Teenagers often get made fun of for their one-word answers and grunts, but it turns out there could be a number of reasons for the tendency.
For one thing, researchers know that boys generally develop language skills later than girls, and this could be due to wiring in the brain. Another factor: boys have a smaller jaw opening than girls—a 2016 study found that women opened their jaws more widely when speaking than men did. As a result, the women were better at pronouncing low vowel sounds, while for men these sounds were more likely to be mumbled.
Dr. Genevieve von Lob, a clinical psychologist, adds that for most teens, mumbling is a result of the psychological, social, emotional and developmental changes that are happening in their bodies and lives, prompted by hormonal changes. She also says, “Many teenagers want more privacy so they become monosyllabic or prefer to text rather than talk as a way of trying to become more autonomous and independent. This is normal and perfectly healthy.”