I've always been curious about the pronunciation of the す in です and at the end of 〜ます verbs. Most commonly the "u" sound is inaudible, but sometimes by some people it's more pronounced, and some people really go for it.

Does it vary by age group, audience, gender, region etc in a way that I haven't picked up on? Can anyone offer any particular guidance for people speaking Japanese as a foreign language?

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    @sawa Thank you for correcting my tags and for the link - I didn't find that in my searches. However I still feel that the focus of my question is different and addresses something that was only touched on there. No hard feelings if people decide to close it though :)
    – ジョン
    Apr 6, 2012 at 22:33
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    I'm in Kyoto and I think people in Kansai tend to pronounce it as 'su' while people in Kanto area pronounce it more like 's'. (My mom is from Tokyo and often says she hates how Kansai-jin pronounce it... she says it's not 美しい日本語.)
    – user1016
    Apr 7, 2012 at 18:14
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    Can anyone offer any particular guidance for people speaking Japanese as a foreign language Use what other people use. Japan has many dialects, and everyone speaks differently.
    – Jesse Good
    Apr 9, 2012 at 6:20
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    I think one instance where it tends to be pronounced is when asking a question using desu/masu tai, but dropping the question particle and using rising intonation at the end. For example: Ikimasu? Apr 11, 2012 at 16:21

4 Answers 4


This is the result of a well known devoicing rule in Japanese. Devoicing means that there is no vibration of the vocal folds. For example, the difference between [s] and [z] is only that [z] is voiced. The IPA diacritic for devoiced phones is a circle at the bottom of the glyph e.g. [z̥]=[s]. Although there is still much dialectal, idiolectal (the way a particular individual uses words), and lexical (the way a particular word is used by individuals) variation in devoicing vowels, and in fact, what is called Japanese vowel devoicing does not in all cases result in merely a devoiced vowel. Taken from The Sounds of Japanese (Vance, 2008):

The so-called devoiced vowel is actually missing entirely in many cases, although traces of it remain as coarticulations in the immediately preceding consonant. Some researchers refer to the affected vowel as reduced, and this term is more accurate as it covers a wider range of possibilities.

A coarticulation in a preceding consonant means that, for a consonant vowel sequence the consonant has been pronounced (articulated) slightly differently in anticipation of the upcoming vowel, so different vowels might result in slightly different articulations of that consonant. Coarticulation is one acoustic feature that complicates speech recognition/synthesis.

The traditional and most simple description of vowel devoicing, taken from An Introduction to Japanese Linguistics (Tsujimura, 2006), gives two conditions for devoicing which Vance calls a good first approximation:

  1. The high vowels /i/ and /u/ are voiceless when they are at the end of the word and are preceded by a voiceless consonant
  2. The high vowels /i/ and /u/ are voiceless between voiceless consonants.

The う in です# and ます# (# represents end of utterance) satisfy the first condition and so undergo devoicing:

  • desɯ# → desɯ̥# since /s/ is a voiceless consonant
  • masɯ# → masɯ̥# since /s/ is a voiceless consonant

If, for example, we have ですか, the う is still devoiced because /ɯ/ is found between /s/ and /k/ (/desɯka/) which are both voiceless consonants and so the 2nd condition is applicable. Devoicing a vowel can be tricky if you deliberately try it in isolation, but to do so just don't let your vocal folds vibrate.

However Vance offers the following relevant observation:

Devoicing between a voiceless consonant and a pause is much less consistent than devoicing between two voiceless consonants.

There is one immediate complication (among several) to devoicing high vowels; what happens when a vowel is both devoiced and pitch-accented, as in the /i/ of 四季 /ɕika/? The contradiction is that you cannot have a high pitch on a phone that isn't voiced (vocal fold vibration, or phonation, is what generates that part of the signal that is perceived as pitch). Usually textbooks (or at least the two that I know of) in a first course of Japanese linguistics will not address this contradiction. This paper Against Marking Accent Locations in Japanese Textbooks (Hasegawa, 1995) argues against this pedagogical simplification:

The fact that native listeners do hear an accent on a devoiced syllable indicates that associating an accent invariably with a high pitch cannot be an accurate description of the language. This paper discusses how Japanese accent is actually realized and argues that marking accent locations in textbooks without a detailed explanation about accent is merely an extra complication that introductory textbooks should avoid.

Devoicing becomes rather complicated when intonation and other exceptional cases are considered, but just looking at the sheer number of papers on the topic it seems to be a well studied and documented feature of Japanese phonology.

  • Besides being more or less prominent in dialects, I'm not really sure what social aspects/trends are associated with this vowel reduction (I like to call it vowel reduction). There's an entire book on the subject of Japanese voicing amazon.ca/Voicing-Japanese-Jeroen-Van-Weijer/dp/3110186004/… that I haven't touched.
    – taylor
    Jul 16, 2012 at 0:10
  • A fantastic answer supplemented by some great extra reading. Well worth the wait. Thank you so much :)
    – ジョン
    Jul 16, 2012 at 7:46

I usually hear people draw out the long "su" at the end of a sentence when giving some sort of presentation or speech (where it gives emphasis to speaker's sentence... or, perhaps, gives the speaker more time to think about what to say next.) It happens in English, too, like when a voice-over announcer makes something sound more dramatic.

In most general conversation, keeping the short "s" sound should be fine.


I've long been puzzled by this. I've been told it was more common in Kansai, but I've definitely heard it in Tokyo, although I have no idea where the people were originally from. People have told me it was a dialectal difference, only to get caught saying it themselves later. Go figure.

It's particularly common in short expressive phrases like そう(なん)です~. I can only suppose the extra vowel allows for more expression. I sometimes feel it almost replaces ね.

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    +1 for confirming my sanity. I too have a feeling I've heard it more from Osaka/Kyoto friends, but I've heard it from people native to Tokyo too. I get the feeling it's a Kansai stereotype, but in reality much more widespread. Don't know if that's accurate.
    – ジョン
    Apr 17, 2012 at 15:06
  • @alexandrec Did you mean to say "it almost replaces よ" instead of "it almost replaces ね"?
    – Pacerier
    Apr 19, 2012 at 23:34

The best way I can describe the normal sound of the 'u' part of す is that it is said as far under your breath as possible. However there is always a sound even if it is not noticeable. It takes a fair bit of exposure to pick it up.

One of the problems you are probably having with this is that your text book says that you just drop the 'u' part at the end. This really isn't true at all, the correct sound is just hard for English speakers to say at first.

ます does not sound like 'mas' as in the English 'Christmas', there is always something after the 's' part.

That being said if your untrained ears hear a 'u' that sound like as in the English 'sue', there are two possible reasons for that.

1) The person is making fun of your accent (as English speakers tend to really mess this up).

2) They are asking a question. Asking a question in this way is normally considered less polite than adding か.

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    I was lucky enough to live in Tokyo for two years and study at a school where I was one of only two fluent English speakers in the class. As such my education wasn't geared towards English speakers at all, and I managed to avoid a lot of those bad habits. So while my pronunciation isn't perfect by any means, standard です・ます pronunciation is second nature by now. What I'm asking about here is this non-standard pronunciation, which I would hear all around Tokyo and on TV, not just my own conversations. Your answer will be helpful to someone I'm sure, but not the one I'm looking for I'm afraid :(
    – ジョン
    Apr 17, 2012 at 14:53
  • The point I am trying to make here is that I have never heard it pronounced differently based on region or other personal factors. を however is pronounced differently between different people. What you are referring to is not the pronunciation anyways, it is the tone. It is a falling tone normally, so you hearing it or not hearing it depends on the volume of the speakers voice more than anything. Remember just because something isn't noticeably audible doesn't mean it wasn't pronounced.
    – Ian
    Apr 19, 2012 at 0:16
  • I'm sorry, but I and others have heard it pronounced differently, and my question is not about the pronunciation of を. I don't know if it's based on region/personal factors - that's part of my question. Your answer seems to assume that if I've heard variations like this then my "untrained ears" and/or my own accent must be to blame. Making such assumptions about people asking questions here is not conducive to a helpful learning experience. Once again, I understand that the "u" in す is not dropped completely. I'm asking why it sometimes (and by some people) seems more pronounced.
    – ジョン
    Apr 19, 2012 at 0:31
  • Finally, I don't see the problem with the word pronunciation here. I really am grateful for your answer, but it's not what I was looking for. I'd prefer to hear from someone who has heard the difference I'm referring to and is in a position to try and explain it. These comments are getting lengthy (my own fault), so I'll leave it at this unless you'd like to branch this discussion into chat.
    – ジョン
    Apr 19, 2012 at 0:33
  • @ジョン I was talking to a person from Kansai today and noticed them use a very extended る sound, it was like るうぅぅ. This adds something to the argument that people from Kansai do this. The sentence it was used in was a question of sorts. However I notice no extra ぅ sounds on any of her other sentences. Personally I think this adds credibly to what I said above. However it also adds credibly to comments that say it is regional. If this sound is regional, it is not something that is used outside of a limited set of contexts. However I am not sure what those contexts are.
    – Ian
    Apr 29, 2012 at 1:30

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