Regarding the horizontal axis, and within the same high, I'd like to know whether back vowels (e.g. /ɤ/) are more sonorous than front ones (e.g. /e/).

  • Do you mean back vowels vs. front vowel, or back round versus front unrounded? Your examples are ambiguous.
    – user6726
    Dec 7, 2017 at 15:15
  • Is roundedness a contrastive feature for sonority as well?
    – GJC
    Dec 7, 2017 at 15:38
  • 2
    Yes, rounding decreases sonority.
    – user6726
    Dec 7, 2017 at 16:25
  • @user6726 O.k., now could you answer the question please? what about the horizontal axis? I know there's an actual trapezoidal scheme, so the scale should be inferred taking that into account
    – GJC
    Dec 7, 2017 at 17:59
  • 2
    This requires some quality time at the library. The only well-established pattern relates to height; we know that backness and roundness can on occasion be relevant, but tracking down the facts is not trivial.
    – user6726
    Dec 7, 2017 at 19:58

3 Answers 3


There is some evidence indicating that back vowels are more sonorous than front vowels, although the relation could also be based on round (more sonorous) vs non-round, since the data comes from Modern Greek where back and round correlate in the typical way. This is discussed in E. Kaisse's Harvard dissertation.

There is a general phenomenon of hiatus resolution whereby V#V sequences reduce to a single vowel by deleting one of the two vowels. Which vowel deletes depends on the properties of the vowels; there is also variation between dialects; there are multiple rules that implement this hiatus-resolution plan; and there are different syntactic conditions on the different rules. The general pattern (most pan-Greek) is that the "more sonorous" vowel is retained, and the hierarchy of vowels, in terms of sonority, is [a > o > u > e > i]. Examples of this here come from Peloponnesian (glosses are my construction based on available information from Kaisse).

/ta éxo/ → [táxo] (I have them); /me aγapái/ → [maγapái] (he loves me); /ta onirévome → [tanirévome] (I dream of them); /to alázo/ → [talázo] (I change it); /to urliazi/ → torliázi] (?he howls it); /tu oðiγó/ → [toðiγó] (I lead to him); /mu éðosa/ → [múðosa] (he gave to me)

Interestingly, the system is rather different in Urban Athenian, which has more specific sandhi processes and a different sonority hierarchy, viz [o > a > u > i > e]. There are other claims regarding sonority-based vowel rules in Greek such as assimilation in Cretan which confirms the general pattern though collapsing /e,i/ into a single position. The interesting thing about the Greek pattern is that it seems to contradict the typical functional explanation for the effect, that more sonorous vowels have a more open vocal tract. Round vowels have a more closed vocal tract. If "scale" effects are always based on sonority, then this calls into question the functional explanation.

The other type of oft-cited evidence regarding sonority is that schwa is often treated differently in stress systems, viz. is skipped for stress. This leads some to say that central vowels are particularly non-sonorous, but that does not address back vs. front.

  • Do you have any link for Kaisse? I didn't find it here
    – b a
    Apr 8, 2018 at 9:22
  • Unfortunately, it's not available through Proquest.
    – user6726
    Apr 8, 2018 at 13:40

Taking into account the theory of distinctive features, all vowels have the same sonority. Since the distinctive features are binary, or is - or is + sonorous.

  • 5
    So you're saying that the notion of a rising vs. falling diphthong is spurious?
    – user6726
    Dec 8, 2017 at 5:01
  • No, it is not a spurious notion, but the difference between raised diphthongs and fallen diphthongs is in the prominence, not in the sonority. So the difference is more suprasegmental than segmental. Dec 11, 2017 at 5:19

Supposing that in English, unstressed vowels are backed, and flaps are more sonorous than unflapped [t], and that flapping of [t] is assimilatory in "petty", etc. vs. no flapping in "petite", then this suggests that back vowels are more sonorous than front vowels.

  • "Potty, booty" indicate the preceding vowel backness does not condition flapping.
    – user6726
    Dec 9, 2017 at 5:12
  • @user6726 True. I suppose it's clear I was referring to the unstressed vowel that follows the flap. I should have mentioned that the flapping of a word-final t before a stressed vowel in the next word ("at Akron", "fat eagle") is a problem unless syllable structure is taken into account.
    – Greg Lee
    Dec 9, 2017 at 14:57
  • "Spitoon" alongside "petite"; "motto" alongside "petty" pose the same problem.
    – user6726
    Dec 9, 2017 at 15:16

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