Acoustic observations in young children's non-cry vocalizations.

A corpus of 1200 non-cry vocalization samples produced by 14 normal children between the ages of 11-25 months was examined retrospectively. Six percent of the samples yielded instances of either harmonic doubling (HD), fundamental frequency (F0) shift, or biphonation (Bp). These spectrographic features relate to short duration changes in F0, reflecting alterations in vocal fold state characteristics. The HD and Bp segments were perceptually judged to be harsh, while F0 shift closely reflected pitch breaks. The frequency of occurrence of the three acoustic features suggests that they are normally occurring phonatory events in normal children's vocal patterns.