Bilabial consonants are sounds produced by bringing both lips together to stop or restrict airflow. English bilabials include: /p/ (bilabial plosive, voiceless), /b/ (bilabial plosive, voiced), and /m/ (bilabial nasal). The word comes from Latin bi- (two) + labium (lip). Nasal sounds involve airflow through the nose; glottal sounds are produced at the glottis; affricates begin as stops and release as fricatives.