1. A voice recognition system comprising first means for periodically detecting the average frequency and average amplitude of at least a first voice signal to obtain a locus of the centroid of frequency spectra of said first voice, means for storing said locus, means for calculating a humming distance between a selected stored locus of the centroid of frequency spectra and a locus of the centroid of frequency spectra of a second voice detected by said first means, means for comparing said humming distance to a preselected value, a humming distance below said preselected value being accepted as an indication that both loci were detected from voice signals from a single person.