Japanese Long Vowels: Why おばさん and おばあさん Sound Different

Japanese vowel length can change the word you are saying. The key beginner skill is simple: when a vowel is long, hold it for roughly twice as long as a short vowel instead of treating the extra kana as a new, separate sound.

Here is the pair that shows why. The only difference is one extra あ (a), and it changes the person you are talking about:

The extra あ (a) matters. If you rush through it, two different words can sound too similar.

Start with a difference you can hear

Say the two words slowly, then break them into beats, called mora in Japanese rhythm. Each written kana takes one beat, including ん (n): お・ば・さ・ん (o-ba-sa-n) has four beats, and お・ば・あ・さ・ん (o-ba-a-sa-n) has five.

In おばあさん (obaasan), do not turn ばあ (baa) into two sharply separated sounds. Keep the あ (a) sound going longer, so ばあ (baa) is “baa” with a longer a sound. That extra length is part of the word.

Short and long vowels

Japanese has five basic vowel sounds. The English comparisons below are approximate; keep each Japanese vowel steady:

• あ (a): like the “a” in “father.”
• い (i): like the “ee” in “see,” but shorter when it is not lengthened.
• う (u): a short “oo”-like sound, usually made without strongly rounding the lips.
• え (e): like the “e” in “bed,” but kept steady.
• お (o): like an “o” sound kept steady rather than turning into an English-style “oh.”

Any of these vowels can be lengthened. The aunt and grandmother pair lengthens あ; the uncle and grandfather pair does the same with い:

The difference is not about saying the long vowel louder. It is about giving it more time.

Why vowel length matters

English speakers often listen mainly for which vowel they hear. In Japanese, you also need to notice how long the vowel lasts.

Listen to the uncle and grandfather pair again. The いい (ii) in おじいさん (ojiisan) lasts longer than the い (i) in おじさん (ojisan):

Another useful pair contrasts ここ (koko, here) with こうこう (koukou, high school):

These are different words, and the long お (o) sounds in こうこう (koukou) help distinguish them.

Vowel length is part of recognising and producing the word correctly.

What you see and what you say

Long vowels are not always written by simply repeating the same hiragana. If the scripts are new to you, the guide to hiragana, katakana and kanji explains how they work together.

Long あ

You may see あ (a) after another あ (a) sound. The あ (a) sound in ばあ (baa) is then held longer:

Long い

You may see い (i) after another い (i) sound, and the いい (ii) is held longer:

Long お

A long お (o) sound is often written with う (u):

In words like this, the う (u) is not normally pronounced as a separate English-style “oo.” It helps make the preceding お (o) sound longer.

So avoid saying こう (kou) as “ko-oo.” Aim for one sustained vowel: こう (kou), a longer “ko.”

There are also words where a long お (o) sound is written with お (o), so learning the spelling together with the word is safer than guessing.

Katakana uses a visible long-vowel mark

Katakana makes many long vowels easier to spot because it often uses ー. Each of these words has at least one:

In コーヒー (koohii), both ー marks lengthen the vowel before them. Break it down into コー (koo) and ヒー (hii), then put the two halves together:

Do not ignore ー when reading aloud.

Listen for time, not extra stress

English often uses stress to make one part of a word stand out. That can tempt beginners to pronounce a long Japanese vowel by making it stronger.

Instead of making the vowel louder, give it more time.

Compare the aunt and grandmother pair once more, tapping once for each beat. お・ば・さ・ん (o-ba-sa-n) takes four taps; お・ば・あ・さ・ん (o-ba-a-sa-n) takes five, because the second word gets an extra beat for あ (a):

Now try お・じ・さ・ん (o-ji-sa-n) and お・じ・い・さ・ん (o-ji-i-sa-n). The extra time belongs inside the word.

Useful examples to read aloud

The requests below use をください (o kudasai, please give me). The last example uses いきます (ikimasu), the polite form of “go.” Keep your attention on the long vowels as you say each sentence.

Start with the four family words. Listen for the short あ (a) in ば (ba), then the longer あ (a) in ばあ (baa):

Then the short い (i) in じ (ji), and the longer い (i) in じい (jii):

In こうこう, both お (o) sounds are lengthened:

In the requests, listen for a long お (o) in コー (koo) and a long い (i) in ヒー (hii), then the long え (e) shown by ー in ケーキ:

1. コーヒーをくださいKoohii o kudasai.Coffee, please.
2. ケーキをくださいKeeki o kudasai.Cake, please.

Finally, listen for the long う (u) and long あ (a) in スーパー (suupaa):

A realistic listening trap

Imagine someone says this:

If you hear おばさんです (obasan desu), you have lost the extra あ (a). You may know both words perfectly on paper and still miss the extra time given to the vowel in speech.

Train the contrast as a pair: おばさん (obasan) and おばあさん (obaasan), then おじさん (ojisan) and おじいさん (ojiisan). Learning contrasting words together makes the length difference easier to notice.

Common pronunciation mistakes

Treating the extra vowel as optional

The mistake is pronouncing おばあさん (obaasan) like おばさん (obasan). Keep the longer vowel, because the extra あ (a) changes the word:

Separating a long vowel too strongly

Avoid turning こう (kou) into two strongly separated sounds such as “ko-oo.” In this kind of word, aim for one longer お (o) sound.

Making a long vowel louder instead of longer

The goal is not BA! with extra force. The goal is ばあ (baa) with more time on the vowel.

Ignoring ー in katakana

Do not read コーヒー (koohii) as if it were コヒ (kohi). The ー marks are part of the pronunciation.

Read-aloud practice

For a listening model, try the Japan Foundation’s katakana long-vowel examples with the Lesson 2 audio. Then return to the contrasts below.

First, say each pair slowly. Make the long version clearly longer:

Now tap the rhythm while speaking: お・ば・さ・ん (o-ba-sa-n), お・ば・あ・さ・ん (o-ba-a-sa-n), お・じ・さ・ん (o-ji-sa-n), お・じ・い・さ・ん (o-ji-i-sa-n).

Next, read these words without rushing:

Finally, put them into short sentences:

1. コーヒーをくださいkoohii o kudasaiCoffee, please.
2. ケーキをくださいkeeki o kudasaiCake, please.
3. スーパーにいきますsuupaa ni ikimasuI’m going to the supermarket.

Quick reading and pronunciation check

1. Which means “grandmother / elderly woman”?

• A. おばさん (obasan)
• B. おばあさん (obaasan)

2. Which means “uncle / middle-aged man”?

• A. おじさん (ojisan)
• B. おじいさん (ojiisan)

3. What does ー tell you to do in コーヒー (koohii)?

• A. Pause completely
• B. Lengthen the vowel before it
• C. Make the next sound louder

4. Which word contains a long い (i)?

• A. おじさん (ojisan)
• B. おじいさん (ojiisan)

5. Read this aloud without treating う (u) as a separate strong vowel: こうこう (koukou).

Answers

1. B. おばあさん (obaasan): grandmother / elderly woman.
2. A. おじさん (ojisan): uncle / middle-aged man.
3. B. Lengthen the vowel before it.
4. B. おじいさん (ojiisan): grandfather / elderly man.
5. こうこう (koukou): high school. Give each long お (o) more time rather than saying a separate strong “u” sound.

Frequently asked questions

Do long vowels really change Japanese words?

Yes. Vowel length can distinguish words, as the pair from the start of this lesson shows:

That makes vowel length useful for both speaking and listening.

How long should a long Japanese vowel be?

For beginner practice, think of a long vowel as taking about two beats where a short vowel takes one.

Do not obsess over milliseconds. The practical goal is to make a clear timing difference between pairs such as おばさん (obasan) and おばあさん (obaasan).

Why is a long お sometimes written with う?

Japanese spelling often represents a long お (o) sound with おう (ou), as in こうこう (koukou): high school.

Do not assume that every written う (u) behaves this way. Learn the pronunciation and spelling as part of each word.

What does ー mean in katakana?

The mark ー lengthens the vowel before it, as in these two words:

It is important for pronunciation, so do not skip it when reading.

Continue learning

Practise recognising hiragana and katakana with the YapaneseAI kana learning and practice page.

Build a larger set of familiar words to practise short and long vowels with the YapaneseAI vocabulary lessons.

Continue with more beginner Japanese through the YapaneseAI learning hub.