Purpose: This investigation examined the effect of repeated exposure to novel and repeated spoken words in typical environments on the intelligibility of 2 synthesized voices and human recorded speech in preschools. Method: Eighteen preschoolers listened to and repeated single words presented in human-recorded speech, DECtalk Paul, and AT&T Voice Michael during 5 experimental sessions. Stimuli consisted of repeated and novel words presented in each speech output condition during each session. Sessions took place in the presence of typically occurring noise in classroom or home settings. Results: There was a significant main effect for voice as participants accurately identified significantly more words in the human-recorded speech and AT&T Voice than in the DECtalk speech output condition. When averaged across speech output conditions, children increased their accuracy as they participated in additional sessions. There was a statistically significant interaction between session and voice. DECtalk had a slightly larger effect of session than did AT&T Voice and human-recorded speech. (Contains 4 tables and 2 figures.)