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 the
ejective , with simultaneous closure of the
velum and
glottis, is not considered a doubly articulated consonant.)
Approximant consonants, such as and , may be either doubly or secondarily articulated. For example, in
English, is a labialized velar that could be transcribed as , but the
Japanese is closer to a true labial–velar . However, it is normal practice to use the symbols 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, , 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. 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 click and IPA letter variants 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, and 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. ==Double articulation in stops==