The purpose of this test is to find the smallest discernible durational difference between two notes. To achieve this, each question involves two notes of duration d1 and d2, where d2 = d1 + d3 where d3 != 0. Participants listen to each of the notes separately after which they are expected to state which of the notes is longer in duration, whether the notes are of the same duration, or whether they do not know.

The durational values used have been chosen to reflect the commonly found ratios between musical note lengths of whole, half, quarter, eighth and sixteenth at a tempo of 120 quarter beats per minute. The order of presentation is based on a pre-determined random distribution.