An electronic apparatus (1) supported against a dog's skin to control vocalizing by the dog electronically converts the vocalizing into a sequence of signals representing frequencies of the vocalizing, and operates a controller to determine if each measured frequency lies within any of a plurality of predetermined frequency sub-ranges and if so, increments cumulative totals of the frequencies which lie in the sub-ranges, respectively, to provide a plurality of cumulative totals that represent a frequency spectrum of the vocalizing. The controller is operated to determine whether the barking sounds constitute a valid bark by comparing the frequency spectrum to a predetermined valid bark frequency spectrum. Appropriate aversive stimulus signals are produced between first and second stimulus electrodes if the vocalizing sounds constitute a valid bark.