DESCRIPTION (from applicant's abstract): Considerable evidence indicates that the acquisition of laryngeal control in speech undergoes a rather protracted period of development and that systematic differences exist between children and adults in aerodynamic quantities and in some voice source characteristics. Aerodynamic data can provide information on some aspects of laryngeal behavior not evident in the acoustic signal. Few studies have exploited this fact, however, and there is a dearth of work on dynamic patterns of oral flow and pressure data from children. The proposed study will collect acoustics, oral airflow and intraoral pressure from children ages 4-5 and 9-10 and a control group of adults producing /b p h z s/ in short utterances. The inverse-filtered oral airflow signal will be measured for several periods before and after the consonants to determine whether children's voice source characteristics (open quotient, speed quotient, f0, pulse amplitudes) show consonantally-induced variations of magnitudes and durations similar to adults. Smoothed versions of the intraoral air pressure signals will be measured to determine the shape and temporal characteristics of the pressure pulse during bilabial closures as functions of age and consonant type (voiced versus voiceless). Finally, comparisons of the airflow signals in the fricatives /s/ and /h/ will be made to determine whether clear differences exist in the abduction patterns for the two sounds, and how children's laryngeal behavior and laryngeal-oral coordination compares to adults. Part of this analysis will use nonlinear normalization to obtain a representative average for each consonant in each subject and to investigate the time-varying patterns of variability over the course of the consonant. These analyses will extend previous work on laryngeal and voicing control in children, will supply data necessary for aerodynamic modeling of the developing vocal tract, and will allow the formulation of more specific hypotheses about the development of laryngeal and aerodynamic control.