I have a human culture that gradually develops an underwater civilisation. They still require mouth and nose breathing and will be living in air bubbles, retaining traditional phones. They do spend a lot of time swimming around and I want them to be able to communicate through water as well. Modified and new underwater phones will develop over time etc.

What I'm interested in and haven't been able to find an answer to is, of our current available phones, which ones can be made, heard and understood underwater?

  • let's work off the idea that there is no breathing equipment in the way of these vocalisations. Free diving.

Before I start constructing modified sounds and augmentations etc I would like to know what I can keep of our current soundbank. What do I have to throw out completely. I may ask a later question on constructing/modifying new sounds for underwater languages.

  • I understand that humans hearing underwater is affected by bone conduction, skipping the first 2 ear bones. We will be able to hear much higher frequencies and from further away, although direction will be hard to discern. I'm still reading up on all of these features but just wanted to say I was aware of these various facts. For the purpose of this question, I'm just focused on using current known sounds underwater.
  • I am aware of this answer on wb.se. Commented Jul 12, 2018 at 10:01
  • "IPA phones" are not a thing. The IPA is a writing system for phones; the IPA did not bring any phones into existence.
    – ubadub
    Commented Oct 2, 2018 at 21:21
  • Also, if they spend a lot of time swimming around while holding in air, why would they want to talk? It would dramatically waste the amount of breath they have.
    – ubadub
    Commented Oct 2, 2018 at 21:23

2 Answers 2


From reading the answers to the Worldbuilding SE you reference, I would draw the following conclusions:

  1. anything unvoiced goes out of the window. So no /f/, /p/, /k/, /t/, /s/ etc. They are pretty useless, as they are predominantly in the higher frequency ranges (especially the fricatives) or very short and without much energy (which would be provided by the glottis). And higher frequency sounds travel less well in water.

  2. consonants in general are either short (plosives) or prefer higher frequency bands (fricatives), so apart from /r/ and /l/ (and possibly /v/, /z/) would not carry well underwater.

  3. vowels seem best suited. And looking at the frequency characteristics, those with lower formants seem slightly preferable, so /u/ and /o/, and the back /a/: vowels produced at the back of the vocal tract. The fronted vowels (/i/, /e/, frontal /a/) would have a higher frequency component again.

So in summary I would think a vowel-based phoneme inventory might be best. This inventory could be supplemented by some approximants (/l/, /r/, /j/, and /w/). Which is weird, as consonants usually carry most information in natural language!


  • Whch s wrd, s cnsnnts sll crr mst nfrmtn n ntrl lngg!
  • i i ei, a ooa uuay ay o ioaio i aua auae!
  • 1
    What about clicks and affricates etc? Might not be able to tell them apart but could still make use them of them in general...if they work underwater that is. Commented Jul 12, 2018 at 11:32
  • 3
    @EveryBitHelps Clicks might work. I have to admit my answer is rather Euro-centric in the phoneme inventory it presupposes. Affricates have the fricative frequency issue again, though /d͡ʒ/ might be feasible as it's voiced. Commented Jul 12, 2018 at 13:00
  • 2
    @EveryBitHelps In natlangs, clicks are produced by sucking in air with your tongue, rarefying it between two points of closure, then releasing the front point of closure to make the click sound. Given the acoustics involved, I'm thus not sure it's even possible to makes clicks underwater unless you're, like, a dolphin or something.
    – Sparksbet
    Commented Jul 12, 2018 at 21:45
  • @Sparksbet I was sort of imagining a dolphinese end result :D Good to know about the clicks. Will work on it when creating news sounds. Commented Jul 12, 2018 at 21:50
  • 1
    It is possible to make some clicks with purely internal air movement, not requiring any ingress of air through the mouth--and indeed even with the mouth closed. This is easier with clicks articulated further back, so you might get by with palatal and velar clicks (produced by using the tongue to rarify air in the front of the mouth, compressing it in the back, and then releasing a closure), and glottal pseudo-clicks (ingressive glottal stops) which rely on decreasing lung pressure compared to the oral cavity. Commented Jul 12, 2018 at 22:56

A while ago, someone on reddit tried to test this experimentally (using a bathtub). Here’s what they found:


Overall, these were the hardest to distinguish (at least personally). The most striking vowels were /æ, i, u/. /a, o, ɑ, ɒ, ɔ/ all seemed to blend together, losing distinction. The same happened to close-mid and open-mid center vowels as they too blurred. The front close vowels also blurred, as did the back close and close-mid vowels.

Tone definitely helped to distinguish sounds, and you can really play with vowel length. It's eerie to hear your voice carry underwater and not dissipate as quickly. You can also factor in uvular trilled vowels. With tone these sound very unique.


I found it most easy to distinguish /p, t, k/ from their ejective counterparts, but not voiced /b, d, k/. Like the vowels, most of the fricatives (labial, dental, and alveolar) blurred together. You can distinguish this amorphous group against /ts'/. Retroflex fricatives merged with /tʃ/ and /dʒ/. As you farther back the consonants begin to get indistinguishable from vowels. The other consonants followed suit, at least to my ears. Nasals were all identical. Clicks were not possible, unless you want to inhale and choke on water.

reddit post

Now of course this isn’t exactly hard science, as it’s all based on the perception and articulatory skill of one person. Still, it provides intersting data.

  • This is excellent. Thanks for sharing. I am curious about a two person experiment. As this person knew what sounds they were making, they may have a slight bias on what is actually understandable. Obviously you can't fit two people in a bath...underwater at least...but would be interesting if two people could recreate this experiment in a swimming pool etc. Find out what the second person can actually hear and understand. Commented Jul 13, 2018 at 20:33

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