A method on a computing device for determining a psychophysical threshold regarding an aging adult's ability to temporarily store and retrieve an order of the syllables by requiring the adult to listen to two or more aurally processed syllables, presented serially, view the syllables graphically, and designate the order in which the syllables were presented. Two tracks are initialized to respective stage values, each corresponding to attributes of the presented syllables. A number of trials are performed according to each of the two tracks. As the adult attempts to determine the syllable order in trials, correct/incorrect selection of an order causes the stage value of a track to be adaptively reduced/increased, using a maximum likelihood procedure, e.g., ZEST, where the two tracks are adjusted until their values substantially converge, or a specified number of trials is performed. The final stage values of the tracks are averaged to determine the threshold.