Even though I don't speak a language with linguolabial consonants, it seems to me that these sounds are easy to produce and also auditorily quite distinct, e.g. the difference between bilabial or alveolar plosives and linguolabial plosives sounds greater (to me) than the difference between voiced and voiceless plosives. So why are they so obscure?

Is it mainly that it's hard for these sounds to evolve from other sounds? I guess it's hard to think of a mechanism whereby another sound would evolve into a linguolabial consonant, except maybe dental fricatives which are already rare.

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    A guess based on nothing concrete at all: the additional extension of the tongue to reach the upper lip is not insignificant. In normal, rapid speech, the tongue would have to move very fast to make it all the way out to the lips and back again in roughly the same amount of time it takes to produce any other consonant. Not impossible, but I would guess a likely place to optimise. Feb 8 at 22:23
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    @JanusBahsJacquet this is my guess too. Seems to me that loss (either shifting to dentals, labials, or a cluster of the two) would be pretty common, and could account for their rarity
    – Tristan
    Feb 9 at 10:50

1 Answer 1


It's for the same reason that English doesn't have true interdentals in everyday speech. Teeth are hard and sharp. Tongues are soft and easily injured. One hard knock to the chin whilst pronouncing the most common consonant in English would result in the loss of the apex of the tongue. Linguolabials are even worse.

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    Most common consonant? If you're referring to /ð/ and /θ/ like I understand you are, they certainly aren't the most common consonants in English (no matter the exact realization).
    – LjL
    Feb 12 at 17:57
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    This hypothesis doesn't pass the sniff test for me. If it were true, those poor, poor Castilians...
    – jogloran
    Feb 12 at 18:19
  • I was under the impression that in AmE the dentals typically were interdental (where in BrE they're typically true dentals). Ofc, for the purposes of this comment I'm ignoring instances where they're either stopped or fronted
    – Tristan
    Feb 13 at 10:09
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    @jogloran likewise, afaict Castilian z (and soft c) is a true dental, not interdental. I agree this doesn't pass the sniff test, but this isn't a good counterargument
    – Tristan
    Feb 13 at 10:11

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