The 'ng' sound /ŋ/ as in 'sing' or 'ring' is a velar nasal consonant. It is classified as a nasal sound because air flows through the nasal cavity while the oral cavity is blocked. The velum (soft palate) is lowered to allow nasal airflow. Bilabial sounds involve both lips (/p/, /b/, /m/); uvular sounds are produced at the uvula.