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The short answer
Aizuchi (相槌) are the small words and sounds a listener uses while someone else is talking: うん, へえ, そうなんだ, なるほど and so on. They don’t answer anything. They tell the speaker “I’m here, I’m following, keep going.”
English speakers use these too, with “uh-huh,” “right” and “really?” The difference is how much they matter. In Japanese conversation, a listener who stays quiet while someone talks can easily come across as not listening, not interested, or even a little annoyed. Many Japanese speakers expect to hear small signals throughout the conversation, and when the signals stop, they tend to slow down or check whether you’re still with them.
As a native Japanese speaker, I’d put it this way: in Japanese, listening is something you do out loud. The good news is that a handful of aizuchi cover most situations, and they’re easy to start using right away. This guide walks through the common ones, when to use the casual or polite version, how often to use them, and the mistakes learners most often make.
The core aizuchi
These are the ones you’ll hear constantly. Each one does a slightly different job, so it helps to learn what it signals, not just what it translates to.
- うん / はい / ええ (un / hai / ee). The most basic “I’m following.” うん is casual, はい is polite, and ええ is polite with a slightly softer, more conversational feel. All three usually mean “go on,” not “yes, I agree.”
- へえ (hee). “Oh, really?” or “huh, interesting.” It reacts to something new or mildly surprising. A longer, rising へえー sounds more impressed.
- そうなんだ / そうなんですか / そうなんですね (sou nan da / sou nan desu ka / sou nan desu ne). “Oh, I see” or “is that so?” It shows you’ve taken in new information. そうなんだ is casual. Of the polite forms, そうなんですね sounds calm and accepting, while そうなんですか sounds a little more surprised.
- なるほど (naruhodo). “I see” or “that makes sense,” used when something has been explained and it clicks. It’s common among friends and peers. The polite-setting caution is covered in the mistakes section below.
- たしかに (tashika ni). “That’s true” or “good point.” You use it when you agree after thinking about what was said, not as a reflex.
- ほんと？ / 本当ですか (honto? / hontou desu ka). “Really?” It invites the speaker to say more. Said with a bright tone, it shows interest. Said flatly, it can sound like doubt, so tone matters.
- うそ！ (uso!). Literally “a lie!”, but used as “no way!” in reaction to surprising news. It doesn’t accuse anyone of lying. It’s casual, so keep it for friends.
- すごい / すごいですね (sugoi / sugoi desu ne). “Wow” or “that’s amazing.” Useful when someone shares good news or something they did.
- そうそう (sou sou). “Right, right, exactly.” A quick, warm agreement, often when the speaker says something you were about to say yourself.
- だよね / ですよね (da yo ne / desu yo ne). “I know, right?” It agrees and adds a sense of shared feeling. だよね is casual, and ですよね is its polite version.
- あー / ああ (aa). A drawn-out “ah” of recognition, as in “ah, that place” or “ah, I get it now.” It’s often combined with others, as in あー、なるほど.
You don’t need all of these at once. Most learners do well starting with three: うん or はい for “I’m following,” へえ for surprise, and そうなんだ or そうなんですね for new information. Those alone make you sound far more engaged. Several of these reactions also appear in Natural Japanese Phrases Textbooks Don’t Teach, alongside other everyday phrases.
Casual or polite: a quick guide
Aizuchi follow the same rule as the rest of Japanese: match the relationship. Here’s a rough guide. Workplaces and individuals vary, so treat it as a starting point rather than a rulebook.
| Meaning | Friends | Coworkers and peers | Seniors, teachers, customers |
|---|---|---|---|
| I’m following | うん | うん / はい | はい / ええ |
| Oh, I see (new information) | そうなんだ | そうなんだ / そうなんですね | そうなんですね / そうなんですか |
| That makes sense | なるほど | なるほど / たしかに | そうなんですね / おっしゃる通りです |
| Really? | ほんと？ / うそ！ | ほんと？ / 本当ですか | 本当ですか |
| Wow | すごい | すごい / すごいですね | すごいですね |
| Exactly | そうそう / だよね | そうですね / ですよね | そうですね |
おっしゃる通りです (ossharu toori desu), “it’s just as you say,” is respectful language, and it’s most common at work. If you’re still getting used to that level of politeness, Keigo for Beginners explains how respectful forms work. For most everyday polite conversations, はい and そうなんですね are enough.
Timing and frequency
Aizuchi usually come at natural breaks in what the speaker is saying: the end of a phrase, a short pause, or a point where the sentence could end. You don’t wait for the speaker to finish a whole story. In Japanese, long stories are often told in small pieces, with the speaker leaving a tiny gap after each one for the listener to fill.
A common pattern looks like this:
- A: 昨日、駅で (kinou, eki de) — “Yesterday, at the station…”
- B: うん (un)
- A: 高校の友達に会って (koukou no tomodachi ni atte) — “I ran into a friend from high school…”
- B: へえ (hee)
- A: 十年ぶりだったの (juunen buri datta no) — “It was the first time in ten years.”
- B: えー、すごい！ (ee, sugoi!) — “Wow, really!”
To many English speakers, this can feel like a lot of interrupting. Japanese listeners tend to hear it as attentive, not rude. Aizuchi are short and don’t take the turn away from the speaker, so they sit alongside the talking rather than cutting across it.
Phone calls need even more of them. Without facial expressions or nodding, your voice is the only signal the other person gets, so a silent listener on the phone can quickly make a Japanese speaker ask もしもし？ (“hello? are you there?”). If you notice that happening, you’re probably not using enough.
Frequency is a feel you build, not a number to hit. A useful guide is to match the speaker: when they’re telling a lively story, respond often and with more energy, and when they’re explaining something carefully, use quieter はい and うん.
Common mistakes learners make
Treating はい as “yes, I agree.” This is the big one. In aizuchi, はい, ええ and うん usually mean “I’m listening,” not “I agree.” A Japanese colleague who says はい several times while you explain your plan may not have agreed to anything yet. The same goes the other way: if you say はい while someone explains a request, they may take it only as a sign that you’re following. If you need to show agreement, say it separately, for example わかりました (“understood”) or いいと思います (“I think that’s good”).
Using なるほど with seniors. なるほど is natural with friends and peers. With a boss, a teacher or a customer, some people feel it sounds a little like you’re evaluating what they said, as if you’re judging whether it makes sense. Not everyone feels this way, and you’ll hear it at work all the time, but it’s safer to use そうなんですね, or おっしゃる通りです when you want to show strong agreement.
Too few aizuchi. Staying quiet to be polite, the way you might in some cultures, can come across as cold or distracted in Japanese. If a speaker keeps checking with you (…ね？ or わかる？), they may be looking for more signals.
The same one over and over. Repeating うん、うん、うん in exactly the same flat tone can sound mechanical, or like you’re waiting for the speaker to finish. Mix a few different ones, and change your tone to match the content.
A fast, repeated はいはい. Said quickly, はいはい can sound impatient, like “yeah, yeah, I get it.” Many people hear it as dismissive, so keep はい slow and single with anyone you don’t know well.
Aizuchi in the wrong register. うそ！ or まじで？ (maji de?, “seriously?”) to a senior colleague may sound too casual. When in doubt, the polite versions are the safe default.
Nodding: the silent aizuchi
Aizuchi aren’t only sounds. Nodding does the same job, and in face-to-face conversation, Japanese listeners often nod along with the voice, or nod alone during quieter moments. A small, repeated nod says “I’m following,” much like うん.
Like spoken aizuchi, nods tend to come at the breaks in the speaker’s sentences. In meetings or formal settings, you’ll often see quiet nodding without much sound, because frequent voiced aizuchi can feel too casual there. In video calls, nodding matters more than you might expect: with audio lag, spoken aizuchi can overlap the speaker, so a visible nod is often the smoother signal.
Nodding doesn’t mean agreement either. As with はい, it usually means “I’m listening.” If you’re a learner who nods to be polite while not really following, it’s worth saying so. ちょっとわからなかったんですが… (“I didn’t quite catch that…”) is much better than nodding through something important.
How to practice
Aizuchi are hard to learn from a list, because so much depends on tone and timing. A few ways to pick them up:
- Listen for them on purpose. Watch a Japanese drama, a variety show or a conversational podcast, and pay attention only to the listener for a few minutes. Notice which aizuchi they use, how often, and how the tone changes.
- Shadow the listener, not the speaker. Pause after a stretch of conversation and repeat the listener’s aizuchi with the same timing and tone. It feels strange at first, but it trains the rhythm.
- Use them in text too. Many aizuchi carry into messaging, often in shortened forms. How to Text in Japanese (LINE) covers how reactions like these work in chats.
- Get feedback from a live speaker. This is where a conversation lesson helps most. Ask your tutor to point out when you go quiet, when you repeat the same aizuchi, and when your choice doesn’t fit the politeness level.
For live practice, italki lets you book individual lessons with no subscription, which works well if you want a session or two focused just on listening reactions. Preply uses tutor-specific subscriptions that renew every 28 days, starting with a paid trial lesson, which suits you better if you want the same tutor to track your habits over time. A simple exercise: ask the tutor to tell you a story for five minutes while you respond only with aizuchi, then ask for feedback. Best Online Japanese Tutors compares the options in more detail.
FAQ
Is it rude not to use aizuchi?
It isn’t rude in a formal sense, but it can make you seem uninterested or distracted, and many speakers will slow down or check whether you’re following. Using a few, even simple ones like はい and そうなんですね, usually makes conversations noticeably smoother.
Does はい always mean yes?
No. As an aizuchi, はい usually means “I’m listening.” When someone asks you a direct question, はい can mean “yes,” but during someone else’s explanation, it’s usually just a signal to keep going. If you want to show agreement clearly, add words that say so.
Can I use なるほど with my boss?
Many people do, and it isn’t a serious mistake. Some people feel it sounds slightly evaluating when said to a senior, so そうなんですね is the safer choice in polite settings.
How many aizuchi should I use?
There’s no set number. Match the speaker’s energy and the setting: more in a lively chat or on the phone, fewer and quieter in formal meetings. If the other person keeps checking whether you’re following, you probably need more.
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