I found that there are two different pronunciations for the [ɸ] phone. For example, in Japanese compare those two pronunciations for same word 冬 (for which I believe will has [ɸɯjɯ] as phonetic transcription):

In this wikipedia page, which provides the audio sample for the sound (near the top right of the page), I also found that phone is pronounced much similar to the first link in the list above.

However, some other sources suggest that the pronunciation link in second link is also common. For example, this link: http://www.guidetojapanese.org/learn/grammar/hiragana provides pronunciation for /hu/.

So which one is correct, or both?

Note: I'm a Vietnamese native speaker and in our country, almost anyone can spot the difference between the two pronunciations in the links listed above.

  • 4
    Does this answer your question? Why doesn't Japanese have a special Katakana form for "hu"? [f] simply does not exist in Japanese; the upper teeth never touch the lower lip. [ɸ] exists as one of the allophones of the /h/ consonant.
    – naruto
    Jun 15, 2020 at 5:17
  • I've also read one page that is similar to the link you ref. However, it's not answering to what I'm asking here. My question is that what is the correct pronunciation of 冬 cause my ear hears different sounds, or both can be correct depends on accent?
    – Khanh Tran
    Jun 16, 2020 at 1:24
  • Please check the first link, I can see no audio button. And my ear is not good enough to distinguish [f] and [Φ] precisely, so I may not be able to tell the difference.
    – naruto
    Jun 16, 2020 at 2:04
  • @petwho Well... the first two are speech synth and the last one is a "theoretical" example that may not resemble actual sound in a specific language. Though I agree that those clips sound "different", but they are too "different" to identify what you call "correct" (unless you give me a phonetic description). I think you should try look up some real human examples from forvo.com and see if you hear any weirdness. Jun 16, 2020 at 7:05
  • @naruto It's near the top right, I believe if you search for "Audio sample" you'll find it.
    – Khanh Tran
    Jun 16, 2020 at 10:04

2 Answers 2


It turns out that OP's question is that Japanese ふ sometimes sounds as if Vietnamese ph //f// and other times kh //x//.

That observation is true. The status of [[ɸ]] sound in Japanese is somewhat shaky because it appears mostly as an allophone in the environment //h// + //u// (strictly speaking, however, influx of modern loanwords has developed independent ファ行 to a quite degree).

[[ɸ]] in the Japanese language is a historical remnant of the times when all ハ行 were //ɸ//, which now only retained because //u// has labial feature. Hence, to some speakers the labiality is essential in pronunciation, while to others it is merely incidentally labialized //h//. In other words, the strength of labial narrowing varies among speakers.

Another factor is the realization of //h//. It is pronounced not only as [[h]] but also as [[x]] or [[χ]], especially in Eastern Japan including Tokyo. (Note that these allophones are natural in most regions when after consonantal element, cf. ゴッホ.) Since we don't have any contrastive fricatives in the back side of cavity, //h// can be freely realized from [[h]] (≈ Vietnamese h) to [[x]] (≈ Vietnamese kh).

Then we can draw a diagram to illustrate the gradation of ふ's consonant:

strong labial                      [ɸ]
 weak labial           [hʷ]                    [xʷ]
                      glottal <--------------> velar

For example, in the sound clips of 船(ふね) on forvo.com, strawberrybrown's is closest to [[ɸ]], akitomo's closest to [[hʷ]], and kaoring's closest to [[xʷ]] (I couldn't get each direct link).

I'm not sure what is the distinctive features of ph in Vietnamese, but your first link of 冬 from jisho.org sounds rather an example of [[hʷ]] (though it doesn't seem to be a human articulation).

PS As an aside, it reminds me of a female announcement voice for some JR lines which utters ふつう with such strikingly dominant velar feature that almost sounds like くつう to me.

  • While your answer is pretty informative (thanks a lot for your help), I also found my own answer. Please read my answer below and comments are absolutely welcome.
    – Khanh Tran
    Jun 19, 2020 at 4:27
  • 1
    @petwho So... it seems to me that what you wanted as an answer is the thing you wrote in the title (about [[ɸ]]), but what I answered is what you wrote in the question body (about //hu//'s allophones in Japanese). I sense a slight confusion on this matter, for example when you say "[x]... my preference is to use [kʰ]". I'm sure what you indicate here is //x// and //kʰ//. Because / / notes items in speaker's mind, and [ ] notes real sounds (See here). Jun 19, 2020 at 6:11
  • From what I collected, some Vietnamese speakers do pronounce kh in Quoc Ngu as [[x]] while others [[kʰ]], and such difference means little in Vietnamese, right? In this case, what you talking about should be written something like //kh// (the letters between slashes don't need to be real IPA sign, //あ// is also okay if you want). If I guessed right, you asked how to pronounce [[ɸ]] because you believe Japanese //ふ//'s consonant should always be it but actual audio didn't sound that, and I answered that Japanese //ふ// is not always pronounced with [[ɸ]]. Jun 19, 2020 at 6:20

I found answer for it after days of searching on the internet.

Important note: The actual sound may vary depending on the accent of the speaker as you can find in the links that I posted in the questions.

Some people pronounce [ɸ] as in ふ the following way:

  • Try to make a voiceless sound as if you are blowing a balloon (the [ɸ] appears here).
  • Add ɯ sound (for ふ in this case)

The Youtube video links for the above pronunciation can be found here and here also.

Some other people pronounce the [ɸ] sound the same with [x] (or my preference is to use [kʰ] in this case instead), ref: https://en.wikipedia.org/wiki/Voiceless_velar_fricative.

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