The entropy theory of perception has been developed from principles of information theory and predicts both psychophysical data and firing rates of sensory receptors or primary afferents. It has demonstrated how mathematical relationships subsist among many previously unrelated phenomena, such as adaptation processes, reaction times and subjective magnitudes and can be applied to most modalities of perception. The current study demonstrates how the theory can be applied to intensity discrimination of auditory pure tones. A psychophysical experiment of intensity discrimination was carried out under computer control in three practiced normal hearing listeners. Three different derivations for the entropic description of intensity discrimination were applied to the data and analyzed in terms of computer generated best-fitting parameters. The physiological meaning of these parameters is discussed.