A musical note produced through the vibration of a single string is psychoacoustically simpler/purer than that produced via multiple-strings vibration. Does the psychoacoustics of instrument sound have any effect on learning outcomes in music instruction? This study investigated the effect of two psychoacoustically distinct instrument sounds on pitch discrimination achievement of college music students. Repeated-measures analysis revealed a significant difference between achievement scores of students by instrument sounds, which indicated that psychoacoustic complexity of instrument sound could affect learning outcome in music instruction. (Contains 5 tables and 3 figures.)