Allen Forte's theory of pitch-class set structure has provided useful tools for discovering structural relationships in atonal music. As valuable as set—theoretic procedures are for composers and analysts, the extent to which set relationships are perceptible by the listener largely remains to be investigated. This study addresses the need for aural-perceptual considerations in analysis, reviews related research in music perception, and poses questions concerning the aural perceptibility of set relationships. Specifically, it describes and presents the results of a computer-assisted experiment in testing the perceptibility of set-equivalency relationships.