How do we tell whether 2 hiragana should fit in 1 "mora" or 2?

For example, why is it that 四季 and 士気 are pronounced as "Shiki" 1 mora, whereas and 指揮 are pronounced as "Shi Ki" 2 morae? N.B. Links bring to a dictionary.

What I meant is that according to the audio files I've linked to in the question, there is a significant difference in the "gap" between the two hiragana.

Why is it that although 式 and 四季 have the same hiragana (しき), 式 has both the clear sounds of "shi" and "ki" (2 distinct "sounds") whereas in 四季 the し and き are slurred to form a single "sound" ?

  • 2
    四季 and 士気 are two morae. By the way, the plural form of mora is morae.
    – user458
    Commented Jul 5, 2011 at 15:25
  • 7
    I think you are a bit confused about the meaning of morae. Pretty much all kana (aside from しょ, しゅ etc.) are exactly one mora. As @William said: you are probably looking at stress or pitch differences. This has already been covered here: japanese.stackexchange.com/questions/646/…
    – Dave
    Commented Jul 5, 2011 at 16:00
  • however according to the audio files i've linked to in the question, there is a significant difference in the "gap" between the two hiragana. For example, 式 has both the clear sounds of "shi" and "ki" whereas in 四季 the sounds are "slurred"
    – Pacerier
    Commented Jul 5, 2011 at 20:19
  • 2
    The question is a little confusing since you seem to be using "hiragana" for a sound rather than for a written symbol. Commented Jul 6, 2011 at 9:15

5 Answers 5


You seem to be confusing morae and syllables. Syllables are units that have a nucleus which is typically either a vowel (which may be both a monophthong or a diphthong) or a sonorant, such as /l/, /m/, /n/ or /r/. The English words "ski" [ski:] and "sick" [sɪk] have just one syllable, while the word button [bʌ·tn] has two, with "n" being the nucleus of the second syllable.

It's important to note that syllables may vary greatly in length, depending on how many consonant they have, whether they are stressed, whether they have a diphthong or a monophthong and whether they have a long, short or elided vowel. The second syllable in "button" ([tn]), for instance, is very short since it is unstressed and it doesn't have any vowel at all, but rather the sonorant "n" that isn't really pronounced for a long time in English (in other languages it may behave differently). Syllables with diphthongs or long vowels, on the other hand are quite longer (this difference is more pronounced in some English accents than in other).

Morae, on the other hand, are quite different from syllable. These are rhythmical units of (relatively) fixed length, and they only count time - not the existence or absence of a nucleus and not even the existence of sound (the Japanese small tsu, っ, may count as a mora even in the cases where it ends up being just a silent pause). You can imagine a mora as the beat of an inaudible metronome that goes inside the speaker's head and represents the tempo of his or her speech: when you speak very fast, a single mora may take as little as a tenth of a second, and when you dictate something in an exaggerated manner it can take as much as two seconds.

Since mora is entirely a unit of length and not a standard structure for how phonemes may be joined together, you can see that long vowels and geminated (doubled) consonants take two morae, and the consonant 'n', when it comes without a vowel, takes a whole mora for itself. This means that even when there's a muted vowel (such as the /i/ in 士気), the consonant still takes an entire mora on its own. I believe that if you'd count the length of the audio samples on WWWJDIC you'll notice that they actually have roughly the same length (despite some of them having a muted vowel and some of them not).

What confused you, of course, was interpreting the Japanese examples as the English syllables you've heard and trying to count morae according that. But just as the concept of mora is not really useful for understanding when applied to English (at least when it is not sung or solemnly recited), the concept of syllable is quite alien to Japanese. You can divide Japanese to syllables if you want, but then you'd be dividing it by English (or German or Chinese or whatever) standards. Japanese phonology per se (and I'm not talking about unprovable universal phonology models here) has no internal concept of a syllable. Only the morae count.

  • Your answer is correct in pointing out the differences between morae and syllables, but I don't agree with your last paragraph. There is a relatively simple mapping between them, as can be seen in your answer, and syllable, as well as mora, play some role in Japanese phonology. There is a Japanese standard for dividing into syllables. Probably syllables are important for any natural langugage. Morae for some.
    – user458
    Commented Jul 7, 2011 at 20:30

I think that's still 2 mora. The only time multiple kana will be a single mora is when the second one is smaller, like しゃ (sha) and きょ (kyo).

I think your real questions is about the difference in stresses, and I think you just have to learn by experience for that.

The little つ is an exception to this 'rule', as sawa pointed out below. (I wasn't aware of this.)

  • 7
    You should be more cleaer about 'when the second one is smaller'. As you correctly point out, glides (expressed by , , ) are not counted as individual morae. But gemination (expressed by ) is counted as one mora.
    – user458
    Commented Jul 5, 2011 at 16:00

I think you are confusing the morae count with syllables with silenced vowel. In spoken Japanese, there are some syllables, for example く し す etc, that are pronounced with silent vowel in some particular conditions. For example, in はじめまして the し is pronounced as 'sh' with the 'i' silenced, as in "ha-ji-me-ma-sh-te".

On top of that, there is also pitch accent. Different words that are formed by the exact same syllable sequences may be pronounced with different pitch accent; the famous example being はし for chopsticks vs bridge.

This is purely my hypothesis, but I think pitch accent is one of the conditions for the silenced vowel syllables to be silenced. Here is sort of prove: open this particular website. Plug in your headphones. Then try comparing three accents for はしが (edge, chopstick and bridge). You'll notice that the し for chopstick is vowel-silenced ("ha-sh-ga"). Now trace through that second column and try listening to あきが (autumn) and かきが (oyster), and compare them with their other accents. You'll notice that the き in 'autumn' and 'oyster' is also vowel-silenced. So I think that pitch accent does influence whether the vowel is silenced or not.

Back to your しき, here are the pitch accents that I hear:

四季 : LL : sh-ki
士気 : LL : sh-ki
式 : HL : shi-ki
指揮 : HL : shi-ki

  • heys yea i guessed i had it confused with silent vowel there.. >.<
    – Pacerier
    Commented Jul 8, 2011 at 7:02

First, you probably misunderstood the meaning of "mora". Morae are essentially syllables, except that ん and double consonants also constitute morae.

Second, I think you were mislead by the different pronunciations on the website. They should sound exactly the same -- or, to be precise, all the pronunciations you hear can represent all of the words you mention.

Pitch is not an issue here as all these words have the same pitch, namely HL. (You can confirm the pitch in the dictionary page for しき.


The recordings for the words you linked were made at different times. They are not different for phonological reasons, but simply because they were made separately -- in other words, they are interchangeable, and there is no distinctive feature that you are missing out on.

Test it out on a native speaker and see if they can correctly and consistently identify the 3 different recordings as the header words. They won't.

Otherwise, as others have pointed out, both words (or realizations) are 2 morae (or syllables). The fact that the first vowel is more or less voiceless is irrelevant. Pitch is also the same in the recordings and is irrelevant here.

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