Certain species of anurans and electric fish detect amplitude modulations as a means of identifying conspecifics and foreign objects, respectively. This paper provides an account of the similarities between the electrosensory and auditory systems in terms of the mechanisms by which this temporal information is analyzed. Both animals employ a temporal filtering mechanism in this analysis. The transformation from a periodicity coding of amplitude modulations by the peripheral nervous system to a temporal-filter analysis in the central nervous system appears to be present in a number of different animals, ranging from crickets to cats. The possibility of a similar temporal filtering mechanism in humans and its role in perception are discussed.