Early maturation of frequency-following responses to voice pitch in infants with normal hearing

Neural plasticity of pitch processing mechanisms at the human brainstem, as reflected by the scalp-recorded frequency-following response (FFR) to voice pitch, has been reported for normal-hearing adults. Characteristics and maturation of such a response during the first year of life have remained unclear. The purpose of this study was to examine the characteristics of FFR to voice pitch in normal-hearing infants and to make a direct comparison with adults using the same stimulus and recording parameters. 9 infants and 9 adults were recruited. A Chinese monosyllable that mimics the English vowel /i/ with a rising pitch was used to elicit the FFR to voice pitch. The results demonstrated that infant FFRs showed slightly larger Pitch Strength but comparable Frequency Error, Slope Error, and Tracking Accuracy to those obtained from adults. Early maturation of FFRs was also observed in the infants starting from 1 to 3 mo. of age.