Complex sentence: Puberphonia (also known as mutational falsetto) is characterized by the habitual use of a high-pitched voice after puberty once the vocal folds have reached adult size.
Split into simpler sentences: Puberphonia (also known as mutational falsetto) is the habitual use of high-pitched voice beyond puberty. Puberphonia is the functional, habitual use of high-pitched voice post puberty after the vocal folds have reached typical adult size.