Several studies have shown that when a talker is instructed to speak as though talking to a hearing-impaired person, the resulting "clear" speech is significantly more intelligible than typical conversational speech. While variability among talkers during speech production is well known, only one study to date [Gagné et al., J. Acad. Rehab. Audiol. 27, 135-158 (1994)] has directly examined differences among talkers producing clear and conversational speech. Data from that study, which utilized ten talkers, suggested that talkers vary in the extent to which they improve their intelligibility by speaking clearly. Similar variability can be also seen in studies using smaller groups of talkers [e.g., Picheny, Durlach, and Braida, J. Speech Hear. Res. 28, 96-103 (1985)]. In the current paper, clear and conversational speech materials were recorded from 41 male and female talkers aged 18 to 45 years. A listening experiment demonstrated that for normal-hearing listeners in noise, vowel intelligibility varied widely among the 41 talkers for both speaking styles, as did the magnitude of the speaking style effect. While female talkers showed a larger clear speech vowel intelligibility benefit than male talkers, neither talker age nor prior experience communicating with hearing-impaired listeners significantly affected the speaking style effect.