The influence of cyclic ambient sound stimuli on sexual development was studied in nonphotostimulated [6 hr light:18 hr dark (16L:18D)] Japanese quail (Coturnix coturnix japonica). The incidence of accelerated gonadal development was reduced when ambient daily sound stimuli were attenuated by the presence of a white noise mask in the animal quarters. In a second experiment nonphotostimulated (9L:15D) male quail showed a phase-dependent testicular response to a daily 3-hr radio broadcast presented at different portions of the day. The radio sound stimulus induced a higher incidence of accelerated gonadal development when presented 6 hr prior to the photophase than when presented either 3 hr prior to the photophase or when presented coincidently with the photophase onset. In a third experiment locomotion was monitored in nonphotostimulated quail (9L:15D) with a 3-hr radio sound stimulus presented 6 hr prior to photophase onset. The onset of a daily locomotor activity pattern was associated with radio sound in some individuals, but sound-induced locomotion was not consistently associated with sound-induced accelerated gonadal development.