Emotional tone of voice indicates the significance of a spoken utterance. We asked whether listeners recognize this significance even when attending to something else and whether men and women differ in this regard. To answer these questions, we presented emotionally or neutrally spoken syllables as standards and deviants in a mismatch negativity paradigm. Independent of the listeners' sex, deviants elicited a mismatch negativity in the scalp-recorded event-related potential as an indicator of preattentive acoustic change detection. Only women, however, showed a larger mismatch negativity to emotional than to neutral deviants. Thus, even though both sexes detect change in voice preattentively, only women recruit additional processing resources when the change in voice is one of emotional valence.