Abstract
Spectral analyses were applied to the courtship songs of the mutantscacophony (cac), dissonance (diss), fruitless (fru), andperiod (per), as well as to the double mutantcac diss. Aberrant intervals between song pulses were observed indiss, cac, cac diss, andfru songs,diss males displayed a defect in song hums manifested by an irregular sine wave, although the fundamental frequencies were normal. Sine song frequencies and intrapulse frequencies were aberrant incac diss males. Two per mutant alleles (per o1 andper s) were associated with normal seng pulses and hums. These findings are discussed with regard to the mechanisms of song production and the role of these sounds inDrosophila reproduction.