Which sounds are critically directed into the nasal passages by lowering the velum?

Lowering the velum is a crucial action that allows airflow to pass into the nasal cavity, which is essential for the production of nasal sounds. These sounds, such as /m/, /n/, and /ŋ/ (as in 'sing'), require this open passage for resonance and articulation to occur properly. When the velum is lowered, it creates a coupling between the oral cavity and the nasal passages, enabling the distinct quality of nasal sounds. In contrast, other sounds—such as vowel sounds and various consonants—typically require the velum to be raised to direct airflow exclusively through the oral cavity for proper sound production. Thus, the act of lowering the velum is specifically associated with the generation of nasal sounds.