1. In an interactive computer system including a processor, an input device, an output and a sound generator, a method for training an individual user over the course of more than one session to discriminate between two sound stimuli, the method comprising: providing, by the computer system output to the individual user, a series of presentations of the two sound stimuli separated from each other by an interstimulus interval (ISI); receiving by the computer input device, as the series of presentations is provided, user inputs wherein each received user input is responsive to at least one presentation in the series and wherein each such received user input provides an indication of the individual user's ability to discriminate between the two stimuli; and decreasing, by the computer system, the ISI between the two sound stimuli in the random presentations as the individual's ability to discriminate between the two sound stimuli improves.