Learning to identify talkers: Do 4.5-month-old infants distinguish between unfamiliar males?

Vocal recognition of socially relevant conspecifics is an important skill throughout the animal kingdom. Human infants recognize their own mother at birth, and they distinguish between unfamiliar female talkers by 4.5 months of age. Can 4.5-month-olds also distinguish between unfamiliar male talkers? To date, no adequately powered study has addressed this question. Here, a visual fixation procedure demonstrates that, unlike adults, 4.5-month-olds (N = 48) are worse at telling apart unfamiliar male voices than they are at telling apart unfamiliar female voices. This result holds despite infants' equal attentiveness to unfamiliar male and female voices.