Definition:
The small tsu (っ in hiragana, ッ in katakana), formally called sokuon (促音, literally “choked sound”), represents a geminate consonant — a doubled or lengthened consonant that creates a brief glottal closure or held stop before the following consonant. It is written as a smaller version of the regular tsu (つ/ツ) and occupies one mora in Japanese timing.
In-Depth Explanation
How it works:
The small tsu doubles the consonant that follows it. In phonetic terms, you hold the mouth in position for the next consonant for one extra beat (mora) before releasing:
| Without っ | With っ | Meaning difference |
|---|---|---|
| きて (kite) [2 mora] | きって (kitte) [3 mora] | come / stamp |
| かた (kata) [2 mora] | かった (katta) [3 mora] | shoulder / won |
| いた (ita) [2 mora] | いった (itta) [3 mora] | was / said |
| さか (saka) [2 mora] | さっか (sakka) [3 mora] | slope / author |
Mora timing:
Japanese is a mora-timed language. The small tsu counts as one full mora — it takes the same amount of time as any other kana. This is critical for correct pronunciation and is one of the hardest timing distinctions for English speakers, who are accustomed to stress-timing rather than mora-timing.
Which consonants can be geminated:
| Consonant | Example | Romanization |
|---|---|---|
| /k/ | がっこう | gakkou (school) |
| /s/ | ざっし | zasshi (magazine) |
| /t/ | きって | kitte (stamp) |
| /p/ | いっぱい | ippai (full) |
| /ch/ | マッチ | matchi (match) |
| /sh/ | いっしょ | issho (together) |
Generally, the small tsu appears before voiceless consonants (/k/, /s/, /t/, /p/) and their affricates. It does not typically appear before voiced consonants (/g/, /z/, /d/, /b/) in native Japanese words, though it can in loanwords (e.g., ベッド, beddo, bed).
In katakana (loanwords):
Katakana uses ッ heavily to represent English geminate and final consonants:
- カップ (kappu, cup)
- ロック (rokku, rock)
- ネット (netto, net)
- バッグ (baggu, bag) — geminate before voiced consonant, only in loanwords
Common learner mistakes:
- Skipping the pause entirely (saying “kite” for “kitte”)
- Making the pause too long (sounds like a hesitation rather than a held consonant)
- Failing to hear the difference in listening (a critical distinction for comprehension)
Related Terms
See Also
Research
- Vance, T. J. (2008). The Sounds of Japanese. Cambridge University Press. — Detailed acoustic and articulatory description of geminate consonants in Japanese.
- Han, M. S. (1994). Acoustic manifestations of mora timing in Japanese. Journal of the Acoustical Society of America, 96(1), 73–82. — Empirical study of mora timing including sokuon duration.