I've learned through course lectures that infants can recognize faces shortly after birth (Slater & Quinn, 2001), and have a visual preference for human features as young as 1-month-old (Sanefuji et al., 2011)[pdf]. Infants are also known to prefer hearing their mother's voices (DeCasper & Fifer, 1980) and motherese (Fernald,1984). Prefences for higher-pitched singing also suggests that babies may in general prefer higher pitches (Trainor & Zacharias, 1997).
In general I would like to know more comprehensively what types of sound preferences do young infants have? And when is the youngest age for which these preferences are observed?