Bilabial speech sounds with lower lip inserted between teeth

Question

I have noticed the existence of several phones that can be produced with a place of articulation that I haven't seen discussed before. Basically, the two lips contact each other (as in bilabial sounds), and the lower lip is also inserted between the upper and lower teeth. A light force from the bottom teeth holds the lower lip in place.

A few different phones seem possible in this position. The most notable is a high-pitched popping sound which seems like some sort of ejective. To my mind, it is actually much easier to produce loudly and clearly in isolation than the standard bilabial ejective plosive, which sounds slightly different.

You can also produce pulmonic voiced and voiceless plosives and fricatives with the lips in this position. They sound quite similar to the bilabial versions, but I think a large enough difference can be perceived that they could be contrastive in a hypothetical language. You could even make a flapping sound in this position where the lower lip passes by both the teeth and the upper lip, but it sounds the same as a labiodental flap.

Are these sounds phonemic (or common allophones) in any languages? What are they called, and how can they be represented in phonetic transcription?

Answer 1

The teeth cannot exert force, but the mandible can. The teeth could be a point of contact. Various muscles position the lower lip given its attachment to the mandible. Without clear evidence for the actual articulatory dynamics of these segments, we can only guess what these objects are. You should at least provide more information about what language has such sounds, where they occur, more specific that reporting that you have observed several phones.

On the face of it, you are describing a labiodental – a kind of sound that exists in very many languages. [f,v] are the most common of these, and they phonemically contracts with bilabials in a few languages (Gbe, Shona...). Without any information about the phonological system of the language with these purported sounds, there is no specific "appropriate" transcription symbol, so you could write [p, m, f] until you find evidence of a phonological difference.

Your description easily applies to random instances of /p/ in English, but lip-teeth interaction is not a systematic feature of English.

Answer 2

I haven't ever heard of these sounds contrasting with bilabial or labiodental consonants in any natural language (although as a contrast between bilabials and labiodental consonants is itself quite rare, this isn't surprising), and so there's no specific notation in the IPA for them. They could reasonably be transcribed [p͡p̪], [m͡ɱ], [ɸ͡f] etc. (i.e. with the a tie between the bilabial and labiodental consonants of the appropriate manner of articulation).

Any detailed phonetic description should include an explanation of any transcription used rather than just relying on the IPA anyway (as the transcription will generally drop many features that aren't pertinent to that language for ease of reading) so these slightly ad-hoc transcriptions shouldn't cause any particular confusion.

Answer 3

The description comes close to a labiodental affricate that can be found in some Tsonga dialects.