Doubly articulated consonants are consonants with two simultaneous primary places of articulation of the same manner (both plosive, or both nasal, etc.). They are a subset of co-articulated consonants. They are to be distinguished from co-articulated consonants with secondary articulation; that is, a second articulation not of the same manner. An example of a doubly articulated consonant is the voiceless labial-velar plosive [k?p], which is a [k] and a [p] pronounced simultaneously. On the other hand, the voiceless labialized velar plosive [k?] has only a single stop articulation, velar ([k]), with a simultaneous approximant-like rounding of the lips. In some dialects of Arabic, the voiceless velar fricative [x] has a simultaneous uvular trill, but this is not considered double articulation either.
|Places of articulation|
There are four independently controllable articulations that may double up in the same manner of articulation: labial, coronal, dorsal, and pharyngeal. (The glottis controls phonation, and works simultaneously with many consonants. It is not normally considered an articulator, and an ejective [k'], with simultaneous closure of the velum and glottis, is not considered a doubly articulated consonant.)
Approximant consonants, such as [w] and [?], may be either doubly or secondarily articulated. For example, in English, /w/ is a labialized velar that could be transcribed as , but the Japanese /w/ is closer to a true labial-velar [?]. However, it is normal practice to use the symbols ⟨w⟩ and ⟨?⟩ for the labialized approximants, and some linguists restrict the symbols to that usage.
No claims have ever been made for doubly articulated flaps or trills, such as a simultaneous alveolar-uvular trill, *[r], and these are not expected to be found. Several claims have been made for doubly articulated fricatives or affricates, most notoriously a Swedish phoneme which has its own IPA symbol, . However, laboratory measurements have never succeeded in demonstrating simultaneous frication at two points of articulation, and such sounds turn out to be either secondary articulation, or a sequence of two non-simultaneous fricatives. (Despite its name, the "voiceless labial-velar fricative" [?] is actually a voiceless approximant; the name is a historical remnant from before the distinction was made.) Such sounds can be made, with effort, but it is very difficult for a listener to discern them, and therefore they are not expected to be found as distinctive sounds in any language.
Clicks are sometimes said to be doubly articulated, as they involve a coronal (more rarely labial) forward articulation, which defines the various 'types' of clicks and the IPA letter assigned to them, plus a dorsal closure. However, this second, dorsal place of closure functions as part of the controlling mechanism of the lingual ingressive airstream used to generate the click. Thus, much as the glottal closure of ejectives (the airstream-generating mechanism of such consonants) is not considered to be a second place of articulation, clicks are not generally described as such either. Indeed, it is possible to have a true doubly articulated click, such as the labial-dental allophone, , of the bilabial click /?/ in Taa.
This leaves stops, and both oral and nasal doubly articulated stops are found. However, there is a great asymmetry in the places of their articulation. Of the six possible combinations of labial, coronal, dorsal, and pharyngeal, one is common, and the others vanishingly rare.
Triply articulated consonants are only attested as glottalized doubly articulated consonants, and this can be argued to be an effect of phonation or airstream mechanism rather than as a third articulation, just as other glottalized consonants are not considered to be doubly articulated. The most obvious case are the various types of glottalized clicks mentioned above. Another example is 'unreleased' final /k/ in Vietnamese, which after /u/ or /w/ is often labial-velar [k?p].