I was wondering why in Japanese, certain consonants change depending on the vowel. For example:

Consonants that do not change:

  • ka / ki / ku / ke / ko
  • na / ni / nu / ne / no

Consonants that do change:

  • sa / shi / su / se / so
  • ta / chi / tsu / te / to

Is there an explanation of this phenomenon? Does it appear in other languages as well?

  • 4
    But they do change! /ki/ and /ni/ (and /hi/) are clearly palatalized/fronted; the Wikipedia article transcribes them as /n̠ʲ/ etc.. Commented May 18, 2012 at 9:36

2 Answers 2


Yes, this is a very common phenomenon - it's called Palatalization. It happens when a consonant is followed by a front vowel (e,i, etc). However:

  • it does not happen to all consonants - depending on the language and its evolution only some consonants may be affected. (as in your example, k does not become ch)

  • it does not happen with all front vowels. In Japanese it's only before i.

This can be found, in various variations, in many languages.

This explains only the change before "i". The explanation for tsu can be found in this article

/t, d, n/ are laminal denti-alveolar (that is, the blade of the tongue contacts the back of the upper teeth and the front part of the alveolar ridge) and /s z/ are laminal alveolar. Before /i/, these sounds are alveolo-palatal ([tɕ (d)ʑ n̠ʲ ɕ (d)ʑ]) and before /u͍/ they are alveolar ([ts (d)z n s (d)z]).

The latter phenomenon is rarer (I can't think of examples other than Japanese). But consonant changes that depend on the preceding or the following vowel are common.

  • 1
    This is not quite accurate. /k/ does in fact palatalize. /s/ and /t/ go even further and turn into a fricative and an affricate, respectively.
    – dainichi
    Commented Jan 30, 2018 at 7:37
  • /k/ does become /ch/ in some Japonic languages. For example Okinawan. Commented Oct 28, 2020 at 10:25

At least some dialects of French also affricate apico-dental stops before i and u. Polish and Brazilian Portuguese affricate and palatalize t and d before i, and Polish palatalizes s in the same environment, distinguishing si from sz (see Schenker 1966).

With regard to Japanese, the phonetic situation is very interesting. The affrication of t and d before all high vowels is the addition of a groove (down the middle of the tongue) articulation instead of a sudden release to the stop. S appears to be unaffected, because it is already articulated with a groove. All three are also palatalized or fronted (articulation shifted to the frontum of the tongue) before the front vowel i.

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