| Full-sized | Sokuon | |
|---|---|---|
| Hiragana | | つ | | っ |
| Katakana | | ツ | | ッ |
The sokuon is used for various purposes. One is for showing a geminate (doubled) consonant, which is represented in rōmaji by the a double consonant such as the double t in hatto. This is not a glottal stop.
Examples:
The sokuon is also used at the end of a sentence, to indicate a glottal stop (a sharp or cut-off articulation), which may indicate angry or surprised speech.
In order to enter the sokuon using a computer or word-processor, there are several methods, such as xtu, ltu, ltsu, etc.
In the International Phonetic Alphabet, the sokuon sound is marked either with a colon-like mark or a doubled consonant:
In historical kana usage, the sokuon was often represented by a full-sized tsu kana rather than a small one. In all forms of romanization the sokuon is represented by the doubling of the following consonant, with the exception of the c in chi in the Hepburn system, where the sokuon is represented by a "t". Thus the Japanese tea matcha (抹茶) is written in kana as まっちゃ but in Hepburn romanization as matcha. The Nippon-shiki and Kunrei-shiki systems both represent this as mattya, thus avoiding the problem.
Sometimes you see a small tsu (known as a sokuon) at the end of a sentence. This small tsu indicates a `glottal stop'. This means you use your epiglottis (the little flap that closes the pathway to your throat when you swallow) to stop the flow of air. The small tsu indicates a verbal `exclamation mark'. When a sentence ends abruptly, as in だまれっ (damare!, shut up!), it might be followed by a small tsu.
This `abrupt ending' sound is completely different from the sound of small tsu coming before another consonant, such as `s'.
In order to represent the sentence-ending sokuon in romanized Japanese, the fourth edition of Kenkyusha's New Japanese-English Dictionary used a semicircular mark above the final vowel, ǎ.
On a computer input system, the sokuon on its own can be input either by typing a doubled consonant such as kku (っく) and deleting the final character, or by typing "xtu". See waapuro rōmaji.