Pitch and communicative intent in mother's speech: Adjustments for age and sex in the first year

This study investigated pitch and communicative intent in mothers' infant-directed speech spoken to their infants at birth, 3, 6, 9, and 12 months. Audio recordings of mothers (6 with female, and 6 with male infants) talking to another adult and to their infant at 5 ages were low-pass filtered and rated by 60 adults on 5 scales (Positive or Negative Affect, Express Affection, Encourage Attention, Comfort or Soothe, and Direct Behavior). Mean fundamental frequency (F-0) and pitch range of utterances were also measured. Utterances associated with positive affect tend to peak at 6 and 12 months, whereas more directive utterances peaked at 9 months. Mean F-0 followed the age trend for affective utterances, and pitch range followed the trend for directive utterances. The results suggest mother speech patterns reflect, complement, and perhaps facilitate infant development.