Degree of sub-harmonic components in infant cries and in Down Syndrome children and children with dysphonia

According to different studies of the infant cry, the sub-harmonic components or double series of fundamental frequency as a rule does not occur in the crying of healthy neonates. An acoustic analysis was made of three samples of cry signal (continuous signal or several short phonations), and six phonations of the vowel /a/ by pre-school children with dysphonia and by school children with Down syndrome. This was a cross-sectional study of children (nine boys) of different ages and with different disorders, including voice disorders such as dysphonia which occurred without any other medical impairments, and the genetic disorder of Down syndrome. Acoustic analysis was made using MDVP, Kay Elemetrics Computer software, a Real Time Frequency Analyser Type 2123 (Bruel and Kjaer), and the EZ Voice Program for Voice Analysis (Voice Tek Enterprises, USA). Four different parameters were measured: fundamental frequency, jitter, shimmer and degree of sub-harmonic components. Also, the focus of this study was to find and explain, sub-harmonic components or bi-phonation, as an indicator of voice or other pathology. Descriptive statistics of the acoustic data were obtained through Statistica for Windows, version 4.5.