I am writing a species of humanoid whose skull shape more resembles that of young baboons, with somewhat large canine teeth. They are fellow primates and have a similar upright posture to humans, maybe with a slightly greater degree of lordosis. The two species have been in regular contact since prehistory.

(There's some weird stuff going on with their evolution being tampered with by an external force through genetic modification, but that's not necessarily related. As far as this question is concerned, that external force is the writer ;))

I would like them to be capable of human speech. Their articulation does not have to be identical to the average human, and can be somewhat distinctive for certain phonemes. However, they should be capable of realizing all the phonemic contrasts that a human could, in a way that can be heard by human ears.

For example, an individual adopted as an infant by humans would acquire a human mother tongue as easily as their adoptive siblings, and adults are as capable of learning to speak an additional, human language as we humans are.

This is a fictional species, so I'm free to make their lips more flexible than real life nonhuman animals, or to specify the shape of their tongue, nasal cavity, larynx etc. I would like to keep their snoutedness and fangedness, and would like to stay close to the general concept of mammalian vocal folds and human articulatory phonetics. With those constraints, how plausible is human-like speech in such a species? What are the hard limits for human-like speech in such a species?

Edit: I would like to stick closely to the human/mammalian way of making speech sounds (ie. tongue at places of articulation, consonants are through partial or complete closure of the vocal tract, vowels are sounds without any closing of the vocal tract) so I'm excluding syrinxes and the like. There is often talk of how nonhuman species could not make certain sounds (ie. labial sounds like p b f v), and I'm trying to figure out what specific anatomical traits to include/avoid in the design as i feel like my sketches and imagination make them too "dog-like".

  • 2
    $\begingroup$ "What are the hard limits for human-like speech in such a species?" What makes you believe that there are any hard limits for human-like speech in such a species? Baboons have all the necessary pieces -- a voice box, vocal chords, a pharynx, a free and flexible tongue, and free, fleshy and flexible lips. Yes, it would be quite unlikely that their phonatory apparatus is made just right to make human sounds, but there is absolutely not impossible and stranger things have happened. After all, parrots and loudspeakers can make all human sounds, and their anatomy is vastly different. $\endgroup$
    – AlexP
    Commented Jan 25 at 21:17
  • $\begingroup$ (In other words, I do not see what is the difficulty. Maybe you could edit the question to highlight what is the actual perceived problem.) $\endgroup$
    – AlexP
    Commented Jan 25 at 21:22
  • $\begingroup$ Also, there is a lot of wiggle room as far as human speech perception. Maybe it doesn't sound quite like a native speaker, but it's likely good enough. $\endgroup$ Commented Jan 25 at 21:25
  • $\begingroup$ I agree with @SoronelHaetir : the common, terrestrial example would be birds. They have a completely different biological apparatus for producing sounds (beak instead of mouth, syrinx instead of pharynx), and yet there are species of birds able to replicate human speech sounds more than well enough for us to understand words and phrases. Given a more similar biology, it seems like your species should be able to replicate human speech sounds well enough to be understood. It's unlikely they'd sound exactly like a human, but for us to understand them that doesn't seem to matter. $\endgroup$ Commented Jan 25 at 21:29
  • 1
    $\begingroup$ @realityChemist You mean the way many ventriloquist substitute a g for a b I'm guessing? any animal with a dog like muzzle and decent tongue mobility but no fine control of the lips should be able to replicate that at least, and will be perfectly understandable to most listeners, yep. $\endgroup$
    – Pelinore
    Commented Jan 27 at 21:03

2 Answers 2


I don't think there are any hard limits.

To start with the vowels, all you need is vocal cords, vibrating at a fixed frequency, and a tongue flexible enough to get the oral cavity into a shape with given two or three lowest resonance frequencies (formants). Of course, the easiest is to give your creatures the oral cavity of the same shape as humans, but this is not really necessary. E.g., if it is longer and narrower, they can reproduce the human shape in the rear part and make the rest just a narrow tube that conducts the sound - this would be similar to you speaking into a short piece of tube attached to your mouth. But this is not really necessary, as there are many different cavity shapes that achieve three given lowest frequencies, meaning that the same vowel can, theoretically, result from very different cavity shapes and tongue positions. The creatures with smaller cavity will talk in higher pitch, though.

For consonants, the basic physics is obstructing the airflow and then releasing it through an opening of a required shape between your lips, tongue, or teeth. Again, all you seem to need is a tong and lips flexible enough. As for the teeth shape, I don't think it matters much - human teeth are quite variable, and even if a person is missing a few, they may speak funny but we understand them :)

  • 3
    $\begingroup$ "With the vowels, you need vocal cords": Only for voiced vowels. And you also need vocal chords for voiced consonants such as /b/, /d/, /g/, /l/, /m/, /n/, /r/, /v/ and /z/. Yes, in English all the vowels are voiced in normal speech, but I suppose that even native English speakers can whisper -- and when whispering all vowels and consonants are realized as unvoiced. $\endgroup$
    – AlexP
    Commented Jan 25 at 21:53
  • $\begingroup$ "a required shape between your lips, tongue, or teeth" Birds (parrots and crows etc) manage it without any flexibility in the lips, they have this thing called a syrinx between the windpipe and the lungs. $\endgroup$
    – Pelinore
    Commented Jan 26 at 3:23

A little bit of a frame challenge here

I know you want to stick closely to the human way of making sounds but you really don't have to.

You don't need everything we have.

Crows and parrots are able to mimic human speech perfectly or near perfectly enough to most peoples ears for any reasonable purpose, and their face morphology is nothing like human, they rely on what's called a syrinx, an organ that sits between the windpipe and the lungs where no one can see it, so go wild, it doesn't matter what your species faces looks like or if they even have lips, you can bury all the necessary organs to replicate speech to any quality you want elsewhere in their body.

You don't even need anything we have.

A syrinx works much like an electric speaker anyway, so if you want you can just say they've a membrane anywhere on or in their body you like that they can vibrate to produce any sound you need them to like an electric speaker.

So don't sweat it too much, let them look however you want or need them to, give them any bits we have you want or are comfortable with that fits the appearance you want and just adjust the sounds they can make substituting other sounds in the same way a ventriloquist does for those sounds they can't make to give odd but understandable speech, and if it really is important to you that they sound perfectly normal but also want them to have features that might suggest otherwise just say they have a syrinx or speaker membrane in their throats somewhere.


"A syrinx works much like an electric speaker anyway" .. in as much as it's vibration that generates the sounds that is.

Syrinx (bird anatomy) - Wikipedia

sound is produced by vibrations of some or all of the membrana tympaniformis .. and the pessulus, caused by air flowing through the syrinx

Which isn't really all that different from our vocal chords I suppose (being also vibration) but the range of sounds is obviously a lot greater than our vocal chords can produce.

Bird Vocalizations - Montana Science Partnership

By contrast, the syrinx – the vocal organ of a bird – is a unique bony structure surrounded by an air sac which lies at the lower end of the trachea. Unlike the larynx, a bird's syrinx contains no vocal chords. Instead, sound is produced in this organ through the vibration of the walls of the organ.

  • 1
    $\begingroup$ If you give them both, a syrinx and vocal chords, they'll be able to harmonize with themselves ;) .. though trying to explain why natural selection would have given them either if they'd already developed the other may be stretching it a bit ;) $\endgroup$
    – Pelinore
    Commented Jan 27 at 20:45

You must log in to answer this question.