Absolute pitch and tempo in mothers' songs to infants.

We examined the relative stability of pitch, tempo, and rhythm in maternal speech and singing to prelinguistic infants. Mothers were recorded speaking and singing to their infants on two occasions separated by 1 week or more. The pitch level and tempo of identical utterances were highly variable across the 1-week period, but these features were virtually unchanged in song repetitions. Rhythmic patterning was largely maintained in speech, as in song. Mothers' accurate reproduction of their sung performances can be considered a form of absolute pitch and absolute tempo.