withdrawing.