Linguolabial consonant


Linguolabials or apicolabials are consonants articulated by placing the tongue tip or blade against the upper lip, which is drawn downward to meet the tongue. They represent one extreme of a coronal articulatory continuum which extends from linguolabial to subapical palatal places of articulation. Cross-linguistically, linguolabial consonants are very rare. They are found in a cluster of languages in Vanuatu, in the Kajoko dialect of Bijago in Guinea-Bissau, in Umotína, and as paralinguistic sounds elsewhere. They are also relatively common in disordered speech, and the diacritic is specifically provided for in the extensions to the IPA.
Linguolabial consonants are transcribed in the International Phonetic Alphabet by adding the "seagull" diacritic,, to the corresponding alveolar or dental consonant. additionally suggest these sound may be equivalently transcribed with the apical diacritic,, on the corresponding bilabial consonant. However, reject this transcription, as linguolabials may be articulated either apical or laminal. The labial consonants have also been used. The choice of the base consonant may depend on whether the author analyses the linguolabial as being phonologically labial or alveolar.
By analogy of the distinction made between labiodentals and dentolabials, labiolinguals may be distinguished as consonants articulated by placing the bottom of the tongue tip or blade against the lower lip.

Description

Image:Linguolabial stop.png|thumb|Sagittal section of linguolabial stop
Linguolabials are produced by constricting the airflow between the tongue and the upper lip. They are attested in a number of manners of articulation including stops, nasals, and fricatives, and can be produced with the tip of the tongue, blade of the tongue, or the bottom of the tongue. Acoustically they are more similar to alveolars than bilabials. Linguolabials can be distinguished from bilabials and alveolars acoustically by formant transitions and nasal resonances.

Linguolabials as a diachronic stage in sound shifts

In Vanuatu, some of the Santo–Malekula languages have shifted historically from bilabial to alveolar consonants via an intermediate linguolabial stage, which remains in other Santo and Malekula languages.
While labials have become linguolabial before nonrounded vowels in various languages, the sound shift went further in languages such as Tolomako, which shifted the linguolabials to full alveolar consonants: *b > * > p̈ > t ; *m > m̈ > n . Thus, POc *bebe > later became in Tolomako. Likewise, POc *tama > > Tolomako.