Abstract: As experimental phonetic materials,this paper uses some standard Chinese monofinals produced isolatedly by three groups of speakers of different sex or age.By means of acoustical and statistical analysis,three auditory preprocessing models of speech recognition,that contain some kinds of both auditory transformations and normalizations,are compared.Experimental resultsshow that Erb is the best one among auditory transformations,but no significant difference is found among these normalizations.Chistovich's SCG effect is verified,the critical distance between standard Chinese finals is estimated as 3.0 Bark or 3.5 Erb.