The Japanese little tsu, written “っ” (for example in the word “行った”), represents a pause in the flow of sound when speaking. I’ve heard this mispronounced by beginners, and even by those with several months of experience under their belt, so I thought I would clarify any confusion about how it should be pronounced.
The brief description I just gave about “a pause in the flow of sound” is correct, but doesn’t address the timing of this pause which is where some people go wrong. Japanese syllables are generally spoken in an metronomic, even fashion and this is especially important for the small tsu.
To get the timing right, you can to try to tap a hard surface at an even pace (a sound which could be expressed in Japanese as とんとん), and then try saying 言った（いった), where you pause a full beat on the small tsu in the middle. I’ll try to show this visually below.
い っ た
X X X [Even taps]
During the “っ” your mouth and tongue should be completely still, set in the position for the sound which follows it. In this case, your tongue your be poised on the top of your mouth, ready to say the た sound.
To explain it another way, it’s the pauses relative timing that’s important. For example, for someone who is speaking very quickly the size of the pause will be correspondingly quick, and vice-versa.
If you’re speaking to a native Japanese person, they might understand most of what you are saying even if you don’t time this correctly, but it may require some extra brain power to work out your meaning. The reason for this is there are many words which have the same general pronunciation if you omit the little tsu. To give some examples:
- いった (言った／行った） vs いた （居た）
- きった （切った） vs きた （来た／着た）
- しめった （湿った） vs しめた (占めた／閉めた／絞めた）
- かった (買った／勝った／飼った） vs かた （型／肩）
Japanese already has so many homophones, that omitting the little tsu makes the number of word possibilities to wade through even greater.
There is one situation where the ”っ” is treated slightly different – when put at the end of a word, like in “やめろっ！” Here it adds emphasis by a quick, harsh stop at the end of the word.