1. A method of fitting a hearing assistance device for a user, comprising: presenting to the user using a computer stimulus pairs adapted to provide contrasting options for selection from a set of stimuli stored in the computer; receiving inputs from the user entered into the computer, including preference judgments of the user; calculating a score for each stimulus of the pair using the computer to execute a rank agreement function to maximize agreement between scores and the preference judgments; selecting a set of genes based on the scores, wherein the set of genes correspond to hearing assistance device parameters; and operating on the set of genes with a genetic algorithm using the assigned scores to obtain a child set of genes, wherein the child set is used to provide parameter values during fitting of the hearing assistance device.