Labialization
Labialization is a secondary articulatory feature of sounds in some languages. Labialized sounds involve the lips while the remainder of the oral cavity produces another sound. The term is normally restricted to consonants. When vowels involve the lips, they are called rounded. The most common labialized consonants are labialized velars. Most other labialized sounds also have simultaneous velarization, and the process may then be more precisely called labio-velarization. In phonology, labialization may also refer to a type of assimilation process. Occurrence Labialization is the most widespread secondary articulation in the world's languages. It is phonemically contrastive in Northwest Caucasian (e.g. Adyghe), Athabaskan, and Salishan language families, among others. This contrast is reconstructed also for Proto-Indo-European, the common ancestor of the Indo-European languages; and it survives in Latin and some Romance languages. It is also found in the Cushitic and Ethio-Semitic languages. American English labializes to various degrees. A few languages, including Arrernte and Mba, have contrastive labialized forms for almost all of their consonants. Types Out of 706 language inventories surveyed by , labialization occurred most often with velar (42%) and uvular (15%) segments and least often with dental and alveolar segments. With non-dorsal consonants, labialization may include velarization as