Which feature primarily characterizes consonants as opposed to vowels?

• A. Obstructed airflow through the vocal tract
• B. Free airflow through the vocal tract
• C. Nasal resonance
• D. Voicing difference

Answer: (A)

Consonants are defined by how the airflow is shaped in the vocal tract. When producing them, the airstream is obstructed in some way—there can be a closure or a narrow opening at places like the lips, teeth, palate, or glottis, which modifies or interrupts the air. That built-in obstruction is the hallmark that distinguishes consonants from vowels, where the vocal tract remains relatively open and air flows freely to produce sounds shaped mainly by the tongue and lips. While there are other features that can occur (like nasal resonance in some sounds or differences in voicing), the essential characteristic that sets consonants apart is the obstructed airflow through the vocal tract.