Improvement in interaural phase difference (IPD) discrimination over 2 to 3 h was compared for two two-alternative forced-choice paradigms: A three-interval paradigm, in which the IPD was in interval two or three, and a paradigm with two intervals of four stimuli in which the IPD was in the second and fourth stimuli of one interval (AAAA vs ABAB). The difference in performance between the beginning and end of the testing period was smaller for the two-interval paradigm, supporting the use of this paradigm for fast measurement of discrimination thresholds without the need for a long period of training.