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This study explored the physiological adjustments made by the speech mechanism when sustained maximum phonations and sentences differing in vocal loudness were produced by typically developing children and children with cerebral palsy (CP). Respiratory adjustments (lung volume initiation, termination and excursions), chest wall muscular amplitude adjustments (intercostal, obliques), vocal fold adjustments (speed quotient), fundamental frequency of selected vowel nuclei and area of mouth opening were calculated. A total of eight children (4 typically developing children, 4 children with CP) were studied. Results indicated that overall typically developing children adjusted lung volume initiation, lung volume excursion, intercostal and oblique muscle activity, speed quotient, fundamental frequency, and area of mouth opening to meet vocal loudness targets. In contrast, children with CP primarily adjusted intercostal and oblique muscle activity, speed quotient, and fundamental frequency to meet vocal loudness targets. / Speech-Language Pathology