Consistent with social agency theory, we hypothesized that learners who studied a set of worked-out examples involving proportional reasoning narrated by an animated agent with a human voice would perform better on near and far transfer tests and rate the speaker more positively compared to learners who studied the same set of examples narrated by an agent with a machine synthesized voice. This hypothesis was supported across two experiments, including one conducted in a high school computer classroom. Overall, the results are consistent with social agency theory that posits that social cues in multimedia messages, including the type of voice, can affect how much students like the speaker and how hard students try to understand the presented material.