The field of this invention is classifying animal behaviors. In particular the fields of this invention include using animals in vivariums, such as rodents, particularly mice. Ultrasonic vocalizations of mice in a vivarium are compared to a predetermined set of positive phenotypes and to a predetermined set of negative phenotypes. The output of those comparisons are then compared to determine a metric of distance to classify vocalizations as closer to or more distant from elements of the positive or negative sets.