A method on a computing device is provided for enhancing the memory and cognitive ability of an older adult by requiring the adult to differentiate between rapidly presented stimuli. The method utilizes a sequence of phonemes from a confusable pair which are systematically manipulated to make discrimination between the phonemes less difficult or more difficult based on the success of the adult. The manipulation includes processing of the consonant and vowel portions of the phonemes by emphasizing the portions, and/or by stretching the portions. Further processing includes separating the consonant and vowel portions by time intervals. As the adult improves in their auditory processing, the discriminations are made progressively more difficult by reducing the amount of processing to that of normal speech.