Co-articulated consonants or complex consonants are consonants produced with two simultaneous places of articulation. They may be divided into two classes: doubly articulated consonants with two primary places of articulation of the same manner (both stop, or both nasal, etc.), and consonants with secondary articulation, that is, a second articulation not of the same manner.

Doubly articulated consonants

An example of a doubly articulated consonant is the voiceless labial-velar stop, which is pronounced simultaneously at the velum (a [k]) and at the lips (a [p]). In practically all languages of the world that have doubly articulated consonants, these are either clicks or labial-velars.

Consonants with secondary articulation

An example of a consonant with secondary articulation is the voiceless labialized velar stop has only a single stop articulation, velar [k], with a simultaneous approximant-like rounding of the lips. There is a large number of common secondary articulations. The most frequently encountered are labialization (such as ), palatalization (such as the Russian "soft" consonants like ), velarization (such as the English "dark" el ), and pharyngealization (such as the Arabic emphatic consonants like ).

Distinction between the two classes

As might be expected from the approximant-like nature of secondary articulation, it is not always easy to tell whether a co-articulated approximant consonant such as is doubly or secondarily articulated. In some English dialects, for example, is a labialized velar that could be transcribed as.

Similar phones

The glottis controls phonation, and works simultaneously with many consonants. It is not normally considered an articulator, and an ejective such as, with simultaneous closure of the velum and glottis, is not normally considered to be a co-articulated consonant.