Estimation of formant frequencies in infant cry.

The formant frequencies (F1, F2, F3) of normal infant crying were measured using three different estimation techniques: sound spectrography, linear predictive coding (LPC), and power spectrum analysis. Results found all three techniques to be highly similar for estimation of F1. However, the techniques differed significantly in the estimation of F2 and F3. Power spectrum analysis tended to yield the highest F2 and F3 values, while LPC consistently provided the lowest F2 and F3 values. Based on the results of the study, serious questions arise whether formant estimates of cry are accurate or appropriate for use as a metric of infant vocal tract resonance.