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 (F0) 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 F0 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.